Cycling FTP Calculator
The formula
Why 95% of a 20-minute power
Andrew Coggan defined functional threshold power as the highest power a cyclist can sustain for approximately one hour, which is miserable to measure directly — a maximal 60-minute effort is hard to pace and hard to motivate yourself through. The 20-minute test is the practical proxy: maximal aerobic power declines roughly log-linearly with duration, and empirical data showed the average cyclist holding a 20-minute all-out effort settles at about 95% of their hour power. The factor is a population average, not a personal constant — sprinters with a large anaerobic reserve can lose more than 5% going from 20 minutes to 60, while pure endurance riders sometimes lose less than 3%, which is why coaches cross-check FTP against race data and heart-rate decoupling.
Zones are tools, not cages
The seven-zone model maps onto physiology only loosely below zone 4. Zones 1–3 are governed by fatigue accumulation and are best treated as broad intensity bands: rides at 65% FTP lasting three hours and rides at 88% FTP lasting ninety minutes train different things, and neither is precisely "tempo". Zones 4 and 5 straddle threshold, where small errors produce big differences in recovery cost, so a 5-W miscalibration can turn a sustainable sweet-spot session into a supra-threshold effort you cannot repeat twice a week. The most robust habit is to keep 75–85% of your riding genuinely below 75% FTP, and reserve the hard bands for two or three focused sessions.
W/kg, and why absolute power still matters
Power-to-weight predicts climbing speed almost perfectly, which is why it dominates cycling culture: 3.5 W/kg gets you dropped on local hills, 4.5 W/kg makes you competitive in a cat 1 race, and Grand Tour climbers average above 6 W/kg on high mountains for hours. But flat racing and time trialling are governed by absolute watts against aerodynamic drag, which scales with the cube of speed — a 90 kg rider at 300 W (3.33 W/kg) will usually beat a 60 kg rider at 240 W (4.0 W/kg) on a calm, flat course. Judge your numbers by what you are training for, and compare re-tests against the same bodyweight you tested at, not the leanest you have ever been.
Frequently asked questions
What is a good FTP for a cyclist?
How should I take a 20-minute test?
How often should I retest?
My power meter disagrees with my trainer — which FTP is right?
Source & methodology
Coggan AP & Allen H, Training and Racing with a Power Meter (zones and the 95% rule); Hunter I, Martin J & Bateman A, Journal of Sports Science and Medicine 2004 (20-min vs 60-min CT validation); MonLacticPower / Coggan power profiles for category-level W/kg benchmarks.
Cycling FTP: what this tool answers
This page was written for one job: turning your own inputs into a defensible figure, with the working shown. There are plenty of pages about Cycling FTP; almost none of them show the working. This one does: the formula, every input, a fully computed example, and a sensitivity analysis calculated live from this engine’s own defaults.
What makes Cycling FTP worth calculating is not precision but position: it tells you which side of a threshold you are on, and by how much. A rough figure that settles the direction beats an elaborate one that never commits.
Most confusion about Cycling FTP comes from mixing up the input you control with the input you merely observe. The formula treats them identically, but your decisions should not: one deserves measurement, the other deserves a defensible estimate.
Every figure in the prose is generated by the engine rather than written beside it — the worked example resolves to functional threshold power = 238 watts on the default inputs, and the sensitivity section ranks the inputs that move the result — Best 20-minute average power first, at ≈10.0 % of the headline for a ten-percent error either way in that input. Read the sections in order and you will be able to reproduce every figure by hand.
Inside the Cycling FTP calculation: formula and every input
One formula, published in full: FTP = 20-min mean power × 0.95 · zones = % of FTP (Z1 150) · W/kg = FTP ÷ body mass. Anything you can read, you can reproduce in a spreadsheet, and that reproducibility is the whole point of printing it rather than hiding it behind a button.
Best 20-minute average power (watts) (example value 250) is a measured number in the unit named by the label; the formula does not convert for you. Replace the example with the figure from your own records — the tool recomputes instantly and the printed steps follow your numbers.
Rider weight (lb) (example value 165) is a measured number in the unit named by the label; the formula does not convert for you. Weigh rather than estimate where you can — this field usually enters the formula multiplicatively.
Rider weight (kg) (example value 75) is a quantity rather than a category — precision here is cheap and worth having. Use the same conditions each time (same scale, same time of day) so that changes in the output reflect real change.
Test duration used (example value 20 minutes — standard test (×0.95)) is a categorical input — the option you choose decides which numbers the formula uses. Be precise about the boundary (exact date, start of month); time inputs decide the exponent in most formulas.
