FTP / Power Zone Calculator

What FTP means in this calculator

Functional threshold power (FTP) is a cycling training reference used to set power-based workout ranges. This calculator offers two simple conversions: multiply a 20-minute average by 0.95, or multiply the best one-minute value from a ramp test by 0.75. It then applies preset percentages to produce seven power bands. If you enter body weight, it also divides the estimated watts by kilograms to show watts per kilogram. These are model outputs based on the test type selected, not laboratory measurements or universal definitions of threshold.

Different software, coaches, and testing protocols can use different ways to estimate threshold and divide zones. The calculator’s ramp-test coefficient is a rough conversion, not a substitute for the protocol used by your trainer or training platform. The 20-minute result also depends on pacing, warm-up, terrain or trainer setup, calibration, fatigue, and how the test was performed. A valid-looking number does not prove that the test was maximal, uninterrupted, or comparable with a previous result.

Prepare a test that produces interpretable data

Before testing, choose a safe environment with enough uninterrupted time and a bicycle or indoor trainer that is in working order. Follow the full warm-up and test procedure supplied by the platform, coach, or protocol you are using. Do not combine the one-minute value from one test format with the 20-minute option. Make sure the power meter or trainer is paired, calibrated according to its maker’s instructions, and recording the correct source. Note whether the test was indoors or outdoors, the position used, and the equipment involved.

A test is a demanding effort. It may be inappropriate during illness, injury, unexplained symptoms, or a period of unusual fatigue. If you have a medical condition or uncertainty about exertion, consult an appropriately qualified clinician before doing maximal testing. Choose a controlled setting rather than a public road with traffic, intersections, or descents. If the data drop out or the effort is interrupted, do not treat the displayed conversion as a clean baseline; repeat later under safe and comparable conditions.

Follow one conversion into the power zones

Suppose the 20-minute field contains an average of 200 watts. This calculator multiplies 200 by 0.95 and rounds the result to 190 W. It then calculates its bands from that estimate: Zone 1 up to 55% of the estimate, Zone 2 from 56–75%, Zone 3 from 76–90%, Zone 4 from 91–105%, Zone 5 from 106–120%, Zone 6 from 121–150%, and Zone 7 above 151%. The exact ranges can differ from a cycling platform that uses another model or boundary convention.

For the ramp option, entering a best one-minute result of 250 W produces 188 W after rounding the 0.75 conversion. That does not mean the two tests should produce equal estimates for every athlete. The page applies separate coefficients by design; the output is not a comparison of which protocol is more accurate for you. If a coach’s protocol tells you to use a different estimate, keep that method consistent rather than mixing the calculator’s bands into another system.

Understand watts per kilogram without turning it into a ranking

Watts per kilogram is a ratio: estimated FTP in watts divided by the weight entered in kilograms. It can help describe the relationship between power and body mass in some cycling contexts, particularly when climbing, but it does not describe all cycling ability. Aerodynamics, absolute power, course profile, duration, handling, fueling, pacing, and equipment also affect performance. A ratio should not be treated as a health target or a reason to change body weight. The tool does not assess body composition or prescribe weight change.

Check that weight is in kilograms rather than pounds. If you leave a default value or enter a value from a different date, the ratio will not describe your current setup. It can also change because of scale variation, not a real performance shift. Keep the raw test watts alongside the converted FTP so that a future comparison can distinguish measurement from arithmetic. Do not compare your result with another rider without matching test protocol, equipment, and context.

Apply the estimate within a complete training plan

Use the zones as a starting language for workouts that specify power targets. If an easy ride feels unexpectedly hard or a prescribed interval is not repeatable, review measurement quality, fatigue, terrain, and the session design before raising the threshold. A higher setting is not automatically better. Re-test after a suitable training period or when the current plan calls for it, not after every good ride. Follow the testing platform’s update process so the new reference does not silently change several workouts at once.

Compare the result with the heart-rate zone calculator only as a second measure; heart rate and power are different signals. The pace calculator uses race speed and pace assumptions rather than FTP. If a test is missed because of fatigue or schedule pressure, review the missed-workout adjuster before moving it into a harder week. For context on the common 20-minute conversion and its limitations, see this TrainingPeaks explanation of FTP testing. Keep the method, raw data, and date with your result.

When two tests or devices disagree

Do not average incompatible results just to get a compromise number. First check whether both used the same test protocol and recording source. A ramp result and a steady 20-minute result are produced by different efforts and converted with different assumptions. Power meters can also differ because of placement, calibration, firmware, temperature, zero offset, or recording dropout. If one value came from an indoor trainer and another from an outdoor meter, compare the raw files and device instructions before treating the gap as a fitness change.

Look for a pattern in workouts as well as test values. If every interval in a prescribed range is far too difficult or unusually easy across several sessions, review the setting with a coach or the platform’s guidance. A single poor workout can reflect sleep, stress, fueling, heat, or a bad day, so it does not automatically invalidate the threshold. Preserve both readings with their dates and context, then choose one consistent method for the next block. This record makes later comparisons more meaningful and avoids moving training targets in response to noise.