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Have a question about a calculation or found an error in a guide?

Email

Write to [email protected]. Please include the page URL, the measurements you entered and what you expected to see. Do not send payment information or sensitive personal details.

What we can help with

  • Reporting a broken calculator or incorrect example.
  • Suggesting a project calculation that would be useful to makers.
  • Asking about site content or privacy.

Calculator estimates are general planning aids. We cannot inspect your materials or guarantee the outcome of an individual project by email.