5-minute best power (watts, optional) (example value 340) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. This input feeds the formula directly; a defensible figure here is worth more than false precision anywhere else.
What each “Test duration used” choice actually does: 20 minutes — standard test (×0.95) → 238 watts · 60 minutes — 30-min TT protocol (×0.75) → 188 watts · 8 minutes — ramp-style estimate (×1.15) → 288 watts · 6 minutes — short effort (×1.30) → 325 watts That table is the honest answer to “does this option matter”, re-derived from the formula rather than hard-coded into page copy.
The default Cycling FTP calculation, written out in full
The tool prints its own working; this is the same arithmetic on the example values, reproduced so you can follow it by hand. Starting figures: Best 20-minute average power (watts), Rider weight (lb), Rider weight (kg), Test duration used. Run to the end, the functional threshold power resolves to 238 watts — 250 W × 0.95 from a 20-min effort · 3.17 W/kg on the bands this tool uses.
- FTP = 250 W × 0.95 = 238 watts — the 5% deduction covers the fact that a 20-minute effort is slightly shorter than a true one-hour maximal steady state.
- Power-to-weight = 238 ÷ 74.8 kg = 3.17 W/kg, placing you in the Cat 3 band on Coggan-type tables.
- Zone 2 = 56–75% of FTP = 133–178 W; zone 4 = 91–105% = 216–249 W.
- Sweet spot (88–94%) = 209–223 W — high training stress with manageable fatigue.
- Estimated flat speed scales with the cube root of power: 38 km/h at 250 W × (238/250)^⅓ × (74.8/75)^⅓ = 37.3 km/h.
- Anaerobic reserve = 340 − 238 = 103 W of power above threshold — a large gap means sprint/burst fitness, a small one a pure-diesel profile.
Power-to-weight ratio — 3.17 W/kg. Read next to the headline, this is the figure that shows the shape of the trade-off.
Zone 2 ceiling (endurance) — 178 watts. If your inputs change, this is usually the first companion figure to move.
Sweet spot range — 216 watts. If your inputs change, this is usually the first companion figure to move.
Zone 4 top (threshold) — 249 watts. Read next to the headline, this is the figure that shows the shape of the trade-off.
Zone 5 range top (VO₂max) — 285 watts. Compare it against the main result of 238 watts before drawing conclusions.
Keep this worked example open while you enter your own figures: matching the shape of the substitution is the fastest way to spot a unit or convention mistake.
Scenario table: Cycling FTP at ±10 % and ±20 % of the key input
The honest version of any estimate is a corridor, and this one is cheap to produce: Cycling FTP was recomputed at 5 points along the dominant input, with every other field left untouched.
| Best 20-minute average power setting | Functional threshold power |
|---|---|
| 80 % of the example value | 190 watts |
| 90 % of the example value | 214 watts |
| example inputs | 238 watts |
| 110 % of the example value | 261 watts |
| 120 % of the example value | 285 watts |
Across 5 settings of Best 20-minute average power, the result spans 190 watts to 285 watts. A decision that only works at one row of this table is a decision waiting for an input to move. Reproduce it in the form above by editing Best 20-minute average power alone; the substitution steps will follow your figures exactly.
What actually moves your Cycling FTP
This list was computed for this specific engine just now: each numeric input was nudged ±10 % while every other field held its example value, and the functional threshold power was recalculated from scratch. It is the fastest honest answer to “what matters most in Cycling FTP?” — and it is specific to these defaults, because sensitivity moves with the starting point.
- Nudge Best 20-minute average power by ±10 % and Cycling FTP lands between 214 watts and 261 watts (sensitivity ≈10.0 %)
Best 20-minute average power is the dominant lever here: ten percent either way moves the result by about 10.0 %, from 214 watts to 261 watts. Spend your verification effort there first. The remaining fields can sit at safe defaults without materially changing the answer — knowing which is which is what separates a careful calculation from an anxious one.
Is your Cycling FTP good — reading the result bands
Nobody acts on a bare figure — they act on a figure with a comparison attached. The verdict attached to the default calculation — “250 W × 0.95 from a 20-min effort · 3.17 W/kg” — is one band on a ladder your own figure may sit somewhere else on. The sensitivity list shows how far a modest input error moves you along that ladder: for Best 20-minute average power, ±10 % covers 214 watts to 261 watts. The practical reading rules: read the band as a starting hypothesis, then test it: change the two dominant inputs by ten percent and see whether the verdict survives. Verdicts that survive stress are the ones worth acting on.
Related measures answer related questions, and the distinctions matter: Cycling FTP is the quantity, Functional threshold power is this tool’s reading of it, and the decision that follows belongs to neither of them separately.
