You're loggin in

Critical Power Calculator

Use two maximal efforts to estimate your Critical Power (CP), W′ capacity, and full power-duration curve using the two-parameter Critical Power model.

1

Power unit

The calculation is based on watts. If your power data is recorded in kilowatts, you can switch the input unit below.

2

Two maximal efforts

Enter two maximal efforts with different durations. For each test, use the highest average power you were able to sustain for that duration.

Effort 1

sec
W
Example: average power from a 3-minute maximal effort.

Effort 2

sec
W
The second effort must have a different duration from the first.
Work 1 —
Work 2 —
Status Waiting for data
The model: P = CP + W′ / t.
The calculator solves CP and W′ directly from the two measured efforts, then uses them to construct the power-duration curve.
3

Check your data

The two durations must be different. For a meaningful positive CP and W′ estimate, the longer effort should have the lower average power.

Important: with only two efforts, the model fits those two observations exactly. Therefore, an independent goodness-of-fit statistic such as R² cannot be meaningfully estimated from these two points alone.
✓ Free trial for new members  •  ✓ Nutrition & training in one place  •  🔒 Simple calorie tracking
Try the app for free

‍

How does the Critical Power Calculator work?

The Critical Power (CP) model describes the relationship between power output and the duration for which that power can be sustained. The two-parameter model estimates Critical Power and W′, the finite work-capacity parameter available above CP.

Metric Formula Meaning
Critical Power (CP) CP = (P₁t₁ − P₂t₂) / (t₁ − t₂) The power asymptote of the model, expressed in watts.
W′ W′ = P₁t₁ − CP × t₁ The finite work-capacity parameter available above CP, expressed in joules.
Power-duration relationship P(t) = CP + W′ / t The model's estimated power output for a given duration.

1. Two maximal efforts

Enter average power from two maximal efforts with different durations. The calculator uses seconds internally so that W′ is calculated in joules.

2. Solve CP and W′

The two measured points provide the two observations required to solve directly for the two model parameters.

3. Build the power-duration curve

The resulting CP and W′ values are then used to estimate theoretical power at multiple durations.

Two-parameter Critical Power model:
P = CP + W′ / t

P is power in watts, CP is Critical Power in watts, W′ is the finite work-capacity parameter in joules, and t is duration in seconds. The model can also be expressed using total work: Work = CP × t + W′.

With two efforts, the model necessarily fits the two input points exactly. Therefore, an independent goodness-of-fit statistic or R² value cannot be estimated from those two points alone. Using additional trials allows regression-based assessment of model fit and residual error.

The calculator displays W′ in kJ for readability while performing the underlying calculation in joules. The model is primarily a framework for describing the power-duration relationship during severe-intensity exercise.

GetFIT App
GetFIT App wrote this article
wrote this
Fitness Calculators
Critical Power Calculator (CP)

The Critical Power Calculator estimates Critical Power (CP) and W′ from two maximal efforts with different durations. It uses the established two-parameter model P = CP + W′ / t to solve the two model parameters directly from the two measurements. It then uses those values to generate a modeled power-duration curve across multiple durations.

Medical Disclaimer: The calculator results and information provided in this article are for educational and informational purposes only and do not constitute medical, health, or professional advice. Always consult with a qualified healthcare provider before making any decisions related to your health, diet, or fitness goals. Individual results may vary, and this tool should not be used to diagnose or treat any medical condition.

What is Critical Power and what does the CP value mean?

Critical Power is one of the two parameters in the classic two-parameter power-duration model. It represents the power asymptote of the model as exercise duration becomes longer. The calculator estimates CP in watts from two maximal efforts with different durations.

#1

Results

Calorie Tracking

Our app helps you track your daily calories and nutrients with high accuracy. Just a few clicks and you’re done.

Try for free!
More Meal Plans

How does the calculator calculate Critical Power?

The calculator uses the two-parameter relationship P = CP + W′ / t. With two measured power-duration points, the two unknown parameters can be solved directly without requiring a regression package. The test durations must be different, and a meaningful positive solution requires the longer effort to have a lower average power.

#1

Results

Recipes for Fat Loss

Our app gives you high-protein fitness recipes that make losing weight and making progress easy every day!

Try for free!

What is W′ and what does it represent?

