What Is FTP in Cycling and How Do I Improve It? UK Guide 2026

Last updated: June 2026

The Short Answer

FTP stands for Functional Threshold Power. It's the highest average power, in watts, that you can sustain for around an hour of riding. It's the most useful single number in cycling — it sets your training zones, predicts your race performance, and tracks your fitness over time. To improve it, you do specific structured workouts that target the threshold zone, ride consistently, and recover properly. There's no shortcut.

What FTP Actually Means

FTP is the dividing line between two physiological states. Below FTP, your body can clear lactic acid as fast as you produce it — you're in steady state, you can sustain the effort. Above FTP, lactic acid builds up faster than you can clear it, and you're racing a clock until your legs and lungs give out.

The exact figure (call it 250 watts for example) isn't the interesting bit. What matters is that FTP correlates strongly with how fast you can ride a 25-mile time trial, how well you can sustain a sportive pace, how long you can stay with a fast group ride, and how much absolute power you have to throw at any cycling task. Two riders with the same FTP will perform similarly in most cycling scenarios, regardless of body type, training history, or anything else.

FTP vs Watts per Kilo

Raw FTP is useful, but for hilly riding what matters is FTP divided by your body weight in kilograms — your watts per kilo (W/kg). A 90 kg rider with an FTP of 270W (3.0 W/kg) and a 60 kg rider with an FTP of 180W (3.0 W/kg) will climb at roughly the same speed. The lighter rider just produces less raw power because they need less to move themselves.

Zwift races and most categorisation systems use W/kg as their primary metric. Raw FTP matters more for flat riding and time trialling where weight is less of a factor.

What's a "Good" FTP?

Wattage figures are very personal — height, weight, training age, and genetics all matter. Rough W/kg benchmarks for the average male amateur cyclist:

For women, the figures shift down by roughly 0.3–0.5 W/kg at each level due to physiological differences in lean muscle mass.

Don't fixate on the absolute number. The number that matters most is your own — and whether it's higher this month than it was three months ago.

How to Test Your FTP

There are three common test protocols. All should be done after a warm-up of at least 15 minutes including some short hard efforts.

1. The 20-Minute Test (Classic)

Ride as hard as you can sustain for 20 minutes. Take your average power for those 20 minutes and multiply by 0.95. That's your FTP estimate. Brutal but accurate. Best done indoors on a steady gradient or smart trainer to avoid pacing variations.

2. The Ramp Test (Smart Trainer)

Used by Zwift and TrainerRoad. The trainer ramps the power up by a set amount (usually 20W) every minute until you can't continue. Take your final minute's average power and multiply by 0.75. Quicker than the 20-minute test (12–15 minutes total), less psychologically draining, but slightly less accurate for some rider types.

3. The 8-Minute Test

Two 8-minute all-out efforts with a 10-minute rest between. Take the average of both and multiply by 0.9. Used by Sufferfest/Wahoo SYSTM in their 4DP profile. More demanding than the Ramp Test, less so than the 20-minute test.

Should You Test Indoors or Outdoors?

Indoors. Always, if possible. A smart trainer eliminates wind, traffic, gradient changes, and pacing errors. Your indoor FTP will be a couple of percent lower than outdoor measurements (because indoor riding is harder due to heat and lack of recovery), but it's the more reliable benchmark to track over time.

How Often Should You Test?

Every 6–8 weeks during a structured training block. More often and you don't give yourself time to make meaningful gains. Less often and you're training off stale numbers.

How to Actually Improve Your FTP

The training principle is simple: to raise your threshold, you need to spend time training at and around it. There are three workout types that move FTP most reliably.

1. Sweet Spot Training (88–93% of FTP)

The bread and butter of FTP improvement. Sweet spot is hard enough to drive adaptation but easy enough that you can sustain large volumes of it. Typical session: 3 × 15 minutes at 90% of FTP, with 5 minutes recovery between. Do this twice a week and your FTP will climb.

2. Threshold Intervals (95–105% of FTP)

Direct work at FTP. Harder, lower volume per session. Typical session: 4 × 8 minutes at 100% of FTP with 4 minutes recovery. Demanding, effective, but you can only do these once or twice a week.

3. VO2 Max Intervals (110–120% of FTP)

Short, very hard efforts that raise your aerobic ceiling — which pulls FTP up over time. Typical session: 6 × 3 minutes at 115% of FTP with 3 minutes recovery. Brutal but high-yield.

