Cycling Heart Rate Zone Calculator

What the cycling heart rate zone calculator does

Cyclists train by heart rate zones, and the zones used in cycling are built on a different anchor from the general fitness ones. This tool builds them. You give it your lactate threshold heart rate, known as your LTHR, and it returns your cycling training zones as beats-per-minute ranges, from active recovery up through the high-intensity 5c zone.

It follows the well-known seven-zone system used widely in cycling, which is anchored on your threshold rather than your maximum, for reasons that are worth understanding.

How to use it

1. Enter your lactate threshold heart rate (LTHR) in beats per minute.

If you do not know your LTHR, the section below explains a simple test you can do yourself to estimate it. Press Calculate for your zones, or Reset to clear the field.

Why it uses LTHR, not max heart rate

General heart rate zone tools anchor everything on your maximum heart rate, but cycling zones are built on your lactate threshold heart rate instead, and there is good reasoning behind it. Your threshold, the effort where lactate starts to accumulate, is more closely tied to your endurance performance and your training than your maximum is. It is also far more practical to measure: pushing to a true maximum is brutally hard and a bit risky, while your threshold can be estimated from a sustained hard effort that you can actually repeat as your fitness changes. Anchoring the zones to that threshold makes them more meaningful for the kind of sustained efforts cycling is built around.

How to find your LTHR

You do not need a laboratory. The common field test is a solo time trial of about 30 minutes, ridden alone and at the hardest steady effort you can hold the whole way, with no one to chase and no downhills to coast. Start your heart rate recording, and after the ride take your average heart rate over just the final 20 minutes of the effort. That figure is a good estimate of your lactate threshold heart rate. It should be done when you are fresh and well warmed up, and because it is a genuinely hard effort, it suits riders who are already used to that kind of intensity. Repeat it every so often, since your threshold moves as your fitness does.

The seven zones

Each zone is a band expressed as a percentage of your LTHR, and each trains something different.

• Zone 1, Active Recovery, below about 81 percent. Very easy spinning to recover.
• Zone 2, Endurance, roughly 81 to 89 percent. The all-day aerobic base pace.
• Zone 3, Tempo, roughly 90 to 93 percent. A purposeful, moderately hard effort.
• Zone 4, Lactate Threshold, roughly 94 to 99 percent. Right at the edge you can sustain, the heart of raising your threshold.
• Zone 5a, above threshold, around 100 to 102 percent, into harder territory.
• Zone 5b, Aerobic Capacity, around 103 to 106 percent, the realm of VO2 max intervals.
• Zone 5c, Anaerobic Capacity, above about 106 percent, for short, very hard bursts.

An example with real numbers

Say your LTHR comes out at 160 beats per minute. The zones would land roughly like this:

• Active Recovery: below about 130 bpm
• Endurance: about 130 to 142 bpm
• Tempo: about 144 to 149 bpm
• Lactate Threshold: about 150 to 158 bpm
• Zone 5a: about 160 to 163 bpm
• Zone 5b: about 165 to 170 bpm
• Zone 5c: above about 170 bpm

So an easy endurance ride for this rider sits in the 130s, while a threshold interval pushes into the mid 150s. Your own zones simply scale with your LTHR.

A note on the numbers

These zones are only as current as the LTHR they are built on, and your threshold shifts as your fitness changes, so it is worth re-testing every couple of months and updating the number. The boundaries themselves are guides rather than hard walls, and pairing them with how an effort feels keeps you honest. Since the LTHR test is a hard, sustained effort, it is sensible to check with a doctor first if you are new to that kind of intensity, have a heart condition or other health concern, or take any medication that affects your heart rate, which can shift these numbers.

Questions people ask

What is LTHR?

Lactate threshold heart rate, the heart rate at the effort where lactate begins to build up faster than your body clears it. Cycling zones are anchored on it rather than on maximum heart rate.

How do I find my LTHR?

Ride a solo 30-minute time trial at the hardest steady effort you can hold, and take your average heart rate over the final 20 minutes. That average is a good estimate of your LTHR.

Why not just use my maximum heart rate?

Because threshold is more closely tied to endurance performance and is far easier and safer to test repeatably. Cycling training is built around sustained efforts, which the threshold reflects better than the maximum.

How often should I re-test?

Every couple of months, or whenever your fitness clearly changes. Your threshold rises with training, so updating your LTHR keeps the zones accurate.

References

1. Allen, H., & Coggan, A. (2010). Training and Racing with a Power Meter (2nd ed.). VeloPress. Lactate-threshold-based cycling training zones.