What formula does this predictor use?

It uses the rowing power-pace relationship, often called Paul's Law, which states that pace per 500 metres changes by about one second for each doubling or halving of distance. Mathematically the time scales with distance raised to an exponent near 1.06, capturing how pace slows over longer pieces.

How accurate is a 2K prediction from another distance?

Predictions are most accurate when the test piece is close to 2K and is a genuine maximal effort. A 5K or 6K predicts a 2K reasonably well; very short sprints or very long steady-state pieces are less reliable because they rely on different energy systems.

What is the confidence range for?

The range shows a realistic spread around the point estimate because the scaling exponent varies between athletes and pacing affects results. Treat the middle figure as your target and the range as the band most well-paced races fall into.

Does this work for both rowing and the erg?

The scaling rule was derived from Concept2 erg data and is most reliable there. On-water rowing adds wind, stream, boat, and rigging variables, so use the erg estimate as a guide and expect more variation on the water.

Why does pace slow down over longer distances?

Over longer pieces you must hold a lower power output to avoid blowing up, because aerobic capacity and fatigue limit sustainable output. The power-law exponent above one encodes this: doubling distance costs you a few seconds per 500 metres of pace.

Rowing 2K Time Predictor

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This tool predicts your 2000 m rowing erg time from any other maximal test piece using the well-established power-pace relationship in rowing, sometimes called Paul’s Law. Enter a 5K, 6K, 1K or any timed distance, and it scales the result to an equivalent 2K with a confidence range.

How it works

Rowing pace and distance follow a power law. If t1 is your time over distance d1, the predicted time t2 over distance d2 is:

t2 = t1 × (d2 / d1) ^ k

The exponent k is about 1.06 for rowing — slightly above 1, which is why pace per 500 m slows as distance grows. This is equivalent to Paul Smith’s rule of thumb that your 500 m split changes by roughly one second per doubling or halving of distance. The predicted 2K is then converted to a 500 m split:

split per 500 m = predicted 2K time / 4

A confidence range is shown by evaluating the formula at exponents of 1.04 and 1.08 to reflect athlete-to-athlete variation.

Example and tips

A 6000 m piece rowed in 24:00 predicts a 2K of about 24:00 × (2000 / 6000) ^ 1.06 ≈ 7:34, a 500 m split near 1:53. For the most reliable prediction, test with a distance within a factor of three of 2K and row it as a true maximal effort with even pacing. Sprints under 1K and long steady pieces over 10K push the formula outside its reliable range, so use those only as rough guides.