Coop ventilation: Here’s exactly how much your chickens need
How much ventilation does a chicken coop need?
Ah, the million-dollar question!
Here’s the answer:
Chicken coops need much less ventilation during the cold months than during the warm months. A chicken coop needs about 3-4 square feet of ventilation (including the pop door) in cold weather, and as much additional ventilation as possible in hot weather, typically in the form of windows, vents, and doors that can be opened when needed.
Figuring out how much ventilation you really need can be tough for newbie chicken keepers. There’s no hard and fast rule (despite what you might read elsewhere)—it truly can vary.
Most ventilation estimates you find give a number so high there’s no possible way you could ventilate that much without creating dangerous winter drafts in your coop.
So, in this article, we’re going to figure out exactly how much ventilation is right for you. We’ll quickly cover the 12 simple variables you need to consider, and then I’ll give you some examples from my own chicken coops (with photos!).
This way, you’ll be able to actually visualize what your coop ventilation should look like, where to put it, and exactly how much ventilation you’ll need for your setup.
This post contains affiliate links for my favorite products from Amazon. As an associate, I earn from qualifying purchases at no extra cost to you.
Why do you need ventilation in your coop?
If you’re not quite sure what ventilation is or why you need it, check out my companion article, Chicken coop ventilation 101: Ventilation made easy!
12 variables to determine how much ventilation your chicken coop needs
The table below summarizes the 12 variables you need to consider to determine how much ventilation your chicken coop needs. The variables are listed in the left-hand column.
Take a minute to look at these variables, and see if your backyard setup falls more in the middle column or the right-hand column.
| Ventilation variable | More ventilation needed | Less ventilation needed |
|---|---|---|
| Bedding/litter type | Organic (i.e., not sand) | Sand |
| Frequency you change or clean bedding | Less frequent (>1-2 weeks) | More frequent (≤1-2 weeks) |
| Use of droppings boards | No | Yes |
| Temperature | Hot weather | Cool/cold weather |
| Nighttime summer temperatures | Stay high | Cool down |
| Coop location (if you get high Ts) | Sun | Shade |
| Humidity | High | Low |
| # chickens/sq ft | Crowded (<4 sq ft/chicken) | Not crowded (4+ sq ft/chicken) |
| Height of ceiling | Low | High |
| Time chickens spend in the coop | Lots | Normally outside during the day |
| Chicken sizes | Large | Average or small |
| Chicken breeds (if you get high Ts) | Heat-intolerant | Heat-tolerant |
Let’s take a closer look at the 12 variables and what they mean for you.
#1 Coops with organic bedding need more ventilation than coops with inorganic bedding.
What type of bedding will you be using in your coop?
If you’re using anything organic—straw, wood shavings, hemp, paper, etc.—you’re going to have a lot more moisture and gas in your coop than if you use inorganic bedding—i.e., sand.
Organic beddings don’t dry out moisture as well as sand, and they also provide a lot of organic matter for pathogens to break down (creating gases). This combination means you’ll have more moisture, gas, odors, and pathogens in your coop’s air, and therefore, you’ll need more ventilation.
If, on the other hand, you use a medium- to coarse-grained sand bedding (my bedding of choice), you won’t need as much ventilation in your coop. Sand dries chicken poop up quickly and doesn’t support pathogenic growth.
For the science behind this (including references), check out my article, The BEST chicken coop bedding: Sand vs. straw vs. pine shavings.
For advice on what kind of sand to get, where to get it, and how to use it, see my article, Sand for chicken coop bedding: Pros, cons, and how to do it right.
And for information on the myth that all sands will make your chickens sick, see my article, Will all sand bedding kill your chickens? Silica and silicosis explained.
#2 The more frequently you change your litter or remove the droppings, the less ventilation you need.
The majority of your coop’s moisture, gases, and pathogens are coming from your chickens’ poopy bedding. So, obviously, if you’re replacing organic bedding frequently, or you’re removing the droppings from your bedding frequently, your ventilation needs will decrease.
This is another reason sand is a wonderful bedding type—it’s so easy to clean. You just scoop the poop right out. For more on this topic, see my article, Sand for chicken coop bedding: Pros, cons, and how to do it right.