W′ is the second parameter in the two-parameter Critical Power model and represents a finite work-capacity parameter available above CP. It is measured in joules, which is why the calculator displays the result in the more practical unit of kilojoules. W′ should not simply be treated as an “anaerobic energy store,” because its physiological interpretation is more complex.

#1

Results

High Protein Meals

You’ll never feel hungry on your diet again if you eat the high-protein fitness recipes in our app!

Try for free!

How does the Critical Power power-duration curve work?

The calculator uses P(t) = CP + W′ / t to estimate power at different durations. As duration increases, the W′/t component becomes smaller, so the modeled power progressively approaches CP. This mathematical relationship creates the characteristic hyperbolic power-duration curve of the two-parameter model.

#1

Results

Simple Calorie Tracking

With our app’s precise calorie tracking and food diary, hitting a calorie deficit has never been easier.

Try for free!

Are two tests enough to estimate Critical Power?

Two tests are mathematically sufficient to solve for the two unknown parameters, CP and W′. However, two points always produce an exact fit, meaning there is no independent goodness-of-fit statistic or R² value that can meaningfully evaluate the model from those two points alone. Additional trials allow regression-based assessment of model fit and residual error.

#1

Results

High Protein Diets for You

Our easy-to-make, high-protein recipes help you hit your ideal daily protein intake effortlessly!

Try for free!

What can the Critical Power model be used for?

The Critical Power model provides a sports-science framework for examining the relationship between sustainable power output and exercise duration. It can be useful for performance profiling, training analysis and monitoring changes in the modeled power-duration relationship. The resulting CP and W′ values remain model estimates and depend on the quality and protocol of the maximal efforts used to generate them.

#1

Results

Workout Plans for Your Goals

Our app offers a wide range of workout plans!

Try for free!

GetFIT App: Not Just a Calorie Counter — Your Complete Online Body Transformation Membership for Weight Loss & Muscle Building

Why pay for separate programs, apps and courses for calorie tracking, workouts, and meal plans? GetFIT App is an all-in-one web app membership that gives you everything in one place, fully online. Set up your account in seconds and reach your goals faster, with less hassle.

Feature GetFIT App 🌟 Other Calorie Tracker
Apps
Calorie Tracking Yes Yes
AI Powered Meal Analysis Yes No
Intermittent Fasting Log Yes No
Workout Tracking Yes No
Hundreds of High-Protein Recipes Yes No
4-Week Meal Plans Yes No
4-Week Workout Plans Yes No
Body Weight Tracking Yes No
Water Intake Tracking Yes No
Body Measurement Tracking Yes No
Knowledge Library & E-books Yes No
Progress Tracking Yes No
Seasonal Winter/Fall Diet Recipes Yes No
Step Count & Daily Habit Tracking Yes No
International Recipe Library Yes No
Diet Shopping Lists Yes No
Supplement Programs Yes No
Easy-to-Use Online Platform Yes No
Try the App for Free
Free Trial for new users
Cancel Anytime
Thousands of Users Worldwide
Secure Payment

Who Is GetFIT App For?

If you've ever gotten stuck losing weight, had no idea how many calories or how much protein you actually need, or you're just tired of bland, boring diet food — you're not alone. GetFIT App was built for people who want to finally reach their weight loss or muscle-building goals in one place, with a clear system and food they actually enjoy eating. Look through the situations below, and if you recognize yourself, you'll know exactly what to do next.

