Questions about a calculator, a formula, or the site: send an email. There is no contact form and no account system.
Last reviewed 19 August 2026
Email the operator of runnerslab.app at yanchi@yanchi.space.
That address is the right place for methodology questions, bug reports, and privacy requests. Replies are not guaranteed to be immediate. Do not send medical questions; the calculators are not medical advice.
Unit preference and last 5K, 10K, half, and marathon target times stay on this device. Accept to let Google Analytics measure visits. Advertising is not used.