How Big Should a Garage Bathroom Be?

A garage doesn’t just have to be space for parking vehicles. For many people, especially those that have a detached garage, it’s also a workshop, a storeroom, and even a recreation area. 

In some cases, adding a bathroom to the garage just makes a lot of sense. However, we have to take into consideration the costs and effort involved. The size of the garage bathroom is also a considerable factor, so let’s take a look at how to figure out the right calculations: 

1. The Size of the Garage

The Size of the Garage

Constructing a garage bathroom will involve a lot of challenges. There are structural issues, along with plumbing and electric elements to consider. While it will make working in the garage more comfortable and convenient, this bathroom might take quite a bit of time and hassle. 

If the size of your garage is large, you will obviously have more room for a larger bathroom. This will also be a bit more convenient for you, as there are more chances of you continuing to work in the garage while the bathroom construction is going on. While a large garage can work well with a small bathroom, a small garage shouldn’t be fitted with a large bathroom. The latter combination simply makes no sense; the bathroom will just take up the already limited space. Unless the garage occupant is a social media influencer who takes a lot of pictures in the bathroom, this room should be kept as small as possible. 

In general, though, the smallest you can probably go for any kind of bathroom is 15 square feet. This area will just hold a sink and toilet bowl according to most regulations. If there’s a shower, the size of the bathroom will have to be around 30 to 36 square feet. For those wanting a full bath, the cost will go way up with around 40 square feet dedicated to the bathroom. Keep these factors in mind when you’re determined how to add a bathroom to a garage. 

Every bathroom also needs a ventilation system, so make sure your garage is large enough to accommodate that. At the very least, you’d need a window measuring about 1.5 square feet and above. 

2. The Budget

The Budget

We may like the idea of a large, spacious bathroom in our garage, but the hard fact is that such an addition will be expensive. Even getting the bare minimum size of a garage bathroom can put you back several thousand dollars. 

It’s not just the material and labor that make up this cost. It’s also the changes you will have to make in the walls, the plumbing, the electricity, etc. Add this to the cost of fees, permits, and perhaps insurances; you just might be looking at a bill of over $25,000 in total. 

A garage bathroom’s benefits might outweigh the costs, though. You might be getting a much-needed second bathroom for your household, or have a livable space for paying guests. If it’s the latter, the earnings from the bathroom might cover the costs in about a year. 

3. How You Use the Garage and How Much

How You Use the Garage and How Much

A garage is a versatile space; some people may not even use it for their cars. Many families and individuals find this space perfect for storing unused sports equipment that they use only when the season is right. Some have made even more use of it, converting a part of the garage space to their personal workshop, private entertainment corner, a hangout place for their friends, or a safe place for the kids to play if they can’t go outside. 

Overall, a garage is a space that’s somewhat separate from the rest of the home. Even if it’s directly connected to the house, that large, mostly furniture-free space is a very tempting spot. Depending on how much you use the garage and for what purpose, you can determine the required size of its bathroom. 

If someone is spending most of their day in the garage–they might be working on a carpentry project or going there to create some artwork–having a bathroom there can allow them to work without breaking the flow of creativity too much. If it’s just that, though, you can probably do with a small bathroom that just holds a toilet bowl and a sink. Taking a shower is usually not necessary in such cases. 

At times, you may have a guest or family member living in the garage on a temporary or permanent basis. In that case, a garage bathroom becomes a necessity. The next point will touch on these ideas in some more detail. 

4. Intended Future Use

Intended Future Use

When someone adds a bathroom to their garage, the main aim is to utilize the garage even more than usual. At times, your intention may not be to make working in the garage more convenient, but to gain an additional benefit from that area. While there are several reasons to install a garage on the bathroom, it’s important to consider your intention for the future as well.  

For instance, one of the family members in a house may want to move out and start their own semi-independent living when they get a bit older. With the high rent rates and other concerns, many parents allow their grown-up offspring to move into the garage or any other space. This way, the young adult gets a taste of freedom and independence while not being too far away from their family. 

Some people may also want to turn their garage into a guest room when needed. They might have a regular guest coming in from out of town, or frequently have people over to stay the night. The intention may also be to have a cozy space to put on AirBnB and earn some extra cash. 

In such cases, the size of the garage bathroom will depend on the needs of a person. Instead of a household member spending most of the day in the garage and just needing a toilet and sink, you now need to install a shower or bath as well. 

While a shower won’t take up much space, a paying guest might be more attracted by the prospect of a bath, a vanity with the sink, or just a little more space than absolutely necessary. With this in mind, it will probably be a good idea to make the garage bathroom a little bigger than the standard 15 feet square or even the 35 square feet required for adding on just a shower. 

5. The Laws of the Area

The Laws of the Area

No matter where you’re located, it’s not legal to install a bathroom wherever and whenever you like. Before looking at these tips for adding a bathroom to your garage, make sure to look up the limits and laws for such additions. 

Technically speaking, most areas will allow you to add a bathroom to your garage. If you own the place, you can probably add in whatever you like within the legal limits. If you’re renting long term, make sure to consult your landlord. However, the rules and regulations for standalone garages and attached garages might vary according to where you live. In all events, keep things legal and above board to prevent any legal hassle later on. 

Always check the building permit codes before embarking on a major project like a garage bathroom. You may need to get special building code permits, especially if the garage is detached from the main house. The local building authorities should be able to guide you best, so do check in with them before even getting an estimate on the renovation or construction. 

The bathroom needs to be planned in accordance with the regulations along with the needs of the local community. After all, a bathroom can cause seepage issues, which can cause damage to your neighbor’s homes as well as your own. This is why it’s important to check the requirements for space clearance and renovation before deciding on the kind of plumbing and layout your bathroom will have. 

According to the International Residential Code for such requirements, one would need to keep around 21 inches clearance at the front of the toilet bowl and around 15 inches on both sides before installing the toilet. 

For a shower entrance, you’ll need 24 inches clearance at its front. The area for showering needs to be around 30 by 30 inches. 


A garage bathroom can be a very useful addition to your home. As long as it’s all legal and within limits, this room can also add a lot of value to the limit. While the monetary investment can be quite heavy, it can be recovered if you choose to earn from that space. Since the garage is versatile, you can always think about renting it in the near future and utilizing it yourself for now. Start thinking about installing a garage bathroom today and see if it’s viable.