You have no idea how many calories to eat Weight loss, muscle building, and maintenance all need different targets — the app calculates exactly how many calories and how much protein your goals require. Try the app! You don't know how to put together a workout plan You show up at the gym but have no idea what to do or in what order? Ready-made, easy-to-follow 4-week workout plans get you started. Try the app! You're tired of bland, boring diet food Who said dieting means dry chicken breast and rice? Choose from hundreds of delicious, high-protein recipes you'll actually want to eat. Try the app! The scale hasn't moved in weeks Stuck on a weight-loss plateau and not sure what's going wrong? Clear tracking and logging help you spot exactly what needs adjusting. Try the app! You're a beginner and don't know where to start Everyone feels lost at the start, with so much conflicting information out there. You get a simple, step-by-step system, no guesswork required. Try the app! You can't hit enough protein every day You know you should, but the numbers never add up? The app helps you plan meals so you actually reach your daily protein target. Try the app! You want a simple, effective plan you can actually follow Whether it's weight loss or muscle building, one clear, day-to-day plan beats ten scattered pieces of advice — and you get it all in one place. Try the app! You don't have time to sit and calculate everything Just describe what you ate, and the AI works out the calories and macros for you in seconds. Try the app! You want to keep progressing without setbacks Consistent tracking and clear goals help you avoid losing weeks of progress or losing your momentum. Try the app! You've tried crash diets before, but they never stuck This isn't another quick fix — it's a sustainable system you can actually build into your everyday life. Try the app! You want to finally hit your goal weight Whether it's a few pounds or something bigger, a clear plan and daily tracking make a real difference in actually getting there. Try the app! You want to look better, feel fitter, and feel more confident As your body changes, your confidence often grows with it — consistent training and nutrition can help with both. Try the app! You want to build muscle effectively A training plan, enough protein, and recovery — you need all three for muscle growth, and you'll find them all in one place. Try the app! You want to lose weight without starving yourself or yo-yo dieting Starving yourself isn't the answer — a sustainable calorie and protein intake is something you can actually stick with long-term. Try the app! You want to build a healthier, fitter lifestyle It's not about one diet — it's about small, sustainable habits around food, movement, and routine that you can keep up long-term. Try the app! You want to finally reach the physique you've always wanted The shape you've always pictured feels a lot more realistic with a clear plan and a consistent daily system behind it. Try the app!
Try the App for Free
Free trial for new members
Cancel anytime
Thousands of members worldwide
Secure payment

GetFIT App Is Not a "Magic Pill" — It's a System That Supports You and Gets You to Your Goal!

GetFIT App helps you so you don't have to figure out how to reach your goals on your own. In one place, you'll find everything you need for a mindful lifestyle change: calorie and macro tracking, daily calorie logging, 4-week workout plans, delicious and easy-to-follow recipes, and progress tracking. You won't get quick tricks — you'll get a clear, transparent system that helps you move toward your goal more consistently, whether that's weight loss, muscle building, or a fitter, more sustainable lifestyle.

Fast, Simple Calorie & Macro Tracking

You describe what you ate, and GetFIT App calculates the calories and macros in seconds — no more digging around or doing math in your head. You'll also see exactly how many calories you have left for the day.

Workout Plans & Workout Logging

Effective 4-week workout plans are ready to go, and your workout log helps you stay consistent and track how you progress from session to session.

High-Protein Recipes & Ready-Made Meal Plans

Hundreds of delicious recipes and 4-week meal plans are waiting for you, so you don't have to figure out what to eat every single day.

Body Weight, Measurements & Daily Habit Tracking

All your important numbers in one place, so you can see exactly whether progress is actually happening — not just feel it, but see it.

Progress Tracking

Clear data and charts help you know exactly where you stand, and what's worth adjusting in the weeks ahead.

Knowledge Resources & a Supportive System

You don't just get tools — you get knowledge too, so you understand why you're doing what you're doing, for the long run.

Try the App for Free
Free trial, new members only
Cancel anytime
Thousands of members worldwide
Secure payment

GetFIT App Will Be Perfect for You, If...

If you relate to any of the statements below, GetFIT App is exactly the right fit for you.

Try the App for Free
Free trial, new members only
Cancel anytime
Thousands of members worldwide
Secure payment

Join Thousands of GetFIT App Users Worldwide

Thousands of people around the world have already joined GetFIT App to track their nutrition, follow workout programs, and work toward their fitness goals. Join our growing global community and get the tools you need to manage your fitness journey in one place.

Start your Free Trial!

Everything You Need for a Fitter Body is here in GetFIT App!

Set calorie and macro goals, track your meals and activity, follow structured workout and meal plans, and monitor your progress over time. GetFIT App brings nutrition tracking, fitness planning, and everyday tools together in one simple membership.

Start your Free Trial!

Try GetFIT App for 5 days free!

Discover the premium features of the GetFIT App during a free trial: personalized calorie calculation and tracking, meal plans, recipes, workout programs, e-books, and much more. Start your transformation today!

Start Free Trial

Dear User! Unlock your Dream Body Today!

Start your free trial today! With your premium membership, you’ll get immediate access to all the tools and content that help you lose weight, build muscle, and develop a healthy lifestyle.

Click to Get Started