Convert split,
watts & km/h
Concept2 pace-to-watts conversion. Enter a 500m split or a full piece (time + distance), get watts, km/h, pace per 1km, and projections across standard race distances.
Quick answer
watts = 2.80 / (split / 500)³ · km/h = (500 / split) × 3.6. The cubic relationship means a 5% faster split costs ~16% more power. A 1:30 split = 480 W, 1:45 = 305 W, 2:00 = 200 W. The calculator works in either direction — start from a split or from a full piece (time + distance).
Pace / watts reference
| 500m split | Watts | km/h | 2K total | 6K total |
|---|---|---|---|---|
| 1:30.0 | 480 W | 20.00 | 6:00 | 18:00 |
| 1:35.0 | 408 W | 18.95 | 6:20 | 19:00 |
| 1:40.0 | 350 W | 18.00 | 6:40 | 20:00 |
| 1:45.0 | 302 W | 17.14 | 7:00 | 21:00 |
| 1:50.0 | 263 W | 16.36 | 7:20 | 22:00 |
| 1:55.0 | 230 W | 15.65 | 7:40 | 23:00 |
| 2:00.0 | 203 W | 15.00 | 8:00 | 24:00 |
| 2:05.0 | 179 W | 14.40 | 8:20 | 25:00 |
| 2:10.0 | 159 W | 13.85 | 8:40 | 26:00 |
Frequently asked questions
What is the Concept2 pace-to-watts formula?
watts = 2.80 / (split_seconds_per_500 / 500)³. The cubic relationship is the important part — small pace gains require disproportionately more power. Going from 1:50 to 1:45 (a 4.5% pace gain) costs about 14% more watts.
Why does the Concept2 PM5 sometimes show a different watts number than I see here?
The PM5 uses the same formula. Differences usually come from monitor calibration drift, drag-factor changes between sessions, or different rounding (the PM5 displays integers; this calculator computes to floating-point internally). For matched conditions, the values agree exactly.
Does my drag factor change the watts?
No. Concept2's ergometer is a "brake-style" design: the drag factor changes how the flywheel feels stroke-to-stroke (more like rowing in heavy vs light water), but the watts calculation depends only on flywheel deceleration rate, not drag setting. Two rowers pulling 250W at drag 110 vs 130 are doing the same physical work — the second is just doing it with a heavier, slower stroke.
How do I convert watts back to split?
split (s/500m) = 500 × (2.80 / watts)^(1/3). Toggle this calculator to "500m split" mode and enter your target pace — the watts panel updates instantly. You can iterate splits to land on a watts target (e.g. "what split holds 250W?" → ~1:50.4).
How is km/h derived?
km/h = (500 / split_seconds) × 3.6. Useful for cross-comparing erg pace to on-water speed (a 2:00 split = 15 km/h = 4.17 m/s). Real on-water rowing has wind/current/efficiency variance, so erg km/h is an idealised reference.
What about the race-distance projections?
They project your input pace linearly across standard distances: total = (distance / 500) × split. Useful for "if I held this split…" mental math. Real races have pacing variation — start higher, settle, sprint — so the projection is a flat-pace baseline rather than an actual performance prediction.