Toilet Too Small? How to Accurately Measure Rough-In Dimensions
Purchasing a toilet that properly fits the bathroom's rough-in space is crucial for functionality and comfort. However, accurately measuring rough-in dimensions can be confusing if you're unfamiliar with the key measurements involved.
What is a Toilet Rough-In?
The toilet rough-in refers to theunfinished plumbing stage where drain and vent piping is installed in preparation for the toilet, before the walls and flooring are completed.
The key measurement here is the horizontal distance between the rear wall studs and the center of the toilet drain or flange where the toilet will connect. This is called the rough-in dimension.
Standard Rough-In Dimensions
Typical toilet rough-in sizes are:
- 10 inches
- 12 inches - Most common
- 14 inches
These standard measurements correspond to the distance between the wall and center of the drain. Knowing your accurate rough-in size is crucial for picking a toilet that will fit the space.
When Should I Measure Rough-In Size?
You have two options for when to measure the rough-in size:
Before the Finished Wall is Complete
If your bathroom remodel has open stud walls exposed, measure from the framing straight back to the toilet drain or flange.
This allows you to identify the rough-in size early, so you can purchase the correctly sized toilet before the finished walls go up.
After the Finished Wall is Installed
For existing bathrooms with finished walls, measure from the wall surface back to the rear connections behind the wall to determine rough-in size.
In either case, it's important to confirm dimensions before committing to a toilet purchase.
Understanding Your Current Rough-In
While 10", 12" and 14" remain the industry standard toilet rough-in measurements, older homes sometimes have non-standard dimensions less than 10" or greater than 14".
If your rough opening falls out of the typical size range, you'll need to check with toilet manufacturers about specialty options to accommodate the smaller or larger space.
Measuring Rough-In Dimensions
For Uninstalled Toilets:
- Locate the toilet drain pipe, usually capped or covered with construction adhesive, attached to the flange in the floor.
- Use a tape measure extended from the rear wall straight back perpendicular to the drain pipe flange.
- Measure from wall framing/finished wall to center of the drain pipe to determine rough-in size.
Be extremely precise with measurements to get an accurate rough-in dimension.
For Installed Toilets:
If measuring an already installed toilet:
- Find the anchor bolts that secure the toilet base to the floor flange.
- Use painter's tape to mark the center point between the bolts and outline the flange position.
- From the rear wall, measure directly perpendicular to the marked center point to determine rough-in size.
Confirm your math, triple check measurements, and re-measure from both walls for accuracy.
Other Key Toilet Measurements
While rough-in size is critical, consider these additional dimensions for a comfortable fit:
Clearances Around the Toilet
Measure from toilet flange to:
- Vanity/cabinets - 18 inches minimum
- Bathtub - 15 inches minimum
- Shower - 15 inches minimum
This ensures enough clearance to access the toilet and comply with codes.
Toilet Height
Measure floor to toilet bowl rim height. Standard is around 15-16 inches, but comfort height models measure 17-19 inches from floor to rim.
Bowl Width & Length
While most elongated bowl toilets are fairly uniform in size, some models run large - up to 16.5 inches wide. Measure to ensure the bowl fits without crowding.
For more tips on finding and installing the perfect toilet, check out our other in-depth guides:
- How to Choose the Right Toilet
- Toilet Buying Guide and Reviews