Inputs
in
Measured from backing to top of pile.
in
Set to 0 if no cushion. Use firm cushion on accessible routes.
Softer cushions compress underfoot and may warrant additional safety margin.
Use for stairs: wrapping over nosing increases perceived thickness. Set to 0% for flat areas.
in
If the margin to the limit is below this, label as “Caution”. Defaults ≈ 1/16 in (1.6 mm).
Auto‑recalculate
Results
Status
Safety margin
0.00 in / 0.00 mm
Positive = under limit; negative = over limit.
Effective pile
0.00 in / 0.0 mm
Includes nosing wrap factor.
Applicable limit
0.50 in / 12.7 mm
Adjusted for cushion firmness where relevant.
Supplementary checks
Example data table
| Scenario | Pile (in) | Pad (in) | Context | Nosing wrap % | Status |
|---|---|---|---|---|---|
| Residential stair | 0.45 | 0.25 | Stairs | 10 | Safe |
| Commercial stair dense pad | 0.51 | 0.20 | Stairs | 10 | Caution |
| Accessible corridor | 0.40 | 0.30 | Accessible | 0 | Safe |
| Door threshold unbeveled | 0.30 | 0.00 | Door (unbeveled) | 0 | Not recommended |
| Door threshold beveled | 0.48 | 0.00 | Door (beveled) | 0 | Caution |
Formula used
- Effective Pile Height = Pile Height × (1 + Nosing Wrap % / 100)
- Applicable Limit depends on context:
- Stairs: 0.50 in (13 mm) maximum pile
- Accessible routes / ramps: 0.50 in (13 mm) maximum pile
- Door threshold (unbeveled): 0.25 in (6.4 mm) maximum vertical change
- Door threshold (beveled): 0.50 in (13 mm) maximum vertical change
- Firmness Adjustment: if cushion is soft, reduce limit by 1/16 in (≈1.6 mm); if medium, reduce by 1/32 in (≈0.8 mm); if firm, no change.
- Safety Margin = Applicable Limit − Effective Pile Height
- Status Logic:
- Safe if margin ≥ tolerance
- Caution if 0 ≤ margin < tolerance
- Not recommended if margin < 0
These thresholds mirror widely used industry practices for safety and accessibility. Always confirm local building codes, project specifications, and manufacturer guidance.
How to use this calculator
- Select your measurement units.
- Enter carpet pile height and any cushion thickness. If none, set cushion to 0.
- Choose the compliance context that matches your situation (stairs, accessible route, or door threshold type).
- For stairs, adjust the nosing wrap percentage to reflect wrapping over the nosing.
- Set your caution tolerance band. The default is about 1/16 inch.
- Review the status, safety margin, and supplementary checks. Adjust inputs as needed to achieve a Safe result.
- Export results as CSV or PDF for submittals, site notes, or documentation.
Tip: On accessible routes, choose firm cushions and secure edges to minimize trip risk and rolling resistance.
FAQs
A common maximum is 0.5 in (13 mm) pile on stairs. If wrapping over a nosing, consider perceived thickness and keep a safety margin to account for measurement variation and cushion compression.
Yes. Softer, thicker cushions increase perceived thickness and can reduce effective safety margin, especially at transitions and stairs. Firm, dense cushions are preferred for accessibility and edge stability.
Unbeveled vertical changes present a sharper step. A lower limit (about 0.25 in) helps reduce trip risk. A bevel provides a ramped transition, allowing up to about 0.5 in.
A common choice is 1/16 in (≈1.6 mm). Increase it for higher risk areas or where measurement variability is expected; decrease it when specifications are tightly controlled.
Limits usually reference pile thickness to the backing for carpeted areas. However, pad characteristics influence perceived height and stability. Use firm pads and secure edges, especially at transitions.
No. It’s a screening aid. Always verify with local codes, contract documents, and manufacturer instructions before final decisions or submittals.
Use the CSV or PDF export buttons to capture inputs and computed outputs. Attach the file to your takeoff package, method statement, or product data sheet.
Quick notes
- Keep pile height at or below the applicable limit for the chosen context.
- Prefer firm, dense cushions for accessibility and edge stability.
- Secure edges and transitions; avoid abrupt changes in level.
- Measure on a flat surface to the top of pile; include wrap effects on stairs.
- Retain exported CSV/PDF with your estimate or install plan.
Unit conversion
1 in
25.4 mm
1 mm
0.03937 in