And if you’re using an organic bedding type, you may want to consider sprinkling some zeolite into it—this will help discourage pathogen growth and reduce the gases.
#3 If you use droppings boards under your roosts, you won’t need as much ventilation.
Droppings boards (or trays) are any material (typically plywood) you put underneath your roosting bars to catch your chickens’ nighttime droppings.
You can see what one of my droppings boards looks like in the photo below.
If you use droppings boards, you can easily use a taping knife to scrape the poop off each day into a bucket, and remove it from the coop.
If you use trays, you can fill them with some kind of litter and just scoop the poop out. Many chicken keepers use trays of sand or zeolite litter, and then they just use a kitty litter scooper to remove the droppings each morning.
This practice removes the majority of chicken poop from your coops, thereby removing a significant amount of moisture, bacteria food, and gases (which are typically released by bacteria during the breakdown of poop and bedding).
#4 Coops in hot climates need more ventilation than coops in cold climates.
In hot weather, ventilation plays the added role of cooling down the coop. The more ventilation you have in your coop, the more airflow you have, and the cooler your coop is.
If your climate is hot year-round, consider an open-wall coop. This is a coop where one or more walls (or parts of walls) are made from hardware cloth, so your coop has a very large amount of ventilation. You can see a couple examples in the photos below:
And if you get the occasional storm or bad-weather spell, design your coop so you can cover the open walls with plywood boards or with a heavy-duty tarp as needed. However, make sure when you cover the walls you do still leave open space at the top to ventilate moisture and gas.
I also recommend using fans in the coop in hot climates. For more info on using fans for ventilation, see my article, Chicken coop ventilation 101: Ventilation made easy!
#5 If your nighttime temperatures remain high in the summer, your chickens will need more ventilation.
And fans… Definitely consider fans here...
Going 24 hours per day, 7 days a week without ever cooling off is incredibly hard on your chickens. In fact, it’s a recipe for heatstroke. If the weather never cools down, make sure your coop has as much ventilation as possible, and add some fans to help your girls cool off.
For more ideas on how to add ventilation, see my article, Chicken coop ventilation: 21 design ideas with pictures.
#6 Coops located in the sun will need more ventilation during hot weather.
As a chicken keeper living in southern Idaho, where trees are hard to find, my coops have absolutely no cover. This means the hot sun beats down on them all day during the summertime. Insulation goes a long way in helping to keep my coops from bursting into flames, but my coops still get hotter than shaded coops do.
If you are unable to put your chicken coop in the shade and you get summer where you live, you’ll need to ventilate well in the summer to keep your coop cool enough. The more airflow you can get, the better.
#7 Coops in places with high humidity need more ventilation.
Again, one of the main reasons that coops need ventilation is to remove moisture. In humid places, fresh airflow is even more important. Humidity makes it harder for chickens to cool down in the heat, and humidity increases your chickens’ risk for frostbite in the cold.
#8 The more chickens you have per square foot of space, the more ventilation you need.
The more chickens you pack in a small space, the more concentrated the moisture they produce.
Not sure how much space you need for your chickens? See my article, How big should your chicken coop be?
#9 The higher your ceiling, the less ventilation you need.
You’ll often see ventilation estimates based on square footage in the coop—for example, you might have come across the recommendation of “1 square foot of ventilation per every 10 square feet of floor space.” However, these recommendations always fail to take into account the height of the coop (and pretty much every other variable listed here)
If your coop has a higher ceiling, like a typical walk-in coop, the moisture and unwanted gases in the air will be less concentrated and will tend to rise into the ceiling above your chickens’ heads. (And it’s a great idea to have a vent in or near your ceiling for this reason.)
On the other hand, if your coop has a low ceiling (not very far above your chickens’ heads), the stale air will be more concentrated and much nearer to your chickens—you absolutely will need a vent large enough for this air to exit through immediately, either in or near the ceiling.
There are several different kinds of vents you can add—for ideas, see my article, Chicken coop ventilation: 21 design ideas with pictures.
And if your ceiling is low, definitely consider hanging a Sweeter Heater above the roosting bars in the cold months. This will help protect your chickens from cold drafts that may be coming from the vents not far above their heads. It’ll also protect them from frostbite, which is sadly common in backyard chickens.