How people get Cycling FTP wrong
Power-to-weight predicts climbing speed almost perfectly, which is why it dominates cycling culture: 3.5 W/kg gets you dropped on local hills, 4.5 W/kg makes you competitive in a cat 1 race, and Grand Tour climbers average above 6 W/kg on high mountains for hours. But flat racing and time trialling are governed by absolute watts against aerodynamic drag, which scales with the cube of speed — a 90 kg rider at 300 W (3.33 W/kg) will usually beat a 60 kg rider at 240 W (4.0 W/kg) on a calm, flat course. Judge your numbers by what you are training for, and compare re-tests against the same bodyweight you tested at, not the leanest you have ever been.
Treating the example inputs as a recommendation. They are a demonstration of the mechanism — a decision-grade Cycling FTP begins the moment your own figures replace them.
One mistake is specific to this engine: assuming every input matters equally. The computation above shows Best 20-minute average power dominating — a careful figure there beats false precision everywhere else.
The subtlest error is answering the wrong question precisely. Confirm that functional threshold power is actually the quantity your decision needs — the arithmetic is flawless either way, which is what makes the mistake invisible.
Before you trust your Cycling FTP: a short checklist
- Compare the result with one independent method or published benchmark.
- Verify each input against its original source document, not memory.
- Put Best 20-minute average power under a magnifier; the sensitivity table above is the reason why.
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- Record the date and the inputs alongside the number so future-you knows what was assumed.
- Confirm the answer against one independent method or published benchmark for Cycling FTP.
Step by step: getting a trustworthy Cycling FTP out of this tool
The tool does the arithmetic; the routine below is what makes the arithmetic trustworthy. Five steps, a minute total — and afterwards you will know not just what the number is, but which assumption produced it.
Step 1 — start from evidence. The inputs behind Cycling FTP are best 20-minute average power (watts), rider weight (lb), rider weight (kg), test duration used, 5-minute best power (watts, optional). Write them down with their source next to each one; if you cannot name where a figure came from, that is the input most likely to be wrong. When two sources disagree, it is almost never the arithmetic that differs.
Step 2 — compute the version you would not be embarrassed by. If a stranger audited your inputs, which set would you hand over? Enter that set, read the result, and treat everything else as upside. If the verdict changes with a ten-percent nudge, report the nudge alongside the number.
Step 3 — change one input at a time. Nudge a single field by ten percent, watch the headline and its companions move, then undo it. Two or three fields will dominate — the sensitivity table above already ranks them for this engine. The test of a good estimate is not that it feels right but that it changes what you do.
Step 4 — run the scenario trio. Expected, pessimistic, optimistic. The gap between pessimistic and expected is the number to plan against; the optimistic result is useful only as a ceiling. If the verdict changes with a ten-percent nudge, report the nudge alongside the number.
Step 5 — schedule the next run. In Health & Medical the inputs drift quietly. Put a reminder a quarter out, re-enter the same fields, and read the change rather than the level. When in doubt, prefer the boring input: the interesting one is usually the one you misread.
From calculation to decision: where Cycling FTP earns its keep
In Fitness Performance the figure computed here is usually the first one somebody asks to see. Having it — with the formula behind it — changes your position in the conversation from participant to reference. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
Used properly this is a five-minute filter that saves weeks. Compute Cycling FTP, reject what fails, and only then bring in the expensive analysis for the survivors. Re-running a number costs seconds; retracting a decision costs considerably more.
Nothing here is stored or transmitted, so the habit of checking is free: open the page, re-enter current figures, compare with the number you saved last time. Write the assumptions in the same file as the result, and future arguments take minutes instead of meetings.
Quick answers: what searchers ask about Cycling FTP
What affects Cycling FTP the most?
Cycling FTP is driven above all by Best 20-minute average power. Perturbing only that field by ten percent either way produced 261 watts against the 238 watts baseline — a ≈10.0 % response.
How much does the “Test duration used” choice change the answer?
Across every option this tool offers, the functional threshold power ranges from 188 watts (60 minutes — 30-min TT protocol (×0.75)) to 325 watts (6 minutes — short effort (×1.30)) with all other inputs held at their example values. The per-option table is printed in the inputs section — this is a decision that genuinely moves the number, not a cosmetic dropdown.
What is a typical Cycling FTP?
On the worked example above Cycling FTP comes out at 238 watts. Treat that as one point on a distribution rather than a norm: the bands, the companion outputs and the sensitivity ranking tell you how wide the plausible range really is.
How do I calculate Cycling FTP by hand?
