Rowing 2K Time Predictor

Paul’s Law — the most-used formula in rowing

Paul Smith published the rowing equivalent of Riegel’s running prediction in the early 1990s. The relationship between time and distance for trained rowers follows a power law:

time_2 ÷ time_1 = (distance_2 ÷ distance_1) ^ 1.06

The 1.06 exponent is the magic number. It says doubling the distance roughly doubles the time, but with a slight penalty (about 4%) because race pace falls as duration rises. Trained rowers fit this curve remarkably well — within ±2 seconds across the 500m to 5000m range — which is why coaches still trust it 30+ years on.

What the predictions actually look like

For a 1:34.5 over 500m, Paul’s Law predicts a 2K of about 6:34.

So a 19:55 5K at the same fitness level as the 2K. If your 5K is faster than the prediction says, your 2K is undertrained on the top end. If it is slower, you have a fitness gap on the long-aerobic side.

Where the formula breaks

Paul’s Law assumes the rower is trained and pacing well. It overestimates 2K from a 500m if the sprint was a redline all-out PR — short pieces include alactic and creatine-phosphate energy that won’t carry to 2000m. It underestimates 2K from a long aerobic piece if pacing was conservative.

A more robust prediction uses two tests at different distances, and refits the exponent. Heavy rowers with strong anaerobic capacity sometimes fit closer to 1.08; lightweights with pure aerobic ability often fit 1.04 to 1.05.

What to do with the number

Predict your 2K, then train the gap. If the predictor says 6:45 and you can only hold 7:00 in a race, the gap is mental, pacing, or race-day taper, not fitness. If the predictor says 6:45 and your last 2K was 6:30, you have improved between tests — re-test soon to update the baseline.

The Concept2 logbook keeps a “best of all time” by distance which makes for a built-in Paul’s Law audit.