Underlay Calculator
Estimate underlay rolls from room area and roll coverage.
Quick answer
Enter total floor area and roll size to get underlay roll count with waste.
Try the calculator
Results
- Net floor area
- 20.8 m²
- Order quantity (with waste)
- 22.88 m²
- Underlay (incl. 5% overlap)
- 21.84 m²
- Room perimeter
- 18.4 m
Definition
An underlay calculator works out how many underlay rolls cover a job after waste.
Explanation
Underlay comes in various roll widths and lengths. Carpet underlay differs from laminate underlay in density and acoustic rating.
Worked example
20.8 m² lounge needs 22.9 m² with 10% waste — one 15 m² roll plus one 10 m² roll, or a single 25 m² roll.
Summary
Match underlay type to the floor covering and order slightly over calculated area.
In depth
Matching underlay to the floor covering
Carpet vs hard-floor underlay
Carpet underlay is graded by density and tog rating — higher traffic areas need firmer foam or rubber. Laminate underlay often includes a moisture barrier for ground-floor concrete.
Do not use carpet underlay beneath laminate; it compresses and invalidates click locking over time.
Roll planning
Underlay rolls come in different lengths and widths. Two smaller rolls may cost more labour than one large roll — factor fitting time when comparing supplier prices.
Frequently asked questions
- Can I reuse underlay offcuts?
- Small offcuts can fill cupboards; main rooms need continuous runs for best finish.
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