Beatcast
Zone 2 heart rate calculator
Updated
What this does
This is the heart rate zones calculator, opened on zone 2. Enter your age, and optionally a measured maximum, a resting rate or a threshold. It shows your zone 2 range under several definitions. Everything runs in your browser. Nothing you type is sent, stored or logged.
The calculator
Whole years, 10 to 100.
How the zones are worked out.
Five is Beatcast's default.
Optional, 100 to 230 bpm. Left empty, the Tanaka estimate from your age is used.
Optional, 30 to 120 bpm. The Karvonen method needs it.
Optional, 80 to 220 bpm. Percent of threshold needs it.
Why there are four answers
Search for a zone 2 range and you will find numbers that disagree by 20 beats. Each answers a different question.
| Definition | Range | For age 40, resting 60 |
|---|---|---|
| Percent of maximum (Beatcast's Endurance zone) | 60 to 70% of max | 108 to 125 bpm |
| Percent of heart rate reserve | 60 to 70% of reserve, plus resting | 132 to 143 bpm |
| Maffetone's 180 minus age | A ceiling | 140 bpm |
| First threshold, measured in a lab | Where blood lactate first rises | Depends on the person |
Maximum comes from Tanaka for this example: 208 minus 28 is 180. Reserve is 180 minus 60, which is 120.
Percent of maximum. 60 and 70 percent of 180 give 108 and 126. In Beatcast the Endurance zone starts at 108 and runs up to, but not including, 126, so 125 is the last beat in it.
Percent of reserve. 60 plus 60 percent of 120 is 132, and 60 plus 70 percent is 144, so the range is 132 to 143.
Maffetone. Phil Maffetone's rule is 180 minus your age, which gives one number to stay under. It comes from his book The Big Book of Endurance Training and Racing.
Laboratory threshold. Researchers define zone 2 by where the body first shifts its fuel and lactate use, found with a test. That point can sit well away from any age formula. If you have one from a test, use it.
Which one to use
If you have a lab or field test, use that number. If not, pick one definition and keep it, so that your sessions are comparable. The talk test, speaking in full sentences, is a useful check alongside a number. If the number and the test disagree, believe your own sense of effort.
Age-based figures miss any one person by about 10 to 12 beats. See the heart rate zones calculator for the method and the sources.
These are training estimates. If you take medication that changes your heart rate or have a heart condition, ask your clinician before using age-based numbers. Beatcast is not a medical device.
Beatcast uses these same numbers
Beatcast's Endurance zone is zone 2, 60 to 70 percent of your maximum by default, or of your reserve if you choose Karvonen. Choose it as your target zone and set a ceiling alert, and the screen tells you when you drift above. A zone alert on it gives you a cue when you get there. See zone 2 training with a strap and an iPhone.
Beatcast on the App Store. Fourteen days free, then one purchase.
Questions
What is my zone 2 heart rate by age?
For a 40-year-old on Beatcast's default, 108 to 125 beats per minute. The other definitions give other numbers.
Is zone 2 the same as the aerobic zone?
Names differ between apps. Check the numbers, not the label.