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How to Measure a Toilet Seat

Lowe's Editorial Team

By Lowe's Editorial Team
Updated May 18, 2026

You may need to replace your toilet seat if it has cracks, chips, stains or feels loose. Choosing a replacement without measuring can lead to a poor fit. Use this guide to measure your toilet bowl correctly so you can find a seat that fits securely and comfortably.

Tools and Materials

Tools

Materials

Note

Product costs, availability and item numbers may vary online or by market.

Key Takeaways

  • Measure your toilet bowl (not the seat) to ensure a proper fit before buying a replacement.
  • Identify the shape (round vs. elongated) by measuring from the bolt holes to the front of the bowl.
  • Use these measurements to select a compatible seat; non-standard sizes may require manufacturer-specific options.
  • Avoid common mistakes like guessing the shape, skipping measurements, or measuring the seat instead of the bowl.
  • Replace your toilet seat if it’s cracked, loose, stained or uncomfortable.

Step-by-Step Guide to Measuring a Toilet Seat

Toilet seats are typically available in two standard shapes: round and elongated. These terms refer to the shape of the toilet bowl rather than the seat itself. So, it’s important to match the seat to your bowl.

Step 1: Measure the Bowl Length

  1. Lift the seat and lid.
  2. Locate the bolt holes where the seat attaches to the bowl.
  3. Measure from the center point between the bolt holes straight to the front edge of the bowl.

Typical Measurements:

  • Round Bowls: About 16-1/2 inches
  • Elongated Bowls: About 18-1/2 inches

Tip

These are standard ranges. Always measure your toilet exactly to confirm the dimensions before purchasing a new one.

Step 2: Measure the Bowl Width

Measure across the widest point of the bowl, from outer edge to outer edge. Width is typically around 14 to 14-1/2 inches for most standard toilets.

Step 3: Measure the Bolt Hole Spacing

Measure the distance between the centers of the two bolt holes at the back of the bowl. The standard spacing is 5-1/2 inches.

Step 4: Choose the Right Seat

Use your measurements to select a compatible seat:

  • If the length is around 16-1/2 inches, choose a round toilet seat.
  • If the length is around 18-1/2 inches, choose an elongated toilet seat.

If your measurements differ significantly, you may have a non-standard or specialty toilet. In that case, check the manufacturer’s specifications or look for seats designed for that model.

Common Mistakes to Avoid

  • Measuring the Seat Instead of the Bowl: Always measure the bowl for an accurate fit.
  • Skipping Bolt Spacing: While usually standard, confirm to avoid fit issues.
  • Guessing the Shape: Even small differences can affect comfort and fit.
  • Ignoring Features: If upgrading to features like soft-close or heated seats, verify compatibility with your measurements.

Frequently Asked Questions

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