Key Takeaways
- Enter one 2K result and you get split, watts, watts per kilogram and a weight-adjusted time. Watts come from Concept2's own formula[4].
- VO2max is shown three ways, from Concept2[1], Klusiewicz and Faff[2] and Jensen et al.[3]. They disagree, and the gap is the real uncertainty.
- None of them measures VO2max. In one study the error of a 2K-based estimate was larger than the real change in VO2max over a training cycle[6].
- There is no "level for your age" rating. I explain why further down, and where to find one.
How the Calculator Works
Each piece has a published source.
| Result | How it is worked out | Basis |
|---|---|---|
| Split and watts | Split is the 2K time divided by four. watts = 2.80 / pace3, pace in seconds per metre | Concept2 Watts Calculator[4] |
| Watts per kilogram | Average watts divided by body weight in kg | Plain arithmetic |
| Weight-adjusted time | Time × (weight in lb / 270) to the power 0.222 | Concept2 Weight Adjustment Calculator[5] |
| VO2max, Concept2 | (Y × 1000) / body weight in kg, where Y comes from your 2K time in minutes, sex, weight and training level | Concept2 VO2max Calculator[1] |
| VO2max, Klusiewicz and Faff | Men: 1.682 + 0.0097 × watts. Women: 1.631 + 0.0088 × watts. Result in L/min | Biology of Sport, 2003[2] |
| VO2max, Jensen et al. | Men only: (10.96 × watts + 1168) / 1000, in L/min | Int J Sports Physiol Perform, 2021[3] |
What each result is and where it comes from. Source numbers match the sources list.
Worked example: 7:00 for 2000 m, 80 kg man
The split is 1:45.0, which is 302 W and 3.78 W/kg.
Not highly trained, Concept2 gives 55.0 mL/kg/min, Klusiewicz and Faff 57.7 and Jensen 56.0. Highly trained, Concept2 gives 65.0.
The weight-adjusted time is 6:22.1, from a factor of 0.9098.
Why There Are Three VO2max Numbers
Each equation was fitted to a different group of rowers.
Concept2's equation comes from Dr. Fritz Hagerman's lab VO2max tests, paired with the same people rowing a maximal 2000 m[1]. Concept2 says it assumes your training level is about the same as his subjects.
Klusiewicz and Faff tested 44 men and 27 women from a national team and its back-up squad[2]. Their equations use mean 2K power, and they report a total error of 4.9% in men and 4.95% in women.
Jensen and colleagues fitted theirs to 34 male club rowers aged 18 to 30, then checked it on 14 others[3]. On those 14 rowers the technical error was 3.6% and the validation r was .94. It was built on men only, so this page does not offer it for women.
For a 65 kg woman rowing 8:00, Concept2's not highly trained equation gives 43.4 and Klusiewicz and Faff give 52.5 mL/kg/min. That is a gap of 9.1 from one rowing time.
I do not know which of these is closest for you. I found no study that compares all three in the same rowers, so the page shows the range and leaves the choice to you.
Using It to Track Progress
A better 2K is a better sign than a changed estimate.
Concept2 says a faster 2K after good training is a good sign your rowing VO2max has improved, whichever estimator you use[1]. That advice is about your time, not about the decimal on the estimate.
A later study tested 8 women and 14 men twice, 5 months apart in the women and 7 in the men[6]. It used the Klusiewicz and Faff equations, including the 2K power one on this page.
The total error of its indirect methods was 4.2 to 7.7% in women and 5.1 to 7.4% in men. Measured VO2max rose 3.0% in the women and fell 4.3% in the men, so the error was bigger than the real change.
The authors called these methods of rather low use for tracking changes in trained rowers.
Concept2 says the untrained may improve VO2max by up to around 20% and the well trained perhaps 3 to 5%[1]. Watch your 2K time and your watts instead.
The Weight-Adjusted Time
Useful for comparing rowers, but it cannot be ranked.
A heavier rower can produce more power, which often means a better erg score. On the water, Concept2 says the extra body weight sinks the boat deeper and adds drag, and the erg does not penalise that. The adjustment tries to account for it[5].
Concept2 says the adjusted score is a good estimate of your potential speed in an eight, in good conditions, and that the adjusted score cannot be entered in the Online Ranking[5]. For a version with more distances, use the Erg Calculator.
What It Cannot Tell You
Worth knowing before you plan around the numbers.
- It is not a measurement. All three VO2max figures are regressions fitted to groups of rowers. Concept2 says VO2max is best measured in a lab[1].
- The 2K must be a true maximal effort. Concept2's equation is for a maximal 2000 m[1], and a badly paced or easy piece will understate the result.
- Damper setting. Use whichever damper setting gives you your best 2K, which is how Concept2 says its study was done[1]. The monitor already corrects power for the damper[5].
- Weight thresholds make the Concept2 figure jump. The highly trained equation changes at 61.36 kg for women and 75 kg for men, and Concept2 warns you may see confusing numbers there[1].
- Age. Concept2 says Hagerman did not have enough data in older age groups[1], and Jensen's group was aged 18 to 30[3]. Take the numbers more loosely outside those groups.
- Tool limits. The tool accepts a 2K time from 5:00 to 12:00 and a body weight of 40 to 180 kg. These are limits of this tool, not published rules.
Why There Is No Level for Your Age
The data I found is not mine to reuse.
Concept2's Online Ranking shows the 90th, 75th, 50th and 25th percentile times for each age group, sex and weight class[7]. That is the best reference I found for how a 2K compares.
Concept2's Logbook terms allow personal use of its content but not commercial use without written consent[8]. This site carries ads, so I did not copy those numbers into a table.
Open the ranking, pick your age group, sex and weight class, and compare your time there. Those people chose to log a ranked result, so they are not a cross-section of everyone who rows.
What I Removed From the Old Version
Numbers I could not trace to a source.
The old page used a VO2 formula, power × 10.8 divided by body weight plus 35. I could not find it in Concept2 or in the rowing studies above.
It also had a performance level table, age decline percentages, training zones, energy system shares by distance, a stroke rate table and an improvement timeline. I found no source for them, so they are gone.
Training zones now live in the Rowing FTP Calculator and the Erg Calculator, where each one cites its own sources.
Frequently Asked Questions
Sources & References
- VO2max Calculator for Indoor Rowing. Concept2. Concept2.com
- Indirect methods of estimating maximal oxygen uptake on the rowing ergometer. Klusiewicz A, Faff J. Biology of Sport 20(3):181-194 (2003)
- A Maximal Rowing Ergometer Protocol to Predict Maximal Oxygen Uptake. Jensen K, Frydkjaer M, Jensen NMB, Bannerholt LM, Gam S. International Journal of Sports Physiology and Performance 16:382-386 (2021)
- Watts Calculator (pace to watts and watts to pace). Concept2. Concept2.com
- Weight Adjustment Calculator. Concept2. Concept2.com
- Indirect Methods of Assessing Maximal Oxygen Uptake in Rowers: Practical Implications for Evaluating Physical Fitness in a Training Cycle. Klusiewicz A, Borkowski L, Sitkowski D, Burkhard-Jagodzińska K, Szczepańska B, Ładyga M. Journal of Human Kinetics 50:187-194 (2016)
- Using the Online Ranking as a Training Tool. Concept2. Concept2.com blog, 17 April 2023
- Logbook Terms and Conditions of Use (last modified 19 December 2016). Concept2. log.concept2.com
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Disclaimer: This calculator is for informational and personal journaling purposes only. It logs measurements and compares them to published reference values. It is not health, medical, or nutrition advice.