About ArchCalc

ArchCalc is a free collection of precision calculators for the building professions. It was created to replace the scattered spreadsheets, dog-eared formula sheets and half-remembered conversions that architects and engineers juggle every day with one fast, reliable web app.

The toolkit covers the calculations that come up constantly in practice — converting drawing scales, sizing stairs and ramps, estimating materials and cost, and working out areas, roof pitch and Floor Area Ratio. Each tool is designed to be obvious to use: enter what you know, read off what you need, and get back to designing.

Our principles

• Free and open: no signup, no paywall, no download.
• Private by design: calculations run in your browser; your inputs stay on your device.
• Fast: a static, lightweight site that loads instantly anywhere.
• Honest: results are well-founded guidance, always to be verified against local codes.

Have a calculator you wish existed? We are always adding tools — head to the contact page and tell us.