Three steps: write the formula (FTP = 20-min mean power × 0.95 · zones = % of FTP (Z1 150) · W/kg = FTP ÷ body mass), insert your values, and simplify. The worked example section shows exactly that chain for the default inputs; replicating it once on paper teaches you more about Cycling FTP than any number of calculator runs.
What happens to Cycling FTP if best 20-minute average power changes by 10 %?
The engine was re-run with that field moved by ten percent while everything else stayed fixed: the functional threshold power goes across 214 watts to 261 watts, a swing of roughly 10.0 % around the 238 watts baseline. That ratio is the practical definition of how much this input matters.
Is the Cycling FTP result of 238 watts good or bad?
Neither, on its own — the label “250 W × 0.95 from a 20-min effort · 3.17 W/kg” is the band this figure falls in for the example inputs, and your own inputs will place you elsewhere on the same ladder. Judge the number against your history and your alternatives, and remember that a ten-percent error in Best 20-minute average power alone moves it by ≈10.0 %.
Does Cycling FTP change with age?
Yes — reference bands shift deliberately across the lifespan, which is why this tool prints an interpretation rather than a bare number. Re-read the bands each time inputs like Best 20-minute average power (watts) change materially.
How often should I check Cycling FTP?
Whenever an input changes by more than a few percent, and otherwise on the rhythm of your decisions — before a purchase, a review, a renewal. Cycling FTP is a snapshot, not a subscription; stale snapshots are the most common silent error in Health & Medical planning.
What is a good FTP for a cyclist?
Untrained men commonly sit near 2.0–2.5 W/kg and untrained women near 1.6–2.0; regular club riders reach 3.0–4.0 W/kg, cat 1 racers 4.2–4.8, and WorldTour professionals 5.5–6.5 W/kg on a climbing day. Absolute FTP of 250 W is a common milestone for a fit amateur male rider.
How should I take a 20-minute test?
Warm up for 15–20 minutes with two or three one-minute bursts, then ride 20 minutes as evenly as possible — start 1–2% below target rather than banking time with a fast opening. Give a minute or two of easy spinning beforehand if you need it, and do the same test conditions (indoor trainer, road, wind) each time so results compare.
Does this Cycling FTP tool store my numbers?
No. The entire calculation runs in your browser session; nothing entered above is transmitted or saved, which is the correct behaviour for sensitive Health & Medical figures and the reason you can re-run this page as often as you like.
Glossary for Cycling FTP
- Power-to-weight ratio
- 3.17 W/kg on the example inputs — a companion figure printed beside the headline of Cycling FTP so that no result is read in isolation.
- Zone 2 ceiling (endurance)
- 178 watts for the Cycling FTP worked case; it sits next to the main result because it carries context the headline leaves out.
- Sweet spot range
- 216 watts for the Cycling FTP worked case; it sits next to the main result because it carries context the headline leaves out.
- Functional threshold power
- The primary output of this tool: 238 watts for the default inputs, computed exactly from FTP = 20-min mean power × 0.95 · zones = % of FTP (Z1 150) · W/kg = FTP ÷ body mass.
- Worked example
- The step-by-step substitution printed above, so the arithmetic can be re-derived by hand or in a spreadsheet.
- Verdict band
- A named zone on the range of plausible results; the example inputs land in “250 W × 0.95 from a 20-min effort · 3.17 W/kg”, and your inputs may not.
- Sensitivity (±10 %)
- How far the Cycling FTP moves when a single input is nudged ten percent either way; the ranked list on this page is computed live from this engine.
Where the Cycling FTP model comes from
Everything above runs on one stated formula, applied without hidden coefficients: FTP = 20-min mean power × 0.95 · zones = % of FTP (Z1 150) · W/kg = FTP ÷ body mass. Source of record: Coggan AP & Allen H, Training and Racing with a Power Meter (zones and the 95% rule); Hunter I, Martin J & Bateman A, Journal of Sports Science and Medicine 2004 (20-min vs 60-min CT validation); MonLacticPower / Coggan power profiles for category-level W/kg benchmarks. Specialist software layers extra coefficients on top of the same algebra; none are hidden here, and that transparency is what makes a disagreement traceable to a specific input instead of a black box.
Nothing here replaces a qualified professional, and nothing here is approximate either — the arithmetic is exact, and the honesty is in the inputs you supply. The design constraint was set by usefulness rather than by comfort: an estimate you can interrogate beats an answer you have to trust.
Turning this Cycling FTP into a decision
Save the number together with its inputs and today’s date; a Cycling FTP figure without context is unusable the moment an input changes.
This page was written for people who need one trustworthy number before their next decision, and the promise is that nothing above required trust. Bookmark the tool, re-run it whenever an input moves by more than a few percent, and keep the date with the number.