Measure twice, buy one toilet
Toilets last up to 50 years, but there comes a time when all bathroom fixtures require replacement. Toilets are not “one-size-fits-all,” so to make sure you don’t end up with a mismatched unit, take the toilet rough-in measurement before buying a new one. Taking this measurement will ensure your new toilet lines up with the preexisting drainpipe. Many companies don’t allow toilets to be returned, so follow this article to get your toilet rough-in dimensions right the first time.
Before breaking out the toolbox, let’s go over the exact definition of a toilet rough-in measurement. Simply put, this is the distance from the wall to the drainpipe, otherwise called the toilet flange or water outlet. The rough-in measurement starts from the wall at the back of the toilet and extends to the center of the drainpipe that sits directly beneath the toilet bowl.
Why is the rough-in so important? There are many toilet designs out there, and if the measurements are off, your newly purchased model will not fit over the drainpipe—making it a useless slab of porcelain. Moving this rough-in location costs an average of $7,000, so it’s much easier and more budget-friendly to purchase a toilet for the existing rough-in distance. You can call in a toilet installation pro to measure this for you to be safe.
While not one-size-fits-all, there are a few rough-in measurements that account for the vast majority of bathroom setups. The standard is a 12-inch rough-in, though 10-inch and 14-inch rough-ins are also relatively common. Of course, some wild card setups change this up even further. In other words, conducting a successful rough-in measurement, no matter the result, is paramount before buying a new toilet and removing your old toilet. Here is how to do just that.
Unless you’re building a home from scratch, you likely already have a toilet in the bathroom. Luckily, you don’t have to remove the toilet to get accurate rough-in toilet dimensions.
Start by identifying the base bolts. Look for small bolts, or caps, at the base of the toilet. These are normally located on the back left and right side of the fixture, though the location may vary on skirted toilets. Look for any sign of bolts at either side where the toilet meets the floor. Put a piece of painter’s tape on each bolt to make them easier to identify as you measure.
Use a common tape measure and go from the bare wall behind the toilet to the center of the toilet’s base bolts. This is the rough-in distance. For accurate measurements, avoid moldings and baseboards as you measure. Adjust the tape so it starts from the bare wall.
Double- and triple-check your work, particularly if you came back with a measurement other than 10, 12, or 14 inches.
The process is slightly simpler when measuring a bare bathroom floor for a toilet rough-in distance, as there are no bolts to deal with (or a toilet).
Find the drainpipe, also called the toilet flange opening, on the floor. It’s easy to spot—look for the round hole cut out of the floor with a white plastic lining.
Measure from the bare wall behind where the toilet will rest to the direct center of this opening. This is your rough-in distance. For accuracy in the case of baseboards and moldings, raise the measuring tape, so it touches the bare wall.
One measurement is never enough here. Better safe than sorry, right? Repeat this process several times, particularly if you get a measurement outside the norm. Remember, measure to the center of the drainpipe and not any distance along the perimeter of the hole.
It’s slightly more complicated to get an accurate rough-in measurement for a corner toilet, but it’s still doable.
Find where the toilet is bolted to the floor. Look for the telltale bolt caps on both sides of the fixture (toward the rear).
The existing toilet covers up the drainpipe, so use the bolts to estimate its location. The toilet flange is at the exact center between the two bolts. Mark the exact center from one bolt to the next with a piece of tape or a non-permanent marker, keeping in mind that the toilet is in the way. Mark the estimated location on the seat or tank (whatever makes the most sense).
Grab your tape measure and go from the center of the toilet flange to the adjacent walls. Don’t go to the corner where the walls meet. Instead, extend outward at a 90-degree angle toward the walls on the right and left of the toilet. Use a measuring square or framing square to ensure an exact angle.
Find where both measurements intersect, which should match up with the center of the toilet flange. Again, double- and triple-check your work to ensure accuracy, especially if your readings indicate a measurement outside the norm.
The rough-in isn’t the only important measurement. To get your complete toilet dimensions, you’ll also need a variety of figures like bowl width and length. These help ensure your toilet fits in the space with proper clearance. You’ll need at least 21 inches of clearance in front of your toilet and 15 inches on either side (measured from the center of the toilet).
Here are common dimensions, though they vary from toilet to toilet:
Seat height: 15–19 inches
Tank height: 27–32 inches
Width: 13–21 inches
Depth: 25–32 inches
Toilets also have a standard drainpipe size of 3 inches, though some toilets may have a 4-inch pipe.
Measuring a toilet rough-in distance is a fairly simple process, but you absolutely need an accurate measurement to avoid buying the wrong fixture for your bathroom. Here are some tips to get it right.
Don’t measure from the baseboard (account for it instead). The baseboard runs perpendicular around the floor and is ½ inch thick, which can throw off your measurements. Start from the bare wall just above the baseboard and adjust for height. If you have to integrate the baseboard, measure the width and add that to the total measurement.
Toilet bolt caps are finicky and can misalign with years of use. Don’t measure the bolt cap if it’s not aligned correctly. The bolt cap should be centered on the discharge hole. If it seems off, it probably is. Realign the bolt caps before conducting any measurements, or take the misalignment into account.
Do you have an elongated or oddly-shaped toilet? Don’t worry, as this does not automatically indicate a larger or unique rough-in distance. These toilets still feature 10-inch, 12-inch, and 14-inch rough-ins.
An elongated toilet doesn’t necessarily require a larger rough-in. For the most part, whether the toilet is elongated or round doesn’t make a difference for the rough-in distance.
You won’t need a pro if you plan to purchase and install a toilet yourself. However, having one on speed dial certainly comes in handy, particularly regarding the rough-in distance. You will most likely have a smooth installation process if you conduct your measurements and get 12 inches or even 10 or 14 inches.
However, if you keep getting funky measurements outside of the norm, hire a toilet installation service near you for some help. Certain bathroom designs necessitate custom-made toilets to accommodate the rough-in. In an absolute worst-case scenario, if a pro recommends moving the drainpipe itself, it is definitely not a DIY project. The cost of professional toilet installation is between $225 and $550.
Most toilets have a 12-inch rough-in or hole, but some have 10- or 14-inch holes, which means that not all toilets fit all setups. Knowing how to measure the rough-in is essential, so you purchase a toilet that fits the existing drain hole. It can be costly to have the rough-in moved, and most stores don’t accept toilet returns.
The toilet should rest 10, 12, or 14 inches from the back wall. As for other clearances, 15 inches is the minimum distance from the flange to any side wall or nearby fixture, including the shower, tub, and sink. Modern codes also require at least 24 inches of clear space in front of the toilet.
If you’re replacing your toilet, you cannot replace a 10-inch rough-in toilet with a 12-inch one. A 12-inch rough-in toilet doesn’t fit in a bathroom with a 10-inch rough-in size without some major updates to your plumbing. However, a 10-inch rough-in toilet fits into a 12-inch rough-in with the addition of a longer connector. In most cases, it’s easier to match the new toilet with the rough-in distance.
Ensuring your toilet will fit starts with measuring the rough-in, but there are a few other factors to consider. The toilet tank's height and the toilet's depth should fit comfortably within the bathroom’s current setup. When considering depth, look at the walking space around the toilet to ensure it fits in the bathroom.
