Editorial policy

By the Plankley team · Last checked 19 October 2026

Sources

Every default figure in a calculator has a kind (typical value, our assumption or common UK size), a source where it has one, and the date it was checked. Rules about planning, building regulations and safety link to the official source.

Checking

Before a page goes live, a second person checks its figures against manufacturer or supplier data and its rules against official guidance. If a page changes after that check, it's checked again.

What we don't do

• We don't test products and never claim to.
• We don't show live prices. A cost appears only when you type in your own price.
• Advertising never changes a formula, a default figure or what we include.