The photo below shows the interior of my smallest coop on a cold day. You can see a couple of my chickens, Dolly and Champ, under their Sweeter Heater.
Later in this post, I break down exactly how much ventilation the coop pictured above has.
#10 The more time your chickens spend in the coop, the more ventilation they’ll need.
If you have a small run or a run that’s not protected from the elements, your chickens may spend a lot more time in the chicken coop.
And what are they doing in there? Pooping and breathing all over the place, of course—hence, the need for greater ventilation.
#11 Larger breeds need more ventilation than smaller breeds.
Of course, larger breeds eat, poop, and breath more, and therefore will have greater ventilation requirements in the same amount of space.
#12 Heat-intolerant breeds need more ventilation than heat-tolerant breeds.
Your heat-intolerant breeds, such as Wyandottes and Orpingtons, will need all the help they can get during the summer months. They need lots of airflow—again, think fans.
How to use these 12 variables to determine how much ventilation your chickens need.
Most of these variables are FYI—basically, if you’re getting a lot of variables in the middle column, you’re going to make sure you go heavier on ventilation, whereas if you’re getting a lot of variables in the right column, you can go lighter.
The absolute most important variables are the ones dealing with heat. If you live in a hot climate—ventilate, ventilate, ventilate.
What if you live in a climate with hot summers and cold winters?
Most people live in climates that get both hot and cold, myself included. This means your coop will have different summer ventilation requirements than it will in the winter.
Summer drafts are good. Winter drafts are bad.
For summer, you’ll want as many vents and windows open as you can—and even doors, if you have a way to do that safely. In many places, you’ll need to add fans too.
And then, in the winter, you’ll need to close your windows and extra vents. You’ll need to make sure the only ventilation you have in your coop is vents that are located well above your chickens’ heads and the pop door.
Basically, you’ll need to model your coop for adjustable ventilation. For more on this topic, see my article, Chicken coop ventilation 101: Ventilation made easy!
Chicken coop ventilation: Let’s talk numbers!
I went out this morning and measured all the ventilation in my biggest and my smallest coops and got some photos—so you can get real numbers and see what those numbers actually look like on a coop.
Ventilation for a 10’x10’ walk-in chicken coop with 25 chickens
Below, you can see a photo of my 10’x10’ walk-in chicken coop.
This coop has two gable vents on opposite walls with an area of 4.69 square feet each—you can see one in the photo above.
The coop has two windows with a vent area of 1.69 square feet each—you can see one in the photo above—and a pop door that’s 1.25 square feet. The human door, were I able to leave it open, is 19.11 square feet.
You can see these numbers summarized in the table below.
| Coop size | # of chickens | Vents | Windows | Pop door | Human door |
|---|---|---|---|---|---|
|
Large (10'x10' walk-in)
|
25 | 2 at 4.69 sq ft each | 2 at 1.69 sq ft each | 1.25 sq ft | 19.11 sq ft |
Winter ventilation for the 10’x10’ coop
How much ventilation does this end up being? Well, in the winter, I close the windows and I close one of the gable vents. Yes, the second gable vent is totally unneeded in the winter months. In fact, the coop feels a bit drafty with it open, despite the fact it’s well above the chickens’ heads.
So, my winter ventilation ends up being 5.94 square feet total—the size of the pop hole door plus the size of one gable vent.
That’s only 0.24 square feet/chicken.
And, honestly, I think the coop would be fine with less. There’s plenty of airflow. The coop is dry, and there are absolutely no odors—aside from first thing in the morning when there’s a whole night’s worth of fresh poop on the droppings boards from 25 chickens. But as soon as I scrape that off, the coop is fresh.
I think had I just installed two 1-square-foot louvre vents on opposite walls, that would have been enough—and that works out to just 0.13 square feet/chicken.
So, when you see the ventilation estimate everywhere that you need at least 1 square foot of ventilation per chicken (and that doesn’t even include the pop door!), it’s totally bogus—or, at least it is during the winter in a coop with good management.
