Instrument 05
Cycling FTP Calculator: Threshold Power, FTP Chart and FTP by Age
One test, converted to threshold power, placed on the chart, and adjusted for the years.
A cycling FTP calculator turns a test you can actually complete into threshold power, in watts and in watts per kilogram, which is the number training plans are written around. Nobody rides a true one-hour maximal effort to find it, so a shorter test is scaled instead by a convention, not a measurement.
Cycling FTP calculator: your threshold power
Functional threshold power
0 W · 0 W/kg
The cycling FTP chart, read by ability, not by watts
An FTP chart is only useful in watts per kilogram, because that is the figure that survives a change of rider. The bands below describe threshold power at roughly an hour. They overlap at the edges, and a rider near a boundary should read the nearer two bands together instead of picking one.
| Level | Men | Women |
|---|---|---|
| Novice | below 2.5 | below 2.1 |
| Recreational | 2.5 – 3.1 | 2.1 – 2.6 |
| Cat 4 | 3.1 – 3.7 | 2.6 – 3.1 |
| Cat 3 | 3.7 – 4.3 | 3.1 – 3.6 |
| Cat 2 | 4.3 – 5.0 | 3.6 – 4.2 |
| Cat 1 | 5.0 – 5.7 | 4.2 – 4.8 |
| Elite / professional | above 5.7 | above 4.8 |
Cycling FTP by age, and what the decline actually looks like
Cycling FTP by age holds up remarkably well into the mid-thirties, then falls by something between half a percent and one percent a year. The decline is gentle enough that a rider who starts training at forty will improve for years, because training gains comfortably outrun the age-related loss at that stage of life.
The figures below describe typical cycling FTP by age for a trained but not elite rider. Read them as a centre of gravity, not a target. Within any age band the spread between a sedentary rider and a consistent one is far wider than the gap between adjacent decades on this table.
| Age | Men W/kg | Women W/kg |
|---|---|---|
| 20 – 29 | 3.6 – 4.4 | 3.0 – 3.7 |
| 30 – 39 | 3.5 – 4.3 | 2.9 – 3.6 |
| 40 – 49 | 3.2 – 4.0 | 2.7 – 3.3 |
| 50 – 59 | 2.9 – 3.6 | 2.4 – 3.0 |
| 60 – 69 | 2.5 – 3.2 | 2.1 – 2.6 |
| 70+ | 2.1 – 2.7 | 1.7 – 2.2 |
Why the conversion factor matters more than the test
The twenty-minute protocol multiplies by 0.95 because a twenty-minute maximal effort sits a little above one-hour power for most riders. How far above varies with physiology: a rider built for short efforts will overshoot, and a diesel will undershoot, by several percent in either direction.
A ramp test scales peak minute power by about 0.75, and it is more sensitive still to individual differences. Both conventions are useful because they are repeatable, not because they are accurate. Use the same one every time and compare yourself against yourself, which is the only comparison that holds.
That is also the honest limit of any cycling FTP calculator, including this one. It reports what the convention says your test implies about threshold power. A meter reading three percent high moves every figure on this page by three percent, and no cycling FTP calculator can detect that from the outside.
Cycling FTP questions
What does the cycling FTP calculator actually compute?
It converts a test result into an estimate of the power you could hold for roughly an hour. A twenty-minute test is multiplied by 0.95, a ramp test by 0.75 of peak minute power. Those two coefficients are the conventional ones, and both are approximations, not measurements of anything.
Is a good cycling FTP an absolute number or watts per kg?
Watts per kilogram, for almost every purpose that matters on a bicycle. Three hundred watts is strong for a sixty-kilogram climber and ordinary for a ninety-kilogram rouleur. The absolute figure only decides flat and sheltered efforts, where frontal area matters more than mass does.
How much does cycling FTP fall with age?
Threshold power tends to decline by roughly half a percent to one percent a year once a rider passes the mid-thirties, and the curve steepens later. Training history moves that far more than birth year does: a consistent sixty-year-old routinely outperforms an untrained thirty-year-old by a wide margin.
Why does the FTP chart use category bands, not exact numbers?
Because the underlying data is a distribution, not a threshold. Riders in one racing category span a wide range of relative power, and the bands overlap considerably at their edges. A band tells you where you sit; a single number would imply a precision the measurement does not support.
How often is it worth retesting?
Every six to eight weeks during structured training, and rarely otherwise. Testing more often measures your freshness on the day rather than any change in fitness, and testing less often means training zones drift out of date. Repeat the same protocol each time or the comparison means nothing.
Related: the watts per kg calculator for a single effort rather than a threshold, the plausibility check when no meter was involved, and estimated against measured power on how far a calculated figure can drift from a meter.