Contact

Email: hello@example.com — replace this with your real address before you publish, and use an address on your own domain rather than a free mailbox.

If you are reporting a number that looks wrong, it helps enormously to include the material, the figure you expected, and where it came from — a bag label, a supplier quote or a spec sheet. Regional variation is real and we would rather widen a range than argue with it.

If there is a material you keep having to work out by hand, say so. The calculators are generated from a single data file, so adding one is usually a small job.