And by good management, I mean your coop has no less than ~3-4 square feet/chicken and you remove poop frequently—either by scooping it out of the sand or by replacing your organic bedding.
And what about the estimate of 1 square foot of ventilation for every 10 square feet of floor space? Also bogus. In the case of this coop, I have only 0.59 square ft of ventilation for every 10 square feet of floor space.
Summer ventilation for the 10’x10’ coop
And what about in the summer? Well, for summer ventilation, I open both gable vents, both windows, and the pop door. This amounts to 14 square feet of total ventilation or 0.56 square feet/chicken.
However, I do wish I had more ventilation in the summer months, just because the coop does get warmer than I like, sitting out in the sun like that. So, I do add a DeWalt battery-powered fan to the coop in the summer.
Additionally, the nights do cool down quite a bit here. If they didn’t, I’d add even more fans.
And if I needed to, I could leave the human door open for this large coop if I added a securely latched screen door covered with hardware cloth to keep predators out at night. This would add another 19.11 square feet of ventilation, for a total of 1.3 square feet per chicken.
Ventilation for a 4’x4’ elevated coop with 4 chickens
Below, you can see a photo of my 4’x4’ elevated chicken coop.
This coop has two vents right below the roof (on opposite sides of the coop). I call these wall-roof gap vents. They’re simply gaps between the ceiling and top of the wall, and they’re covered with hardware cloth. You can see one in the photo above—it starts at the top of the door, although you can’t see the hardware cloth from this angle.
But you can see the hardware cloth in the closeup photos of the vent below.
These vents each have an area of 1.39 square feet. The coop has one window with a vent area of 0.92 square feet, and a pop hole that’s 0.73 square feet. The human door, were I able to leave it open, is 9.44 square feet.
You can see these numbers summarized in the table below.
| Coop size | # of chickens | Vents | Windows | Pop door | Human door |
|---|---|---|---|---|---|
|
Small (4'x4')
|
4 | 2 at 1.49 sq ft each | 1 at 0.92 sq ft | 0.73 sq ft | 9.44 sq ft |
Winter ventilation for the 4’x4’ coop
In the winter, this chicken coop is ventilated by the two wall-roof vents and the pop door, a total of 3.71 square feet of ventilation.
That’s about 0.93 square feet per chicken.
This is definitely enough—I’ve never had any problems with moisture or gases in this coop. You might be thinking, well, that’s pretty close to the 1 square foot per chicken estimate. But remember, that estimate doesn’t count the pop door. I do count the pop door as ventilation.
Summer ventilation for the 4’x4’ coop
In the summer, I also keep the window open, so the coop has a total ventilation area of 4.63 square feet. That’s 1.16 square feet per chicken.
Again, this has proven to be more than enough. (Although, I wouldn’t complain if there were even more—you really can’t have too much ventilation in the heat.)
Although my husband built this coop to house 4 chickens, one summer I ended up with 7 chickens in it—6 hens and a rooster. The chickens were originally living in two coops this size, but then chose to all pack into one coop together—much to my annoyance. (Yes, they have a brand-new large coop now.)
But that summer with 7 chickens in that coop, the ventilation amounted to only 0.63 square feet per chicken, including the pop door. And still, it was enough!
You can see the ventilation numbers I’ve discussed here summarized below—for both the large and small coops:
| Coop size | # of chickens | Winter ventilation | Summer ventilation |
|---|---|---|---|
|
Large (10'x10' walk-in)
|
25 |
5.94 sq ft total* 0.24 sq ft/chicken 0.59 sq ft/10 sq ft floor |
14 sq ft total 0.56 sq ft/chicken 1.40 sq ft/10 sq ft floor |
|
Small (4'x4')
|
4 |
3.71 sq ft total 0.93 sq ft/chicken 2.32 sq ft/10 sq ft floor |
4.63 sq ft total 1.11 sq ft/chicken 2.89 sq ft/10 sq ft floor |
*Although this coop has 5,94 sq ft of ventilation total, this coop feels overventilated—it’s very cold with a lot of airflow. If I were able to go back in time, I would install gable vents that were 1 sq ft each instead of 4.69 sq ft each, which would reduce the total winter ventilation to 3.25 sq. ft.
