Square footage calculator.
Calculate square footage from length and width in seconds. Enter the two dimensions for any room, slab, roof plane or site area, and this calculator finds the area instantly — no rows to add, no upload needed, just type and read the result. Switch between metric and imperial units at any time; whatever you've already entered converts automatically. This is a straightforward length by width calculation, not a substitute for measuring an irregular or multi-section space, which needs breaking down into simpler rectangles first. Use our Cubic Yard Calculator if you also need a depth to convert that area into a volume.
How we calculate this.
Calculate square footage from length and width in seconds. Enter the two dimensions for any room, slab, roof plane or site area, and this calculator finds the area instantly — no rows to add, no upload needed, just type and read the result. Switch between metric and imperial units at any time; whatever you've already entered converts automatically. This is a straightforward length by width calculation, not a substitute for measuring an irregular or multi-section space, which needs breaking down into simpler rectangles first. Use our Cubic Yard Calculator if you also need a depth to convert that area into a volume.
area = length × width. Recomputes instantly on every change, no "Calculate" button needed.
| Assumption | Value | Source |
|---|---|---|
| Area formula | length × width | Basic geometry — the area of a rectangle is its length multiplied by its width. |
This is an early-appraisal planning estimate, not a quotation or a substitute for a surveyed takeoff. Last reviewed 31 Aug 2026.
Multiply length by width, both in the same unit — this calculator does that instantly and lets you switch between metric and imperial.
Break it into rectangles, calculate each one separately, then add the results together — this calculator handles one rectangle at a time.
Yes — switch to metric with the toggle above and enter your dimensions in metres.
Yes — use the metric/imperial switch above the calculator. Values you've already entered convert automatically; nothing is lost switching back and forth.
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