Rowing pace to watts calculator

The pace shown on an indoor rower is a speed written as time per 500 meters, which is easy to read but hard to compare across rowers or to relate to training load. Power in watts is the other way to say the same thing, and the two are linked by a cube: a small change of split is a larger change of power. This page converts both ways and shows what a steady pace means for common distances.

How do you convert a 500 m split to watts?

Concept2 gives the formula as watts = 2.80 ÷ pace³, where pace is the time in seconds divided by the distance in meters. A 2:05 split is 125 seconds for 500 meters, a pace of 0.25 seconds per meter, so watts = 2.80 ÷ 0.25³ = 179.2. This is Concept2's own worked example. The calculator does the same for any split you type, such as 1:58.4.

How many watts is a 2:00 split?

202.5 watts. A 1:55 split is 230.1 watts, and 2:05 is 179.2. Going the other way, 100 watts is a split of 2:31.8 per 500 m and 200 watts is 2:00.5. Use the Watts to pace mode of the calculator for any other value.

Why does a few seconds faster take so many more watts?

Pace sits in the formula cubed. A split 1% faster needs about 3.1% more power, and 2:05 to 2:00 (4% faster) costs 23.3 more watts, 13% more power. Seconds are expensive at the fast end of the scale.

What is my 2000 m time at a given split?

At a steady split the 2000 m time is four times the split. A steady 2:05 gives 8:20.0, and the table in the result shows 500 m, 1000 m, 2000 m, 5000 m, 6000 m and 10,000 m. Treat it as a pacing target for the average of a piece, and use the time mode to go back from a result to the split.

How many calories does rowing burn per hour?

A Concept2 monitor shows calories per hour as watts × 4 × 0.8604 + 300, a formula posted by a user on the Concept2 forum and matching the model in Oxford's “Physics of Ergometers” (4 units of chemical energy per unit of work, plus a fixed 300 per hour). At 179.2 W that is 917 cal per hour. Concept2's calorie page says the monitor assumes a 175 lb (79.5 kg) person and gives a body-weight correction: true calories per hour = calories on the monitor − 300 + 1.714 × weight. We read the weight in pounds because 1.714 × 175 comes to the 300; that is our reading, as the page does not name the unit. Other sites print different multipliers, such as 3.6 or 4.2 per watt without the 300, so numbers vary between calculators.

Is this the same on a BikeErg or SkiErg?

We have only checked the formula against Concept2's page for the rower, and the calculator is built for rowing splits per 500 m. Do not use it for other machines unless the maker publishes the same relation.

Worked example: a steady 2:05

Pace = 125 s ÷ 500 m = 0.25 s per meter. Watts = 2.80 ÷ 0.25³ = 2.80 ÷ 0.015625 = 179.2. In reverse, the cube root of 2.80 ÷ 179.2 is 0.25, and 0.25 × 500 = 125 seconds, or 2:05. Over a 2000 m piece that is 4 × 125 s = 500 s, or 8:20. The monitor calorie figure is 917 cal per hour for this power, and for a 175 lb rower the body-weight version is 917; for a heavier or lighter rower it moves with the weight at 1.714 per pound.

Common mistakes and limits

Using the average split of a hard piece as a steady target. By this formula watts depend on the cube of pace, so a piece with big swings in speed needs more average power than the same average speed held steady. Mixing up pace per 500 m with pace per meter. The formula needs seconds per meter; entering 125 instead of 0.25 gives a number a thousand times too small. Treating calories as a measurement. The monitor figure is a fixed linear formula plus a flat 300 per hour, which Jon Williams of Concept2 called their best approximation for keeping alive and awake and going through the rowing motion, in a comment quoted on the Oxford page; it is not a measure of the athlete. Expecting every site to agree. Calculators that use 3.6 or 4.2 per watt and drop the 300 give other values, so compare only like with like. Weight-adjusted scores. This page does not correct times for body weight; we could not open Concept2's weight-adjust page and leave it out rather than guess.

Related pages: pace calculator, calories burned calculator and swim pace calculator.

Sources: Concept2, “Pace/Watts calculator” (watts = 2.80 ÷ pace³, pace = ∛(2.80 ÷ watts), and the 2:05 example) and “Calorie calculator” (175 lb / 79.5 kg reference; true calories per hour = monitor calories − 300 + 1.714 × weight); Concept2 forum, “Unit Conversion” thread, 2006 (calories per hour = watts × 4 × 0.8604 + 300, a user post); University of Oxford, Atmospheric Physics, “The Physics of Ergometers,” section 11 (E = (4W + 0.35t) ÷ 4.2 and the Concept2 comment of August 12, 2004 on the 300 per hour), both secondary sources, the second using 4.2 joules per calorie instead of 4.184. The conversion to km/h and mph is arithmetic. How we check our calculators.