MEASURE ONCE. PLAN YOUR PURCHASE.

Underlayment calculator.

Estimate underlay packs by effective area or rolls from room width and your specified seam overlap.

FLOORING

Your inputs

Measurement schematic, not to scale. Use your own dimensions and product specification.

Use measurements from your plan and properties from your chosen product. Any prefilled values are illustrative.

Underlay supply format

Length

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Width

Where to get this value

Measure this dimension in your plan or on site and use the displayed unit. For irregular shapes, divide the geometry into the supported sections.

Effective coverage per roll / pack

ft²

Use usable coverage after any specified overlaps.

Where to get this value

Use the actual usable quantity or dimensions of the product you intend to buy. Check the label and the unit shown here.

Waste allowance

Shortcuts only; choose your own allowance above.

Where to get this value

Enter your own allowance. Presets are input shortcuts, not a construction recommendation.

YOUR ESTIMATE

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A clear estimate starts here.

Enter your dimensions and product details to see the quantity and purchase breakdown.

KEEP YOUR PROJECT TOGETHER

Plan the full project.

Reuse your dimensions, add the other materials and build a purchase list.

Open Flooring project

Formula and assumptions

BEHIND THE NUMBERS

How this calculation works.

Pack mode uses supplied usable coverage. Roll mode lays strips along the room length, deducts your specified overlap at each side seam and permits end-to-end joins. Whole rolls are ordered; cutting and join locations are not optimised. Unlike the floor-covering tool, this estimates the separate underlay layer and its seams.

Packs = ceil(area × allowance / pack area); rolls = ceil(overlapping strip length × allowance / roll length)Calculated with normalised units