Erg Calculator

Enter your Concept2 rowing 500m split to see the power output in watts and the calories per hour the monitor reports.

Quick Facts

Formula
watts = 2.80 / (seconds-per-metre)³
Concept2's published pace-to-power relationship; calories use watts × 4 × 0.8604 + 300.

Your Results

Calculated
Power output
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watts at this pace
Calories per hour
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Concept2 monitor rate
Pace
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seconds per metre
2000m projection
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time at this split

Ready

Enter your 500m split and press Calculate.

What the erg calculator does

An "erg" is an indoor rowing (or ski/bike) ergometer — most commonly the Concept2 RowErg. Its performance monitor (the PM5 and its predecessors) reports your effort three ways: as a pace (time per 500 metres), as power in watts, and as calories per hour. This calculator takes your 500m split and converts it into watts and Cal/hr using the exact relationships Concept2 builds into the monitor, so you can compare pieces, plan intervals, and understand what a given split really costs in power.

The formula

Concept2 defines the pace-to-power relationship as:

watts = 2.80 ÷ pace³

Here pace is measured in seconds per metre. Because a 500m split of T seconds means you cover one metre in T/500 seconds, the formula expands to watts = 2.80 / (T/500)³. The relationship is a cube, which is why small improvements in split demand large jumps in power: halving your pace requires eight times the wattage.

Calories per hour come from a second Concept2 formula that layers a resting-metabolism offset on top of the mechanical power:

Cal/hr = watts × 4 × 0.8604 + 300

The +300 term is why the monitor still counts calories when you drift to a near-stop: it approximates the energy your body burns at rest. This is why erg "calories" are always higher than the pure mechanical work would suggest.

Why rowers use watts instead of pace

  • Watts are additive and intuitive. Doubling your training power is a clear target; "dropping your split from 2:00 to 1:53" hides how much extra work that actually takes.
  • Watts let you compare across machines. A watt on a RowErg, BikeErg, or SkiErg is the same watt, so cross-training loads line up even though the paces do not.
  • Pace still rules racing. Standard erg races (2000m, 500m, 5000m) are scored on time, so the monitor keeps split front-and-centre while power runs underneath it.

Common reference points

  • 2:00.0 /500m ≈ 202 watts ≈ 988 Cal/hr — a common steady-state benchmark for a fit recreational rower.
  • 1:45.0 /500m ≈ 302 watts ≈ 1,340 Cal/hr — a strong open-weight training pace.
  • 1:30.0 /500m ≈ 480 watts ≈ 1,952 Cal/hr — roughly elite 2k race territory.
  • 2:30.0 /500m ≈ 104 watts ≈ 656 Cal/hr — an easy warm-up or recovery pace.

Frequently Asked Questions

How is power in watts calculated from a rowing split?
Concept2 ergometers use watts = 2.80 / pace³, where pace is the time in seconds to cover one metre. For a 500m split of T seconds the pace is T/500 s/m, so watts = 2.80 / (T/500)³. A 2:00.0 (120s) 500m split therefore equals 2.80 / (0.24)³ ≈ 202.5 watts.
How are calories per hour figured on a Concept2 erg?
The Concept2 monitor uses Cal/hr = watts × 4 × 0.8604 + 300. The +300 term is a resting-metabolism offset, so the machine reports some calorie burn even at very low power. At 200 watts this gives roughly 200 × 4 × 0.8604 + 300 ≈ 988 Cal/hr.
Why does a slightly faster split cost so much more power?
Because power scales with the cube of pace. Rowing resistance rises roughly with the square of handle speed, and power is force times speed, so effort grows with speed cubed. Going from a 2:00 split (about 202 W) to a 1:45 split (about 302 W) is only 15 seconds but needs about 50% more power.
Do these calorie numbers depend on my body weight?
No. The Concept2 Cal/hr formula is based purely on the power you generate at the flywheel, not on your body mass, so two rowers holding the same split see the same calorie rate on the monitor. Your true metabolic burn does vary with body size and efficiency, so treat the monitor figure as a consistent training metric rather than an exact physiological measurement.
Does the drag factor change these results?
No. Drag factor changes how the resistance feels and how far the flywheel coasts between strokes, but the monitor measures the actual work done on the flywheel, so the watts-to-pace formula holds at any legal drag setting. Pick a drag that suits your stroke; the power for a given split is the same.

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