Cycling FTP Estimator from 20-Min Test

Functional Threshold Power (FTP) is the highest average power you can sustain for approximately one hour.
It is the cornerstone metric for structured cycling training because it anchors all your training zones to your actual physiology rather than to generic heart rate tables.

The 20-minute FTP test is the standard protocol.
You ride all-out for 20 minutes on a flat road or steady-state trainer, record your average power, and multiply by 0.95.
The 5% reduction accounts for the difference between a 20-minute maximal effort and a true 60-minute threshold effort.

FTP = average_20_min_power × 0.95

There are two other common test formats if you cannot do a 20-minute effort:

• 8-minute test: multiply average power by 0.90
• Ramp test: take the last 1-minute average and multiply by 0.75

Ramp tests (progressively increasing wattage every minute until failure) have become popular on indoor trainers because they are less mentally demanding and more repeatable.
They tend to slightly overestimate FTP for endurance-trained riders and slightly underestimate for strength-type riders, but they are good enough for zone calibration.

Coggan power zones were developed by Andrew Coggan and Chris Carmichael and have become the industry standard for cycling training.
Zone 2 (endurance) is where most training volume should live — conversational pace, fat-burning, building aerobic base.
Zone 4 (lactate threshold) is at or just below your FTP — the hardest sustainable effort.
Zone 5 and above are interval work for VO2max and sprint development.

Watts per kilogram (W/kg) is the key number for comparing riders regardless of body weight.
For reference, recreational cyclists typically test at 2-3 W/kg, Cat 3-4 racers at 3-4 W/kg, and professional road cyclists exceed 5-6 W/kg at race weight.