Nosing Radius & Overhang Compliance Calculator

Verify stair safety by measuring nosing radius and overhang then compare to selected code limits with clear pass or fail guidance. Convert units add multiple samples save CSV or PDF and document compliance projects supports IBC IRC presets custom thresholds and detailed notes for audit trails and client reports on any job you tackle

Inputs

mm
mm
mm
mm
mm
mm
mm

Result

R ≤ Rmax
Omin ≤ O ≤ Omax
Bevel ≤ Bmax
Overall

Thresholds here reflect widely used limits. Always confirm with the authority having jurisdiction.

Samples & Exports

# Unit Preset R O Bevel R ≤ Rmax O range B ≤ Bmax Overall Notes

Tip: add each measurement after verification to build a project record you can export.

Example data

We’ve prefilled three realistic samples to illustrate pass and fail cases. Replace with your measurements.

  • Sample 1: R=6 mm, O=28 mm, Bevel=2 mm → Pass
  • Sample 2: R=12 mm, O=30 mm, Bevel=2 mm → Fail (radius too large)
  • Sample 3: R=5 mm, O=12 mm, Bevel=2 mm → Fail (overhang too small)

Formula used

The calculator checks measured values against threshold limits and reports per‑criterion and overall compliance.

1) Radius compliance: R ≤ Rmax
2) Overhang compliance: Omin ≤ O ≤ Omax
3) Bevel compliance (optional): B ≤ Bmax
4) Overall: ALL(true) of 1..3 (ignores #3 if no bevel entered)

Typical industry presets (confirm locally): Rmax ≈ 9.5 mm (3/8 in); O range ≈ 19–38 mm (3/4–1‑1/2 in); Bmax ≈ 12.7 mm (1/2 in).

Unit conversion uses 1 in = 25.4 mm. All thresholds are stored internally in millimeters; inch inputs are auto‑converted.

How to use this calculator

  1. Select your unit (mm or in) and a code preset. Choose Custom to set your own limits.
  2. Enter measured nosing radius (R), overhang (O), and optional bevel.
  3. Click Check compliance to see per‑criterion results and the overall pass/fail banner.
  4. Add each checked measurement to the table to build a record. Include a short note for traceability.
  5. Export your table as CSV or PDF for submittals and project files.

Disclaimer: Building codes vary by jurisdiction and edition. Use this as a documentation aid, not a legal determination. Consult the AHJ for final requirements.

FAQs

It is the curvature of the stair tread edge. A smaller radius creates a crisper edge; many codes cap this radius so the nosing is not overly rounded.

The projection of the tread beyond the riser below. Codes typically require a minimum and maximum projection for safety and consistency.

A large bevel at the nosing can reduce effective projection or create a slip hazard. Many standards cap bevel depth at or near 1/2 in (≈12.7 mm).

Pick the edition enforced by your local authority. If uncertain, ask the designer or building official. You can also set custom thresholds matching the approved drawings.

Yes. Measure after carpet installation for final values, or adjust measurements to reflect the finished edge if checking sub‑treads before covering.

Use at least 0.5 mm or 1/32 in resolution. Take several readings and use the worst case. Record your method and any photos in the notes.

Yes. Choose Custom and set limits to match project specifications, historic codes, or test protocols. The table export will include your chosen limits.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.