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Rowing Split Calculator

Converts an indoor-rowing distance and time (or a 500 m split) into the split per 500 m, pace per km, speed, power in watts using Concept2's watts = 2.80 / pace³ and the Performance Monitor's calorie rate, weight-adjusted when body weight is given.

When to use

You want the split, watts or calories for an erg piece, need to convert a target split into watts (or a wattage into a split) or want the finish time for a distance at a given split.

Do not use when: You are rowing on water (boat speed depends on hull and crew, and no watts are displayed) or you need running or swimming pace (use running-pace or swim-pace).

Formula

split_s = time_s × 500 / distance_m (or time_s = split_s × distance_m / 500); pace = split_s / 500 (s/m); watts = 2.80 / pace³; speed = 500 / split_s; calories_per_hour = 4 × watts × 0.8604 + 300 (monitor, 175 lb rower) or 4 × watts × 0.8604 + 1.714 × weight_lb (weight-adjusted); calories = calories_per_hour × time_s / 3600

watts = 2.80/pace³ and the weight correction (true kcal/h = monitor kcal/h − 300 + 1.714 × weight in lb) are Concept2's published formulas. The monitor's rate itself follows from 25 % mechanical efficiency (× 4) and 1 W = 0.8604 kcal/h (3600/4184) plus a 300 kcal/h base for a 79.5 kg rower; it is an estimate, not a measurement.

Inputs

ParameterTypeUnitRequiredDescription
distance_mnumbermnoDistance rowed in metres (e.g. 2000). Give it with time, or with split_per_500m to get the finish time. Range: > 0, ≤ 1000000
timestringnoElapsed time for distance_m as h:mm:ss, mm:ss (8:00) or plain minutes.
split_per_500mstringnoPace per 500 m as m:ss or m:ss.s (2:00.5); used when distance_m and time are not both given.
weight_kgnumberkgnoOptional rower weight for the weight-adjusted calorie rate (the monitor assumes 79.5 kg / 175 lb). Range: > 0, ≤ 300

Outputs

OutputTypeUnitDescription
split_per_500mstringm:ss.s/500 mTime per 500 metres, as shown on the monitor.
split_seconds_per_500mnumbers/500 mSame split as a number of seconds.
wattsnumberWConcept2: watts = 2.80 / (split_seconds / 500)³.
pace_per_kmstringmin:sec/kmTime per kilometre (2 × split).
speed_m_per_snumberm/s500 / split_seconds.
speed_kmhnumberkm/hSame speed in km/h.
calories_per_hournumberkcal/hPerformance Monitor rate 4 × watts × 0.8604 + 300, with 300 replaced by 1.714 × weight_lb when weight_kg is given.
timestringh:mm:ssElapsed time for distance_m (given or computed from the split).
distance_mnumbermDistance of the piece, when given.
calories_kcalnumberkcalcalories_per_hour × time / 3600 (only when the duration is known).

Example

2000 m in 8:00: {"distance_m":2000,"time":"8:00"} → {"split_per_500m":"2:00.0","split_seconds_per_500m":120,"watts":202.5,"pace_per_km":"4:00","speed_m_per_s":4.167,"speed_kmh":15,"calories_per_hour":997,"time":"0:08:00","calories_kcal":133}

2:30 split, 90 kg rower: {"split_per_500m":"2:30","weight_kg":90} → {"split_seconds_per_500m":150,"watts":103.7,"pace_per_km":"5:00","speed_kmh":12,"calories_per_hour":697}

GET https://tttkmbb.com/api/v1/calculate/rowing-split?distance_m=2000&time=8%3A00

Machine access

Sources

FAQ

How do I convert watts back to a split?

split_seconds = 500 × (2.80 / watts)^(1/3). For example 200 W gives 120.5 s, a 2:00.5 split.

Why does halving the split not double the watts?

Power rises with the cube of speed: going from 2:00 to 1:50 (9 % faster) needs about 30 % more watts (202 → 263 W).

Are the calories accurate?

They are the monitor's estimate for a 79.5 kg rower; with weight_kg the base rate is scaled by weight. Individual efficiency varies, so treat ±15 % as normal.

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