Introduction
Replacing a toilet seat is a relatively easy home improvement project that can quickly update the look of your bathroom. A key step when replacing a toilet seat is understanding how to properly measure the toilet to ensure you purchase the correct size seat. There are a few simple techniques for measuring a toilet that will guarantee you get the right fit.
In this comprehensive guide, we will cover everything you need to know about measuring for a new toilet seat. You will learn the different toilet shapes and sizes, the basic steps for measuring, and tips to ensure accurate measurements. With the right information, you can confidently measure your toilet and select the perfect new seat.
What Toilet Shapes and Sizes Should I Know?
There are two main toilet shapes to be aware of – round and elongated. Within those shapes there are some standard toilet seat sizes:
Round Toilet Seats:
- 16.5 inches – Fits smaller, compact round toilets
- 18.5 inches – Standard size for most round toilets
Elongated Toilet Seats:
- 16.5 inches – Less common size, fits more compact elongated toilets
- 18 inches – Common standard for elongated toilets
- 20 inches – Larger elongated seats
Some less common sizes also include 14 inches and 15 inches for petite round toilets, and 19 inches for extra large elongated toilets.
The most common toilet seat size is the 18.5 inch round or 18 inch elongated. But the specific measurement of your toilet could vary. That’s why measuring accurately is a key factor for getting the right fit.
How to Measure a Round Toilet
- Use a soft tape measure. A soft, flexible tape measure is best so it can curve around the bowl shape.
- Measure from the back of the toilet rim to the very front. Place one end of the tape at the rearmost part of the toilet rim. Then bring the tape along the outer rim to the front and note the measurement. Round up to the nearest 0.5 inch.
- Repeat measurements at several points. To ensure accuracy, take 3-4 measurements at different spots around the toilet rim from back to front.
- Average the measurements. Now add up your different measurements and divide by the number to get the average. This gives you the most accurate overall toilet seat size.
- Consider seat size options. Based on your measurement, you can select the appropriate round toilet seat size – either 16.5 inches or 18.5 inches most likely.
Measuring an Elongated Toilet
Measuring an elongated toilet is nearly the same process as a round bowl:
- Use a soft measuring tape. Be sure the tape measure can curve around the contours of the toilet bowl.
- Measure front to back along the rim. Place one end at the front-most part of the toilet rim and bring the tape along the outer rim edge to the back.
- Take measurements in several spots. Take 3-4 measurements from different starting points on the rim from front to back.
- Find the average length. Add up the measurements and divide by the number taken to determine the overall average length.
- Pick the right elongated seat size. Based on your average toilet measurement, select an elongated seat in either 16.5″, 18″, 19″, or 20″ size.
Tips for Accurate Toilet Measurements
Taking accurate measurements is crucial for finding a well-fitting toilet seat replacement. Here are some helpful tips:
- Remove the existing toilet seat first if possible. This gives you the most precise measurement of the actual toilet bowl dimensions.
- Have a helper. Taking measurements from the side of the toilet on your own can be tricky. Have someone assist with holding the tape measure if needed.
- Note the overhang. Pay attention to how much the old seat hangs over the front and back of the bowl, and purchase a new seat with similar overhang.
- Don’t include bolt caps. Bolt caps on the side of the toilet extend past the actual rim edges so be sure not to include them in measurements.
- Measure in multiple spots. Taking several measurements in different spots accounts for variances in the toilet shape.
- Mind the gaps. If there is a large gap between the rear of the old seat and the tank, get an extended toilet seat to fill in that space if desired.
How to Measure for a Toilet Seat
Follow these full step-by-step instructions to accurately measure your toilet bowl in order to get the perfect replacement seat:
What You Need
- Soft measuring tape
- Notepad or your phone to record measurements
- Flashlight if measuring in dim lighting
Step 1: Remove Existing Toilet Seat
If possible, fully remove the old toilet seat from the toilet bowl first. This gets you the true bowl dimensions without the seat in the way.
Use a screwdriver to remove the seat mounting bolts from the side of the bowl. These are normally towards the back of the toilet seat hinges.
