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The radius measured from the centre of the circle.
If you measured across the full width instead, that is the diameter — halve it before entering. Mistaking one for the other overstates the area by a factor of four.
Circular area
314.2 sq ft
Area = π × r², computed exactly. Curved work generates more offcut than rectangular work — allow a wider waste margin than you would on a straight run.
They open the calculator with your figures already in it
Radius to Area Calculator: 314 sq ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Area of a circle A = pi x r^2
Inputs used
- Radius (ft)
- 10
Confidence note: Area = π × r², computed exactly. Curved work generates more offcut than rectangular work — allow a wider waste margin than you would on a straight run.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0
Regulatory standards & verification citations1
- Area of a circle A = pi x r^2
Cite this page
Your workspace
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Going the other way — from a measured radius to an area — is the take-off step for anything round: a circular slab, a tank base, a bandstand deck, a turfed island. The arithmetic is trivial, and the error that costs money is confusing radius with diameter. Because area goes with the square of the radius, entering a diameter by mistake reports four times the true area, which on a concrete pour is an expensive lorry to send away. Measure from the centre, or measure across and halve it. Worth noting too that circular work wastes more material than rectangular work of the same area: sheet goods, pavers and tiles all have to be cut to a curve, and offcuts from the perimeter are rarely reusable, so a waste allowance appropriate to a straight run will leave you short.