Critical Power (CP) Calculator
Informational calculator for rowing logs and planning. Build CP and W Prime estimates from test efforts and review model-based pace projections.
Critical Power Inputs
Enter two or three efforts from your recent rowing log.
Calculation Method
Test 1 (Short Effort)
Test 2 (Medium Effort)
3-minute max
3:00 - ~750-900m
7-minute max
7:00 - ~1800-2100m
12-minute max
12:00 - ~3000-3500m
Critical Power Estimate
263W
Split at CP: 01:50.0/500m
W Prime Estimate
Model work reserve
FTP Proxy
0.95 x CP estimate
Split at CP
/500m
Power-Duration Curve
The hyperbola shows predicted sustainable power at each duration. Your test points are overlaid.
Above-CP Time Estimates
Estimated finite duration for selected powers above CP:
Planning Power Ranges
Simple CP-based ranges for session logging and planning notes:
Race Pace Projections (Model-Based)
Projection solver combines the Concept2 pace-power conversion with your CP + W Prime estimate.
1,000m
1k
2,000m
2k
5,000m
5k
6,000m
6k
10,000m
10k
21,097m
Half Marathon
Critical Power Planning Notes
This page is designed for training logs and planning. It calculates CP and W Prime estimates from your entered efforts and provides model-based pace projections across common rowing distances.
Model Formula
CP is the slope of work vs. time, and W Prime is the intercept. These values are estimates from the inputs you provide.
Projection Logic
For each target distance, the calculator solves for time where required rowing power equals modeled power:
Confidence labels are based on target-to-input distance ratio: High (0.5x to 2x), Medium (0.25x to 4x), Low (outside that range).
FAQ
How often should I update entries?
Many users update every 4-8 weeks or after a clear change in recent session results.
Can I use race pieces instead of dedicated tests?
Yes. Recent hard efforts from your log can be used, as long as durations are distinct enough for the model fit.
Why are there confidence labels?
Confidence drops as projections move farther from your input distance range.
Is FTP a direct measurement here?
No. The FTP value is shown as a proxy estimate using 0.95 x CP.
References
- Monod H, Scherrer J. (1965). The Work Capacity of a Synergic Muscular Group.
- Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. (2016). Critical Power.
- Clark IE, et al. (2021). Critical Power and the power-duration relationship in endurance performance.
- Discussion of practical time limits around CP in validation contexts.
- Concept2 pace-power conversion reference.
Using CP and W'
CP is ideal for pacing strategy: any effort above CP depletes W' at a predictable rate. For a 2K race, knowing your CP and W' tells you exactly how much "above threshold" effort you can afford. CP is similar to FTP but derived from a mathematical model rather than a single-duration test, making it potentially more robust.
Model details: Methodology.
Related Tools
- FTP Calculator — alternative threshold estimation
- Power Curve — visualize your full power-duration profile
- Split Predictor — predict race times from CP data
Standards & Guides
- 2000m Rowing Standards — benchmark your 2K performance
- 5000m Rowing Standards — endurance benchmarks by age
- Training Zones Explained — apply CP to structured training