Lift the seat straight up once the bolts are removed. Set the old seat aside to compare sizing and overhang later.
Step 2: Prep Toilet Bowl for Measurement
With the old seat fully removed, inspect the top of the toilet bowl where the seat rests. Remove any dirt or debris that may interfere with placing the measuring tape.
Shine a flashlight inside the bowl if lighting is dim. This helps you see the full rim shape clearly when taking measurements.
Step 3: Measure Front-to-Back Length
Place the end of the measuring tape at the rearmost part of the toilet bowl rim where it meets the tank. Stretch the tape along the rim towards the front following the bowl’s curve.
Note the measurement at the very front of the bowl rim. Round up to the nearest 0.5 inches.
Step 4: Measure Sides
Now place the end of the measuring tape at one side of the toilet rim. Stretch the tape fully across the bowl to the opposite side. Again round up as needed.
Repeat on the other side as well starting at the opposite point on the rim. Take note of both side measurements.
Step 5: Take Multiple Measurements
To confirm accuracy, take 3-4 additional front-to-back and side-to-side measurements at different starting points along the rim.
Be sure to consistently follow the rim shape with the measuring tape on each one. Record all the measurements.
Step 6: Calculate Average
Add up all the front-to-back measurements you took and divide by the number to get the average length.
Do the same with the side measurements to get the average width. These provide the real dimensions of your toilet.
Step 7: Compare to Toilet Seat Sizes
Look at the average length and width measurements compared to standard toilet seat sizes:
- Round seats: 16.5″, 18.5″
- Elongated seats: 16.5”, 18”, 20”
Select the closest larger standard seat size to your averages. This ensures a proper fit.
Step 8: Consider Overhang
Hold up your old seat to the measured toilet bowl. Take note of how much the seat overlapped the front and back rim.
Look for a similar front/back overhang in the new replacement seat for consistency. Most round seats have 1-2 inches overhang, and elongated 2-3 inches.
With accurate toilet bowl measurements and the right seat size selected, you are ready to shop for the perfect replacement. Follow installation instructions to securely fasten the new seat in place. Take your time when measuring to get the right fit.
Frequently Asked Questions About Measuring Toilet Seats
Here are answers to some common questions people have about measuring for new toilet seats:
How do I know if I have a round or elongated toilet?
If the toilet seat has a oval shape that is curved to extend further towards you, it is an elongated seat. A round seat is a simple circle shape. You can also measure – round seats are normally 16.5″ to 18.5″ while elongated measure 16.5″ to 20″.
Should I measure with or without the old seat installed?
It’s best to fully remove the existing seat first to get accurate bare toilet bowl dimensions. But if that is not possible, just be sure to only measure the actual toilet rim and do not include any overhanging seat portions.
What’s the standard toilet seat size?
The most common toilet seat size is 18.5 inches for round bowls and 18 inches for elongated bowls. But toilets come in a range of sizes, so always measure first to determine your specific toilet dimensions.
Do I need to measure the width between toilet bolts?
The side-to-side width doesn’t need to factor into shopping for a basic toilet seat. Just the front-to-back measurement is needed to get the right fit. But measuring width can help match any oversized toilet bowls.
How do I account for gaps between the tank and seat?
If your old seat didn’t fully close the gap to the tank, purchase an extended length model for the new seat. Look for rear overhang of 3” or more to clear gaps behind the seat.
What’s the easiest way to measure a toilet accurately?
The best method is to remove any old seat, then use a soft tape to measure from the very back to the very front of the toilet rim at several points and average the numbers. Following the rim contour ensures the most accurate measurements.
Conclusion
Finding the right toilet seat size for your toilet bowl is straightforward when you follow the proper measuring techniques. Carefully use a soft tape measure to determine the front-to-back dimensions from rim to rim at various spots around the bowl. Take an average of 3-4 measurements to get the most accurate number. Compare this to standard toilet seat sizes, and allow for appropriate front/rear overhang based on your existing seat. With this simple process for how to measure for a toilet seat, you can feel confident that your replacement model will fit perfectly.