The site
Runners Lab at runnerslab.app is a free, English-language collection of running calculators operated by the operator of runnerslab.app. There are no accounts. Use of the calculators is at your own risk.
Training guidance, not professional advice
Results are for training guidance only. They are not medical advice, nutritional advice, physiotherapy, or a coaching relationship. Do not start, intensify, or continue training based solely on a number from this site if you have a health condition, injury, or any doubt. Consult a qualified professional.
Estimates versus exact arithmetic
Some tools are exact arithmetic: pace, time, distance, speed, and even splits, given the numbers you enter. Other tools are models: race prediction (Riegel), training paces (Daniels VDOT), heart-rate zones (Tanaka, %HRmax, Karvonen), grade-adjusted pace (Minetti), and age grading (interpolated WMA 2015 factors). Models are estimates. They can be wrong for you. Read the methodology.
Acceptable use
Do not misuse the site, attempt to disrupt it, or scrape it in a way that harms the service. Calculator pages may be linked to and cited. Republishing the engines or the age-grading tables as your own dataset is not allowed without permission.
No warranty
The site is provided as is. We do not warrant that a result is accurate for your race, your body, or your course. You are responsible for how you use the numbers.
Changes
Formulas, pages, and these terms can change. The current version is the one published at this URL. Questions: yanchi@yanchi.space.