Heart Rate Zone Calculator

All six methods produce the same five training zones, but they differ in how much personal data they use and therefore how accurate the zones are for you specifically. The averaged option combines every method supported by the information you provide, giving greater weight to the more accurate models.

Age-Based Method (220 − Age)

At the simple end, age only estimates your maximum heart rate as 220 − age and scales each zone as a flat percentage of that number — fast, but the formula has a standard deviation of roughly ±10–12 bpm.

Karvonen Method (Heart Rate Reserve / HRR)

The Karvonen methods are more personalised: they incorporate your resting heart rate (RHR) via the heart rate reserve (HRR = max − resting), so the zone boundaries shift up or down with your fitness level. A well-trained runner with a resting HR of 45 bpm gets meaningfully different zones than a sedentary person with the same max HR of 180 bpm.

LTHR Method (Friel)

The Friel method anchors zones to a field-measured marker rather than a population average: it uses your lactate threshold heart rate — the average HR during the final 20 minutes of a hard 30-minute time trial — and sets zones as percentages of that anchor (72–120% LTHR).

MAF Method (Maffetone)

The MAF method takes a different approach: it sets your aerobic ceiling at 180 − age (with adjustments for health history and training experience) and builds all five zones around that single point, 10 bpm apart.

VT1/VT2 Thresholds Method

This method goes furthest of all: instead of scaling every zone off one anchor, it uses two individually tested breakpoints — your aerobic threshold (VT1, where blood lactate first rises above resting levels) and your anaerobic threshold (VT2, roughly your one-hour race effort). Zone 2 tops out exactly at VT1, Zone 3 runs from VT1 up to 90% of VT2, and Zone 4 closes the gap to VT2 itself. It's the most physiologically accurate method here, but also the most demanding to set up — VT2 in particular requires a genuine 30-minute time-trial effort.

Average of All Models

The averaged option combines every method for which you have supplied enough data. It uses an accuracy-weighted average rather than treating every estimate equally: tested VT1/VT2 thresholds receive the most weight, measured max-HR Karvonen and LTHR receive more weight than age-based estimates, and age-only and MAF receive the least. Add more measurements to include more models; methods without their required inputs are automatically excluded.

Curious why "220 − age" shows up everywhere despite having no scientific basis, or how these six methods actually compare? See Your Heart Rate Zones Are Probably Wrong.

Which Method Should You Use?

If you have a measured max HR and a reliable resting HR reading, Karvonen with measured MHR is the best general-purpose choice. If you've already tested both VT1 and VT2 — from a lab, a coach-supervised session, or a DFA-α1-capable HRV device — the thresholds method gives the most training-specific zones of any option here. Short on time for two tests but have a chest strap and a spare 30 minutes, the Friel LTHR method is a solid single-test alternative — it's measured with the same 30-minute time trial as VT2, so it's a natural fallback if VT1 is the one threshold you haven't pinned down. The MAF method suits runners who are deliberately building aerobic base and want a single simple ceiling to train below. Age-only is a reasonable starting point when you have nothing else.

What Do the Five Heart Rate Zones Mean?

Zone 1 (Recovery) and Zone 2 (Endurance) sit below your aerobic threshold (VT1) — easy enough to hold for hours, where fat metabolism, capillary growth, and mitochondrial density all improve efficiently. Zone 3 (Tempo) begins right at VT1: moderate aerobic effort that's broadly useful in small doses but easy to overuse — recreational runners often drift into it on days that should be easy. Zone 4 (Threshold) sits just below your anaerobic threshold (VT2), the hard, sustainable effort that raises race pace — roughly what you could hold for a solo hour. Zone 5 (VO₂max) is everything above VT2: near-maximal, short-interval effort. For why crossing VT1 changes how fast your heart rate actually recovers afterward, see Why Your Heart Rate Stays High Long After You Stop; for the physiology behind why training in these zones lowers your running heart rate over time, see How to Lower Your Heart Rate While Running.