Example Data Table
| Rider |
FTP |
Weight |
W/kg |
Endurance Zone |
Threshold Zone |
| Base Builder |
220 W |
78 kg |
2.82 |
123-165 W |
200-231 W |
| Club Rider |
275 W |
72 kg |
3.82 |
154-206 W |
250-289 W |
| Climber |
310 W |
64 kg |
4.84 |
174-233 W |
282-326 W |
Formula Used
Direct FTP: Final FTP = Direct FTP × (1 + Adjustment Percent ÷ 100).
Test FTP: Final FTP = Test Average Power × Test Factor × (1 + Adjustment Percent ÷ 100).
Zone watts: Zone Limit = Final FTP × Zone Percent ÷ 100.
Power to weight: W/kg = Final FTP ÷ Rider Weight.
Mechanical work: kJ = Adjusted Target Watts × Minutes × 60 ÷ 1000.
Estimated calories: kcal = kJ ÷ Efficiency Decimal ÷ 4.184.
How To Use This Calculator
Choose direct FTP if you already know your current threshold value.
Choose field test mode if you want the calculator to estimate FTP from a recent power test.
Enter rider weight to calculate watts per kilogram.
Select a target zone and planned duration for ride planning.
Use readiness reduction when work stress, sleep, heat, or fatigue requires lower targets.
Press calculate to view the result above the form.
Use CSV or PDF export to save the report.
Understanding Cycling Power Zones
Power zones turn a single threshold number into useful training ranges. They help riders pace climbs, intervals, commutes, and long endurance work with less guesswork. A construction worker, site manager, or builder who rides for fitness can also use zones to balance hard labor with safe training stress.
Why FTP Matters
Functional Threshold Power, or FTP, is the estimated power you can hold for about one hour. It is not perfect, yet it gives a steady anchor for planning. The calculator accepts direct FTP values or test power from common field tests. It then applies a selected factor and any adjustment you choose.
Using Zones in Daily Training
Zone one is easy recovery. Zone two builds endurance. Zone three supports steady tempo work. Zone four targets threshold strength. Zone five develops oxygen capacity. Zone six trains short anaerobic power. Zone seven covers very hard sprints. These ranges should guide effort, not replace judgment.
Advanced Planning Benefits
The calculator also links power with body weight, duration, and expected energy demand. Watts per kilogram helps compare climbing ability. Estimated mechanical work shows how much work the ride may require. Metabolic calories are estimated from efficiency, so they remain a guide rather than a medical value.
Good Data Practices
Power meters can drift. Smart trainers can read differently. Outdoor wind, heat, surface, and traffic change real effort. Test under similar conditions when possible. Use the same bike setup when comparing results. Update FTP after a strong test, a training block, or a clear fitness change.
Interpreting the Result
Do not chase exact watts every second. Aim for smooth averages across intervals. Use lower zone limits on tired days. Use higher limits only when recovery is good. The readiness adjustment helps reduce targets when work stress, poor sleep, or heavy site activity has already raised fatigue.
Final Notes
Power zones are most useful when reviewed with notes, heart rate, cadence, and perceived effort. Exporting the result lets you keep records for coaching or personal planning. Over time, the trend matters more than one ride. Consistent tracking makes training clearer, safer, and easier to repeat. Small changes can protect recovery while still supporting steady progress through busy weeks and demanding jobs.
FAQs
What is FTP?
FTP means Functional Threshold Power. It estimates the highest average power a rider can sustain for about one hour. It is widely used to set cycling training zones.
Which FTP test should I use?
Use the test you can repeat consistently. A 20 minute test is common. Ramp tests are easier indoors. Consistency matters more than the exact protocol.
Why does the calculator include readiness reduction?
Readiness reduction lowers the target wattage for tired days. It helps account for poor sleep, heavy work, heat, stress, or soreness before a ride.
What is watts per kilogram?
Watts per kilogram compares power with rider weight. It is useful for climbing and performance tracking, especially when riders have different body weights.
Are these zones exact?
No. Zones are practical ranges. Power meters, fatigue, terrain, and weather can change real effort. Use heart rate and perceived effort with the result.
What is sweet spot power?
Sweet spot power is usually near 88 to 94 percent of FTP. It gives strong training value without the full stress of threshold work.
Why are calories only estimated?
Calories depend on rider efficiency, body size, conditions, and measurement accuracy. The calculator uses mechanical work and efficiency to create a useful estimate.
Can I export the result?
Yes. Use the CSV button for spreadsheet records. Use the PDF button for a simple printable report with FTP, targets, and zone ranges.