Pace, watts and predictions on the rowing machine

On the rowing machine the reference is the pace per 500 metres, the split: the number the monitor shows on every stroke. But the same effort can also be read in watts, which measure power and let you compare different people and pieces, and in watts per kilogram, which take body weight into account.

This calculator takes the distance and time of a piece and returns the pace per 500 m, average power, watts per kg and estimated calories per hour. Using Paul's law, it also estimates pace and time over another distance, for example your 5,000 m from a 2,000 m.

How the calculation works

• Pace per 500 m: time divided by distance, multiplied by 500.
• Watts: 2.80 divided by the cube of the pace in seconds per metre, the formula used by Concept2 monitors.
• Calories: 4 times the watts plus 300 kcal per hour, the Concept2 estimate for an average person.
• Paul's law: each time the distance doubles, the pace slows by about 5 seconds per 500 m.

The verdict is based on watts per kilogram, which make people of different builds comparable.

From pace to watts

Power grows with the cube of speed: going a little faster takes much more power.

Going from 2:00 to 1:50 per 500 m means about 30% more power: that is why each second gained on your pace costs more and more effort.

Paul's law: predicting another distance

Paul's law is a rule of thumb from indoor rowing: each time the distance doubles, the average pace slows by about 5 seconds per 500 m. Starting from a 2,000 m at a 2:00 pace:

The rule works best between nearby distances and for people trained at both: those who train mostly over long distances tend to slow less, those who do mostly short pieces slow more.

The four bands of the verdict

• Below 2 W/kg: a starting level, with plenty of room to improve.
• 2 to 3 W/kg: a level typical of regular recreational training.
• 3 to 4 W/kg: a trained-athlete level.
• 4 W/kg and above: a competitive level.

The bands are indicative and apply mainly to pieces of a few minutes, such as the 2,000 m. Short pieces inflate watts, very long ones lower them.

How much body weight matters

On the rowing machine body weight is not lifted against gravity as on a climb, so heavier people start with an advantage in absolute watts. Watts per kilogram partly correct for this. At 75 kg, here are the pace and 2,000 m time matching each threshold:

How to use your pace in training

Many programmes set sessions from the 2,000 m pace: for example long easy work 15-20 seconds slower, threshold work 8-12 seconds slower and short intervals close to or faster than 2,000 m pace. Knowing your pace lets you dose the effort instead of going by feel.

Limits of the calculator

The watts formula is the one used by Concept2 rowers and applies to machines calibrated the same way; other models may give different values. Calories are an estimate for an average person and do not account for weight, age or individual efficiency. Paul's law is a rule of thumb: use the result as a reference, not as an exact prediction.

Frequently asked questions

How do you calculate the 500 m split on a rower?

Divide the time by the distance and multiply by 500. A 2,000 m in 8:00 corresponds to a 2:00 pace per 500 m.

How do you convert pace to watts?

With the Concept2 formula: watts = 2.80 divided by the cube of the pace in seconds per metre. A 2:00 pace per 500 m is about 203 W.

Why does going a little faster take so many more watts?

Because power grows with the cube of speed: going from 2:00 to 1:50 per 500 m takes about 30% more power.

What is Paul's law?

It is a rule of thumb: each time the distance doubles, the average pace slows by about 5 seconds per 500 m. It is used to estimate a time over a different distance.

How accurate is the Paul's law prediction?

It is a reference: it works best between nearby distances and for people trained at both. Those more suited to endurance tend to slow less.

What do watts per kg mean?

They are power divided by body weight and make people of different builds comparable. The calculator's bands are indicative and designed for pieces of a few minutes.

How many calories does rowing burn?

The Concept2 estimate is 4 times the watts plus 300 kcal per hour: at 150 W about 900 kcal/h. It is an estimate for an average person.

Why does the monitor show tenths after a point?

It is the rowing monitor convention: 1:45.3 means 1 minute, 45 seconds and 3 tenths. The calculator uses it for consistency.

Are short pieces reliable for the verdict?

Less so: short pieces produce more watts than pieces of a few minutes. The most reliable comparison is on pieces of at least 2,000 m.

Does the calculator apply to every rower?

The watts formula is the Concept2 one and applies to machines calibrated the same way; other rowers may give different values.

How do I use my 2,000 m pace in training?

Many programmes use the 2,000 m pace as a reference: easy work 15-20 seconds slower, threshold 8-12 seconds slower, short intervals close to 2,000 m pace.

Can I estimate a half-marathon time?

Yes, by entering 21,097 m as the target distance. Over such long distances the estimate is less certain and depends heavily on endurance training.