The 80/20 Rule

The most well-supported training distribution: 80% of your weekly riding time should be easy (Zone 2, well below FTP), 20% should be hard (sweet spot, threshold, VO2). Riders who do too much in the middle ("grey zone" — too hard to be easy, too easy to drive adaptation) plateau fastest.

A Sample Week to Improve FTP

This is roughly 7–10 hours per week. Adjust volume to your available time, but keep the structure: one sweet spot day, one VO2 day, one long ride, the rest easy.

Common FTP Improvement Mistakes

1. Doing all rides at moderate intensity. The grey zone. You'll plateau within weeks. Push the easy rides easier, push the hard rides harder.
2. Skipping recovery. Adaptation happens during recovery, not during training. No rest days = no improvement.
3. Testing too often. Testing every two weeks shows noise, not progress. Test every 6–8 weeks.
4. Setting FTP too high. Workouts then become unsustainable, you fail them, and you lose the training stimulus. If a workout feels impossible, your FTP estimate is probably too high.
5. Setting FTP too low. Workouts then feel too easy and drive minimal adaptation.
6. Ignoring nutrition. Hard training without enough fuel doesn't make you faster — it makes you tired and ill.
7. Comparing your numbers to other people. The only relevant comparison is your FTP today vs your FTP six weeks ago.

How Much Can You Realistically Improve?

Honest figures for what's achievable:

• Brand new to structured training: 15–25% in the first 12 months
• Returning rider with previous training history: 8–15% in 6 months
• Experienced rider with consistent training: 3–5% per year
• Elite-level rider: 1–2% per year, if any

If you're new and you train consistently for 12 months with proper structure, an FTP gain of 30–50 watts is realistic. After that, gains slow significantly.

Indoor vs Outdoor FTP

Your FTP measured indoors will typically be 5–10 watts lower than the same effort measured outdoors with a power meter. This is normal — heat stress and lack of recovery during indoor riding mean the same physiological threshold produces a slightly lower power figure.

Use indoor FTP for your indoor training, and outdoor FTP (if you have a power meter) for your outdoor training. They're both valid; they're just slightly different baselines.

FAQ

Do I need a smart trainer to test my FTP?

No, but it makes the test much more accurate. A power meter on a road bike works fine outdoors if you have a quiet, steady stretch of road. Without either, FTP testing is unreliable.

Can I improve my FTP without structured training?

You can improve it somewhat by just riding more, especially if you're new. But to get serious gains, you need structured intervals targeting the right zones.

What's the difference between FTP and threshold heart rate?

Heart rate measures input — how hard your heart is working. Power measures output — how much work you're actually doing. Power is more directly related to performance. Heart rate lags by 30–60 seconds, varies with caffeine, sleep, hydration, and temperature, and is therefore less reliable for setting training zones.

Should I focus on FTP or W/kg?

Depends on your riding. Hilly events and races: W/kg. Flat time trials and pure power events: raw FTP. Most riders should track both.

How long does it take to see FTP gains?

With consistent structured training, expect to see your first measurable gain (5–15 watts) after 6–8 weeks. Further gains continue but at a slowing pace.

Is the Ramp Test as accurate as the 20-minute test?

For most riders, yes. The Ramp Test slightly underestimates FTP for riders with high anaerobic capacity (sprint-type riders) and slightly overestimates for endurance specialists. The 20-minute test is more universally accurate but psychologically harder.

Why does my FTP drop when I take a break?

Detraining is real. Two weeks off and you'll lose 2–5%. A month off and you'll lose 8–15%. The good news: previously-trained fitness comes back faster than it was built the first time.

Next Steps

• Read our Best Indoor Cycling Apps UK guide — Zwift, TrainerRoad, and others all have built-in FTP tests
• See our How to Start Indoor Cycling guide if you haven't yet set up your indoor training
• Browse our Best Smart Turbo Trainers UK 2026 if you don't yet have a power-measuring trainer

This article is general training information, not personalised coaching. For specific health conditions or competitive performance goals, consult a qualified cycling coach.

Shop the gear mentioned in this guide

• Wahoo KICKR CORE 2
• Bryton Smart Heart Rate Belt
• Bryton S500E GPS Cycle Computer

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