How To Measure Ftp 20 Min 8 Min And Ramp Tests?

Functional threshold power (FTP) is the highest power you can hold for about an hour. You can estimate it with a 20-minute test, an 8-minute test, or a ramp test. Each one uses a math step to turn a shorter, harder effort into an FTP number.

The three tests differ in how long you ride and how you pace. The 20-minute test is the most widely used. The 8-minute test is shorter but easier to get wrong. The ramp test is the easiest to pace but tends to run high for some riders.

What Is FTP And Why Does The Test Method Matter?

FTP is a training anchor, not a lab measurement. It stands for the power you could theoretically sustain for roughly 60 minutes before fatigue forces you to slow down.

Your body produces energy through two main systems. Below a certain intensity, you can clear lactate about as fast as you make it, so you can keep going for a long time. Above that intensity, lactate builds up faster than you can clear it, and you fade. FTP is meant to sit near that line.

Because a true one-hour effort is brutal and hard to repeat, most tests use a shorter effort and a correction factor. That is where the 20-minute, 8-minute, and ramp tests come in. Each one trades accuracy for practicality in a different way.

One clarification worth knowing: FTP is an estimate no matter which test you use. Two riders with the same fitness can get different numbers from different protocols. The goal is consistency, not a perfect number.

How Do You Do The 20-Minute FTP Test?

This is the most established method. It comes from work by exercise physiologist Andrew Coggan, who proposed subtracting 5% from your best 20-minute average power to estimate FTP.

The protocol usually looks like this:

• Warm up for 10 to 20 minutes, building gradually.
• Do a few short, hard efforts to open up your legs.
• Recover for several minutes of easy spinning.
• Ride a hard, steady 20-minute effort at the highest power you can hold evenly.
• Cool down.

Then take your average power for the 20 minutes and multiply it by 0.95. So if you averaged 250 watts, your estimated FTP is about 238 watts.

The hard part is pacing. Go out too fast and you blow up in the last five minutes. Go out too easy and you leave power on the table. Most riders do best starting slightly below what feels sustainable and lifting the effort in the final five minutes.

This test works because 20 minutes is close enough to an hour that the math correction is small. It is also long enough that pacing errors tend to even out.

How Do You Do The 8-Minute FTP Test?

The 8-minute test follows the same idea but uses two shorter efforts instead of one. The common version, popularized by the training platform TrainerRoad, has you ride two 8-minute efforts as hard as you can hold, then take 90% of the average of the two.

The structure is usually:

• Warm up thoroughly.
• Ride a first 8-minute effort at maximum sustainable power.
• Recover for about 10 minutes of easy spinning.
• Ride a second 8-minute effort, aiming to match or slightly beat the first.
• Average the two efforts and multiply by 0.90.

So if your two efforts averaged 270 watts, your estimated FTP is about 243 watts.

The 90% factor exists because an 8-minute effort sits well above threshold. You are drawing more on your short-term energy systems, so the number needs a bigger correction than the 20-minute test.

The trade-off is real. Eight minutes is short enough that a strong anaerobic push can inflate your result. Riders with a big sprint or a strong short-duration engine often test higher here than their true hour power. If your 8-minute number looks high compared to how you actually ride, that is a known weakness of the method.

How Do You Do A Ramp Test?

A ramp test is the simplest to execute. Instead of pacing a hard effort, you just pedal until you cannot anymore. The test does the pacing for you.

The typical protocol starts easy and increases power in set steps every minute. A common version starts around 100 watts and adds about 20 watts each minute. You keep going until your cadence drops and you cannot hold the target power.

Your FTP is then estimated from your best one-minute power during the test, multiplied by about 0.75. So if your best minute hit 320 watts, your estimated FTP is about 240 watts.

The appeal is that there is no pacing to get wrong. You cannot start too hard, because the resistance controls the effort. That makes it reliable to repeat, which matters more than many riders realize.

The downside is the same anaerobic issue as the 8-minute test, only more so. The ramp test leans heavily on your top-end power, and riders with strong short efforts often get a number that is too high for steady riding. Riders with a strong aerobic base but modest top-end power sometimes get a number that is too low.

How Do The Three Tests Compare?

None of these is a true measurement of hour power. They are estimates built on assumptions about how your body responds to shorter efforts. The assumptions hold better for some riders than others.

If you have access to a longer effort, a genuine 40 to 60 minute hard ride gives you the most direct estimate. Most riders do not want to do that often, which is exactly why the shorter tests exist.

Which FTP Test Should You Use?

Pick one test and stick with it. That single habit matters more than which protocol you choose, because your training zones are built from the number you produce.

If you are new to testing, the 20-minute test is a solid default. It has the longest track record and the smallest correction factor, which means less room for the math to drift from reality.

If pacing a 20-minute effort feels impossible, the ramp test removes that problem. Just expect the number to run a little high if you have a strong short-duration engine. Many coaches suggest lowering a ramp result slightly for riders who know their top-end power flatters the estimate.

The 8-minute test sits in the middle. It is shorter than the 20-minute test but still requires you to pace two hard efforts. It works well for riders who find a single long effort mentally draining.

A few practical points apply to all three:

• Test when rested. A hard training week will drag your number down.
• Use the same equipment and setup each time.
• Retest every four to six weeks, or when your fitness clearly changes.
• Treat the number as a guide, not a verdict.

One thing worth saying plainly: a higher FTP number is not proof of better fitness on its own. It only means something when paired with how you actually perform on the road or trainer. If your zones feel too hard or too easy after a test, the estimate is probably off, and adjusting it is reasonable.

What Causes FTP Numbers To Change Between Tests?

Your FTP estimate can shift for reasons that have nothing to do with fitness. Knowing this helps you avoid chasing noise.

Freshness is the biggest factor. A test done after a rest day will usually read higher than one done mid-training block. Time of day, sleep, hydration, and how motivated you feel all nudge the number too.

Equipment matters as well. A different power meter, a recalibration, or a change in indoor versus outdoor setup can move your result. If you switch devices, treat the first test as a new baseline rather than a comparison.

Body position and cadence also play a role. Riding in a different position or at a very different cadence changes the power you can produce.

Because of all this, small changes between tests are not meaningful. A few watts up or down is normal variation. A clear, consistent trend over several tests is what tells you something real is happening.