Response time
We usually reply within 2–3 business days.
Found a wrong number?
Choose “Report a calculation error” and include the page and the values you entered.
Before you write
- Calculator questions: each calculator page explains its formula, defaults and a worked example, and our methodology page lists every assumption. That often answers “why is my number different from my supplier's?”
- Project advice: we can explain how our calculators work, but we cannot give engineering advice for a specific site. For structural, drainage or load-bearing work, please consult a qualified local professional.
- Privacy requests: to see, correct or delete information you sent us, choose “Privacy or data request”. See our privacy policy for details.
- Advertising and partnerships: we do not accept payment to change calculator results or recommendations.
How we use your message
We use the details you send only to read and answer your message. We do not add you to a mailing list or sell your information. Messages are kept for up to 24 months and then deleted. Read the full privacy policy.