You can see in the table above that I’ve broken the ventilation down into square footage/chicken and also into square footage per 10 square feet of floor space.
I’ve done this because you always hear you need “1 square foot of ventilation per chicken” or “1 square foot of ventilation per 10 square feet of floor space.” This table shows how inaccurate and unhelpful these rules of thumb truly are.
And again, remember I could greatly increase the ventilation in the summer if I needed to by leaving the human doors open (and adding hardware cloth to keep predators out). So, keep that in mind for your coop. And, of course, there’re always fans.
Do pop doors count as ventilation?
Yes, absolutely. I’m sure you’ve noticed I counted pop doors in all my measurements above.
As long as your pop doors aren’t covered with curtains, pop doors play a major role in bringing fresh air into your coop. Even though you typically close them at night, they still bring in massive amounts of air all day long.
What does this all mean for you? Let’s put it together.
Here’s what this all means for you. Chicken coop ventilation doesn’t have to be complicated. If you live in a hot climate, ventilate as much as you can and use fans.
Don’t shoot for a certain square footage of ventilation per chicken or per floor space. Just ventilate as much as you can, while still making sure your chickens are protected from the elements and predators.
If you live in a cold climate, make sure you only have ventilation high above your chickens’ heads (plus the pop door—which you may choose to leave open or cover with curtains).
And always shoot for some cross-ventilation too. For example, if you leave your pop door uncovered during the day, fresh air will come in through that and stale air will go out the vent near the roof. That’s cross-ventilation.
Or, in the case of my small coop pictured above. The wall-roof gap on the low side of the roof cross-ventilates with the wall-roof gap on the high (opposite) side of the roof. Air flows in the coop from one side and out the other, taking the coop’s gases and moisture out with it.
Basically, just make sure you have vents that differ in location vertically (like a pop door near the floor and a vent near the ceiling) or laterally (like two vents on opposite sides of your coop). Either of these setups will ensure you’re getting cross-ventilation.
And then, of course, if you live in a mixed climate—both cold and hot weather—just make sure you have plenty of adjustable ventilation, such as vents and windows that you can open and close as the weather dictates.
You can see this advice summarized in the table below:
| Hot climate | Cold climate | Mixed climate | |
|---|---|---|---|
|
Ventilation requirements
|
Ventilate as much as you can, while still protecting against the elements and predators Use fans if necessary |
Use cross-ventilation with vents that are high above chicken head-level and pop doors 3-4 square feet total ventilation is typically enough |
Use Adjustable ventilation Cold climate ventilation PLUS additional windows, vents, or doors you can open in the hot months Use fans if necessary |
And lastly, run a clean coop. Get that poop out of there. Without a bunch of poop in your coop, there’s only so much moisture and gas leftover you even need to ventilate.
And if, for some reason, you know you won’t be running a clean coop, you’re going to need more ventilation. But ask yourself, why aren’t you running a clean coop?
How do you know for sure if your chicken coop has enough ventilation?
Easy—you test it.
Ask yourself these 3 questions:
Is there condensation in your coop?
Does your coop have moist spots anywhere?
Does your coop stink?
If you answered no to all 3 of these questions, congratulations! Your coop is well-ventilated!
If you answered yes to the first question, it may mean you don’t have enough ventilation, but if the condensation is on the roof, it may also mean you just need to insulate your roof.
And if you see moist spots, first make sure you have no leaks and that precipitation isn’t coming in through your vents. These aren’t ventilation problems—these are construction problems. And if you need ideas on how to prevent precipitation from coming into your vents, see my article, Chicken coop ventilation 101: Ventilation made easy!
And don’t forget your coop might stink like chicken poop first thing in the morning before you’ve had a chance to clean your droppings boards (or scoop the poop out of your bedding, if you don’t have droppings boards). This is totally normal—ventilation or not, fresh poop stinks.
However, if your coop continues to smell bad, or it smells anything at all like ammonia—or any other gases, for that matter—you either don’t have enough ventilation or you need to replace your bedding immediately. Sometimes both.
What should you do if your coop doesn’t have enough ventilation?
Add some more!
Not sure how? Check out my other articles on ventilation for ideas and tips: