Erg Watts to Split Converter

The Concept2 cubic relationship

Every Concept2 erg uses one equation to convert between power and pace:

watts = 2.80 ÷ (split ÷ 500) ^ 3

where split is in seconds per 500m. The flip:

split_seconds = 500 × (2.80 ÷ watts) ^ (1/3)

Why a cube? Because water resistance, and Concept2’s air resistance which mimics it, scales with the cube of velocity. To row twice as fast you need eight times the power. The PM5 monitor does this math hundreds of times per second; the calculator above does it once.

Reference table: the splits and watts every rower memorises

Look at what the cube does at the bottom of that table. Going from 1:30 to 1:15 is fifteen seconds, and it costs you 350 extra watts, more than the entire output of the 2:00 steady-state row. That is why the last ten seconds of a 500m sprint feel the way they do, and why shaving two seconds off a 2K split is a genuinely different project from shaving two seconds off a 5K.

The watts column is “average watts the flywheel sees.” Power on the handle is higher; the difference is drivetrain efficiency, fan damping setting, and the impossibly short recovery between strokes.

Damper setting does not change the formula

A common beginner question: does damper setting change watts? No. The same wattage produces the same split regardless of damper. What changes is how the stroke feels (heavier or lighter) and the optimal stroke rate. Most coaches set damper 3 to 5 for endurance work, 5 to 7 for power work. Setting it to 10 turns the erg into a strength training tool, not a rowing simulation.

Why bigger rowers go faster

Power-to-weight is meaningless on a stationary erg. Absolute power wins, and bigger rowers produce more absolute power because they have more muscle mass. A 200 lb collegiate rower pulling 350 watts in a steady-state piece is rowing at 1.75 watts per kg, which is solid rather than exceptional. A 130 lb lightweight pulling the same 350 watts is at 2.96 watts per kg. On the water, where the boat carries less weight, that lightweight is more competitive than the absolute number suggests.

The PR rule

If you have a strong PR over 2K and want to know what watts to hold for a 5K, multiply your 2K watts by about 0.85. For a 10K, multiply by about 0.75. For a 60-minute test, roughly 0.66.

Those factors are not guesses; they fall straight out of Paul’s Law, the time-versus-distance power law rowing coaches use. Paul’s Law says a 5K takes (5000 ÷ 2000)^1.06 = 2.64 times as long as a 2K, which makes the 5K pace 5.7% slower, and the cube turns that 5.7% into a 15% cut in watts. The same arithmetic gives 0.75 at 10K.

A useful sanity check: if your actual 5K watts are well below 0.85 of your 2K, your aerobic base is the limiter. If they are above it, your 2K is leaving something on the table at the top end.