Pick the split type, enter your time, and the calculator returns an equivalent 40-yard dash. Useful when you've measured a flying 10 or a 10–40 segment with a timing system but want to compare against a standard 40 time.
What this calculator is doing
The Tru40 calculator fits a mono-exponential sprint model to your single split — the same model used in modern sprint diagnostics (Furusawa, Hill & Parkinson 1927; Samozino & Morin 2015–2016). From a flying-10 or a 10–40 split, the calculator solves for the athlete's maximum sprint speed (MSS), assuming a population-typical acceleration profile calibrated against published NFL Combine data (Clark et al. 2017). With MSS fitted, it then predicts the full 0–40 yard time.
A few practical notes:
- Hand timing reads fast. Stopwatch reaction adds 0.20–0.30 s versus electronic timing. The calculator can't tell which you used.
- Start technique matters. The model assumes a standing or three-point start at rest — a track-block start, rolling start, or extra runway will throw the estimate off.
- The Tru40 estimate isn't a measured 40. Compare estimates against other estimates over time. Use a measured 40 when you need the actual number.
Want this built into your testing workflow?
Performance House logs every sprint test with both the raw split and the Tru40 estimate side-by-side. The Performance Index uses the Tru40 (so an athlete who only runs a flying 10 still gets a comparable speed sub-score), and the trend chart plots the estimate over time. The same calculator code runs in the platform and on this page — same model, same answer.
For more on the science, see the full Tru40 guide.