How accurate are 2k erg predictions from longer tests?

Predictions from 5k and 6k tests are typically accurate within 4-8 seconds for most athletes. Predictions from 10k and 30-minute tests are typically accurate within 6-12 seconds because the gap to 2k pace is larger. Heavyweight rowers tend to over-predict 2k from longer tests because they hold pace better at distance. Lightweights tend to under-predict for the same reason. The calculator above shows three confidence-banded estimates so you can pick the band most representative of your physiology.

Why does the calculator give three different times?

Most physiology lies on a spectrum. The "best case" estimate uses a Riegel exponent of 1.05 - typical for sprinters or athletes with strong anaerobic systems. The "likely" estimate uses 1.06 - the population-average exponent across endurance sports. The "cautious" estimate uses 1.07 - typical for athletes with weaker anaerobic systems or heavy training fatigue. Pick the estimate closest to how you usually feel between distances - if you fade hard from 6k to 2k, lean cautious; if you can sprint at the end of long pieces, lean best.

What is a sensible 2k pacing strategy?

Most successful 2k strategies use either an even split or a slight negative split. Even split means 500m, 1000m, 1500m and 2000m all hit the same projected pace. Negative split means starting 1-2 seconds slower than target and finishing 1-2 seconds faster. Fly-and-die (going out 5+ seconds under target) is rarely successful at IRA, Sprints, or Stotesbury level - it bleeds time disproportionately in the 1k-1500m segment. The calculator above generates a target split for each 500m at each predicted time, so you can pick the strategy that fits your race plan.

Should I use a 5k, 6k, 10k or 30min test for prediction?

5k is the most predictive for 2k because the metabolic systems overlap more. 6k is the standard test in NCAA collegiate programs and most prep school crews, so it's the most commonly available data point for varsity selection. 10k and 30min predictions need more interpretation because they sit deeper in aerobic territory. If you have results from multiple test distances, run the calculator on each and average. Programs that test consistently across 2k, 5k and 6k usually settle on a personal Riegel exponent within a season - that's what coaches really mean by "knowing the athlete".

2k Erg Prediction Calculator: Predict Your 2k from 5k, 6k, 10k or 30min

Race-day pacing

2k Prediction Calculator

Predict your 2k from any longer test - 5k, 6k, 10k or 30 minutes. See three confidence bands and the 500m-by-500m race plan to hit each one. Used by NCAA varsity programs and prep school crews to set IRA, Sprints, and Stotesbury target times.

How do you predict a 2k erg score?

The standard method is the Riegel endurance model: T2 equals T1 multiplied by D2 over D1, raised to the fatigue exponent (1.06 for most athletes). Plug in a 5k, 6k, or 30-minute test and the formula predicts your 2k. Race-fit varsity rowers pull the exponent toward 1.04, while base-fit novices and walk-ons sit closer to 1.08.

Your test result

Test type

Time

: min : sec

Distance covered (meters)

Typical 30-minute distances: 7,000m (recreational), 8,000m (club), 8,800m (collegiate), 9,500m+ (elite varsity / national team).

Test summary

Predicted 2k (likely)

Best case

Cautious

500m race plan for each prediction

Even-split target (recommended for most athletes). Negative-split alternative below.

Prediction	Target time	500m	1000m	1500m	2000m

All quarters at the same average split. The first 500m typically goes 2-3 seconds quicker because of the start sequence; the last 500m typically goes 2-3 seconds quicker because of the sprint. The middle two splits are where the prediction lives or dies.

Negative-split alternative

Start 1.5 seconds slower than target average and finish 1.5 seconds faster. For your "likely" prediction of , that means:

Negative splits work best for athletes with strong anaerobic finishes. If you typically die in the third 500m, an even split is safer.

How the prediction works

The Riegel formula with three exponents

Pete Riegel's endurance formula T2 = T1 * (D2 / D1)^c converts a known time at one distance into a predicted time at another. The exponent c captures how fast a particular athlete fades as distance grows. The population-average value across endurance sports is 1.06, but individuals sit on a spectrum from roughly 1.04 (strong anaerobic finishers) to 1.08 (pure aerobic specialists). This calculator runs three exponents - 1.05 (best case), 1.06 (likely) and 1.07 (cautious) - and shows the resulting 2k for each.

Why predictions are not perfect

The Riegel model assumes the same physiology drives performance at both distances. For 2k, that's roughly 75-80% aerobic, 20-25% anaerobic. For 5k, it's 90% aerobic, 10% anaerobic. For 10k, it's 95% aerobic. As the gap between test and target distance grows, the prediction relies more heavily on extrapolating an anaerobic system you didn't actually test. That's why 2k predictions from 30-minute tests are typically less reliable than from 5k tests.

Pacing strategy decoded

Even split is the safest race plan and works for most varsity rowers. You hit the average target pace at 500m, 1000m, 1500m and 2000m. Negative split (starting slow, finishing fast) works for athletes with strong anaerobic systems and good pacing discipline. Fly-and-die (going out fast, holding on) is the most common novice mistake at IRA, Sprints, and Stotesbury - it bleeds time disproportionately in the 1000-1500m segment because lactate accumulation outpaces clearance. The calculator above shows the splits for each strategy at each predicted time.

Use this with the training pace calculator

Once you have a predicted 2k, plug it into the training pace calculator to see your UT2, UT1, AT, TR and AN paces. Use the rowing pace chart to see how the prediction sits across every distance. Use the erg score calculator to convert it to a weight-adjusted, age-graded percentile.

Predicting your 2k is one calculation. Selecting a varsity eight from squad predictions is twenty.

A head coach building a varsity eight wants 2k predictions for every athlete from their last 5k and 6k tests, weighted by how recent the test was, with confidence bands. That's exactly what Row HQ does inside coach tools, pulling lineups from current data via practice attendance tracking. Read the crew selection guide for how varsity coaches use erg data plus seat-racing to set lineups.

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