How to Measure for a Stair Handrail

Getting accurate measurements before ordering a stair handrail saves time, money, and frustration. This guide covers everything you need to measure for both wall-mounted and ground-mounted handrails.

What You Will Need

  • Tape measure (25-foot minimum)
  • Pencil and notepad
  • Level (4-foot recommended)
  • A helper (optional but useful for long runs)

Measuring for a Wall-Mounted Handrail

1. Measure the Total Stair Run

Measure the horizontal distance from the face of the bottom riser to the face of the top riser. Then measure the vertical distance (total rise). The actual handrail length you need is the slope distance — the diagonal measurement along the stair slope.

Quick formula: Slope length = square root of (run² + rise²). For a staircase with a 10-foot run and 8-foot rise, the slope length is about 12.8 feet.

Or simply hold a tape measure along the stair slope from the bottom nosing to the top nosing and add 24 inches for the required top and bottom extensions.

2. Determine Handrail Height

Measure vertically from the stair nosing (the front edge of the tread) to where you want the top of the rail. Building code requires 34 to 38 inches. Most people find 36 inches to be the most comfortable height.

3. Count Your Brackets

Divide your total handrail length by 4 feet to determine the number of brackets. Round up and add one. For example:

  • 6-foot handrail: 3 brackets
  • 8-foot handrail: 3 brackets
  • 12-foot handrail: 4 brackets
  • 16-foot handrail: 5 brackets

Check out our handrail brackets once you know what you need.

Measuring for a Ground-Mounted Handrail

1. Count Your Steps

Count the number of stair risers (vertical faces). This determines which product size you need. Our single post handrails are designed for 1-3 steps. For longer runs, our ground-mounted railing systems accommodate any stairway length.

2. Measure Step Width

Measure the total width of your stairway. For a single handrail on one side, you only need one railing. For railings on both sides, order two. If the stairs are wider than 44 inches, building code may require a handrail on both sides.

3. Check the Landing

If your stairs have a landing or platform at the top, measure the landing depth. You may need a separate guardrail section for the landing — our assembled railing systems include both stair and level sections.

Measuring for Guardrails and Deck Railings

For level guardrails (decks, balconies, landings):

  • Measure the total linear footage of railing needed
  • Guardrails must be a minimum of 42 inches tall (different from stair handrails at 34-38")
  • Account for corner posts if the railing turns 90 degrees
  • Measure each straight section separately — railings are cut to length per section

Common Measuring Mistakes

  • Forgetting extensions: Code requires the handrail to extend 12" past the top riser. Add this to your measurement.
  • Measuring the wall instead of the slope: Wall length is shorter than the actual handrail needed.
  • Not checking for plumb: Old houses can have walls that lean. Use a level to verify before drilling brackets.
  • Ignoring obstructions: Check for light switches, outlets, or trim that might interfere with bracket placement.

Still Not Sure? We Can Help

Send us your stairway measurements and a few photos and we will recommend the exact products and quantities you need. Contact us here — we respond the same day.