2k Erg Calculator and Predictor

Split by distance: Paul's Law curves

Average /500m split against distance for four 2k times. Each doubling of distance moves the line 5 seconds. Enter a piece above and your own result lands on the chart; above the curve for your 2k means endurance to build, below it means speed.

One hard piece tells you what your 2k should be. Enter a time you have actually rowed at any distance and the predictor gives your 2k with the average split, the watts and the 500 m checkpoints, then every other distance from 500 m to the marathon. It runs two models side by side, Paul's Law and Riegel, because where they disagree tells you whether speed or endurance is holding your 2k back.

Paul's Law

Paul's Law is the rowing-native rule, credited to coach Paul Smith: each time you double the distance, your average /500m split slows by about 5 seconds, and each time you halve it, the split speeds up by 5. A 7:00 2k is a 1:45 split. Double to 4k and the rule says 1:50; a 5k is a bit more than double, so 1:51.6 and 18:36 total. Halve to 1k and it says 1:40, halve again to 500 m and 1:35.

The rule describes a rower with balanced speed and endurance, which is why it doubles as a diagnostic. If your real 500 m is faster than the law predicts from your 2k, speed is your strength and the aerobic side is the gap. If your 6k is faster than it predicts, you have the engine and the 2k is being left on the table by pacing or top-end power.

Riegel

Riegel is the running race model applied to the erg: predicted time = known time x (new distance / known distance) to the power 1.06. It agrees with Paul's Law almost exactly from 2k to 6k (7:00 gives 18:29 versus 18:36 for a 5k) and runs a little faster on the short end (1:37 for 500 m versus 1:35, and 6:31 versus 6:40 when predicting a 2k from a 1:30 500 m). Neither model knows about your pacing, your technique or the fact that a marathon needs fuel, so treat long-distance predictions as a ceiling.

The race plan

The predicted 2k comes with even-split checkpoints: the clock at 500, 1000 and 1500 metres if you hold the average exactly. Nobody rows dead even. The usual pattern is a second or two under the target in the first 500, settle onto the target through the middle thousand, and empty the tank in the last 500. A start that is 5 seconds fast is the most common way a 2k is lost; the checkpoints are there so you can see it at 500 m instead of at 1500. The 2k pacing guide covers the whole execution.

What is a good 2k erg time?

The honest reference is the Concept2 world rankings, which are split by sex, age and weight class. As broad bands most coaches would recognise: for men, 8:00 and slower is a normal starting point, 7:00 to 7:30 is fit and consistent, 6:30 to 7:00 is club-competitive and under 6:10 is the collegiate elite range. For women, 9:00 and slower is a normal start, 8:00 to 8:30 is fit, 7:30 to 8:00 is club-competitive and under 7:00 is elite. Lightweights, masters and juniors have their own standards, and a 40-something masters rower should read a decade-adjusted table, not the open one. The weight-adjusted calculator makes the heavy-versus-light comparison fair.

Which piece to use

The closer the test to 2k, the better the prediction. A recent 1k or 5k predicts a 2k tightly; a 500 m sprint says more about power than fitness, and a half marathon says more about patience. Use a piece from the last four to six weeks, on the same machine and drag factor you will race on. When you have two tests at different distances, enter both and compare: the 2k that both agree on is the one to plan for.

For the split-to-watts conversion in either direction, use the erg calculator. To put the 2k inside a training week that also has running and lifting in it, read the hybrid athlete training guide.

Paul's Law table: equivalent erg times

Find your 2k in the first column and read across for what the same fitness pulls at every other distance, or find a time you have actually rowed in any column and read back to the 2k it implies. Paul's Law adds 5 seconds to the /500m split for every doubling of distance and takes 5 off for every halving.

Half = 21,097 m. Marathon rows also carry drift from fueling and pacing that no formula sees.

Riegel table: the same times with the running model

Riegel scales time by the distance ratio to the power 1.06. It is a little more optimistic than Paul's Law on the short end and near identical from 2k to 6k. Where the two tables disagree for you is information: faster than Paul's Law at 500 m means speed is your strength; slower at 6k means endurance is the gap.

Riegel exponent 1.06, the value used for trained endurance athletes.

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