Running Pace for Each Heart Rate Zone

Heart rate zones tell you how hard to run. They do not tell you how fast, and standing at the start of an easy run trying to work out what “zone 2” means in minutes per kilometer is the gap this page fills. Give it your heart rates and one recent race result, and it returns a pace range for each zone.

Step one: the heart rate zones

The Heart Rate Reserve method, also called the Karvonen formula, works from the span between your resting and maximum heart rates rather than from your maximum alone. It is noticeably more personal, because two runners with the same max can have resting rates 25 beats apart.

HRR       = Max HR − Resting HR
Target HR = Resting HR + (HRR × intensity%)

For a runner with a max of 188 and a resting rate of 55, HRR is 133. Zone 2 runs from 60 to 70% of that:

• Lower: 55 + (133 × 0.60) = 55 + 79.8 = 135 bpm
• Upper: 55 + (133 × 0.70) = 55 + 93.1 = 148 bpm

Step two: turning zones into paces

Pace comes from your threshold pace, which the calculator derives from the race you enter using Riegel’s endurance formula:

T2 = T1 × (D2 / D1)^1.06

That exponent, 1.06, is what makes a marathon slower per kilometer than a 10K rather than the same speed. Riegel fitted it across thousands of race results in 1977 and it has held up remarkably well for distances between about 1,500 m and the marathon.

Threshold pace, roughly the pace you could hold for an hour flat out, anchors the zones. Everything else is expressed as a percentage of that speed:

The honest caveat about all of this

The pace-to-heart-rate relationship is individual and it moves. It shifts with heat, humidity, altitude, hills, fatigue, caffeine, sleep and how long you have been running that day. The paces here are a starting point for a runner on flat ground in decent conditions, not a prescription.

Cardiac drift is the one that catches people

On a long run your heart rate climbs even though your pace has not changed. Over 60 to 90 minutes, dehydration and rising core temperature add 5 to 15 bpm at identical effort. That is normal, and the correct response is to slow down and hold the zone rather than hold the pace. Runners who chase the pace number on a hot day finish the second half of a long run in zone 4 without meaning to.

For the same reason, do not read too much into a single run where the zones and paces disagree. Look at the pattern over a few weeks.