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We read every message. The best ways to help us:

Report an error — tell us which calculator, the numbers you entered, and what you expected.
Suggest a calculator — describe your project and what you needed to work out.
Product data — if you're a manufacturer or supplier with published coverage or yield figures, we'd like to cite them.

We can't give site-specific engineering or building advice. For structural work, follow local building codes and consult a qualified professional.