Health & Fitness
Cycling Interval & W′ Balance Calculator
Updated Aug 27, 2026 Reviewed Aug 27, 2026
Build repeated intervals and simulate second-by-second W′ depletion above critical power and adjustable recovery below it.
Critical-power interval model
Build work and recovery sets
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Live W′ balance preview
Work spends capacity; recovery restores it
Minimum W′ balance
1.9 kJ
Ending balance
88%
Session duration
41:00
The stepped power pattern is compared with a transparent exponential W′ recovery model.
How to use this calculator
- 1Enter established CP, W′ and recovery τ.
- 2Set warm-up and cool-down, then add repeated work/recovery sets.
- 3Inspect minimum, ending balance and depletion time.
Formula
W′bal -= (P − CP)Δt above CP; exponential recovery below CP
A one-second reservoir model keeps its recovery assumption visible.
Calculation steps
- Start at full W′.
- Step through all phases once per second.
- Record balance, work and time above CP.
Worked example
Four 3-minute efforts at 330 W can be modeled against 280 W CP and 20 kJ W′.
Assumptions
- CP and W′ are separately established.
- Recovery is an approximation.
- Recovery occurs between repetitions only.
- Zero balance is a model flag.
Sources
Frequently asked questions
Where do CP and W′ come from?
Use suitable maximal efforts and the critical-power calculator.
What does τ do?
Larger τ means slower modeled recovery.
Is W′ a battery?
No; the reservoir is a useful abstraction.
Why can another tool differ?
Implementations use different recovery equations and parameters.
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