Karvonen Formula Calculator - Target HR by Training Zone

A karvonen formula calculator turns age, resting heart rate, and a training intensity into the target heart rate for a session, plus a full five-zone chart you can read off a chest strap or sports watch. The reserve method multiplies the heart rate reserve by the chosen intensity and adds the resting heart rate back. Runners, indoor cyclists, and returning exercisers use it for easy, tempo, threshold, and interval sessions.

• • Run and ride zone planning: a runner or indoor cyclist who wants a target heart rate for an easy, tempo, or VO2 max interval.
• • Returning exerciser: a person rebuilding aerobic capacity who needs a conservative zone 1 and zone 2 reading.
• • Coach programming: a coach building a week of sessions and needing the full five-zone chart on a single page.
• • Watch cross-check: a watch or chest strap owner checking whether the device zones match the Karvonen zone ladder.

The reserve method is the modern alternative to the older 220 minus age percentage of maximum heart rate approach, and it lifts the easy and tempo zones by the resting heart rate to match how the body actually responds to light and moderate exercise.

After the calculator gives the target heart rate, the Running Pace Calculator helps pair it with a running pace for an easy, tempo, or threshold session.

The calculator applies the heart rate reserve math: estimate maximum heart rate from age using the modern Tanaka 2001 equation, subtract the resting heart rate to get the reserve, then take a percentage of the reserve and add the resting heart rate back. The same math runs at the same time for every zone in the five-zone chart.

• Age: Whole years used by the Tanaka 2001 age-predicted maximum heart rate equation.
• Resting heart rate: Beats per minute measured first thing in the morning or a 7-day average from a wrist or chest strap.
• Heart rate reserve: The difference between maximum and resting heart rate, the multiplier the formula applies the zone percentage to.
• Target heart rate: Beats per minute to hold during the session, computed as (HRR x intensity) + HRrest.

The reserve method and the percentage of maximum heart rate method give similar targets at zone 3 and above, but diverge at the easy and recovery end because the reserve approach adds the resting heart rate back as a floor.

According to Tanaka, Monahan, and Seals (AHA Journals, 2001), the age-predicted maximum heart rate is 208 minus 0.7 times age, with a standard deviation of about 10 bpm.

The Karvonen formula gives the heart rate, and the VO2 Max Calculator turns that training into a cardiorespiratory fitness number, since zone 4 and zone 5 reserve-ladder intervals are the work that raises aerobic capacity.

Four ideas explain why the reserve method works: the Tanaka 2001 maximum heart rate, the heart rate reserve, percent of reserve versus percent of maximum, and the five-zone chart.

A 10 bpm drop in resting heart rate can move the heart rate reserve up by 10 bpm and shift every zone boundary up by 7 to 10 bpm at the same age.

The percent of HRR and percent of HRmax are the two standard ways to write training zones, and the Target Heart Rate Calculator runs both at the same age and resting heart rate for a cross-check against the percent-of-maximum reading.

Enter the three inputs, pick a zone, and read the target heart rate. The full five-zone chart underneath is the same math run for every zone boundary.

1. 1 Enter your age: Type your age in whole years. The calculator uses the Tanaka 2001 equation.
2. 2 Enter your resting heart rate: Measure your pulse for 60 seconds first thing in the morning for three to seven days, or use the 7-day average from a chest strap.
3. 3 Pick the training zone: Use 50 to 60 percent of reserve for recovery, 60 to 70 percent for aerobic base, 70 to 80 percent for tempo, 80 to 90 percent for threshold, and 90 to 100 percent for VO2 max intervals.
4. 4 Read the target heart rate: The target heart rate is the beats per minute to hold for the session. The result panel updates as soon as you change any input.
5. 5 Compare to your watch: Set the corresponding manual zone on your sports watch or chest strap and confirm the device zone matches the calculator zone boundary.

A 30 year old with a 65 bpm resting heart rate planning a base run gets a 150 bpm target, 187 bpm HRmax, 122 bpm reserve, and zone boundaries of 126-138, 138-150, 150-163, 163-175, 175-187 bpm.

When the session is a clinical stress test, the ECG Heart Rate Calculator supports the medical reading the doctor or exercise physiologist uses alongside the zone chart.

The reserve method standardises the heart rate math, anchors the easy and tempo zones to the resting heart rate, and gives a single page to plan a training week.

• • Targets tied to the resting floor: The reserve approach adds the resting heart rate back as a floor, so easy and recovery zones match how the body responds to light exercise rather than underestimating the easy end.
• • Full five-zone chart on one page: The calculator returns the lower and upper boundary of all five zones from a single input set, so a coach or runner can plan a week of easy, tempo, threshold, and interval sessions.
• • Modern Tanaka 2001 HRmax: The age-predicted maximum heart rate uses the Tanaka 2001 equation with a 10 bpm standard deviation, which fits laboratory measured HRmax more tightly than the older 220 minus age rule of thumb.
• • Real-time watch cross-check: Reading the zone chart next to a sports watch or chest strap lets the user confirm the device zones match the calculator zones at the same age and resting heart rate.

The calculator returns the math, not a clinical test. Prescribed heart rate limits from a doctor or cardiologist should override the zone chart for diagnosed conditions, and the resting heart rate should be measured on a rested morning.

According to Mayo Clinic - Exercise intensity: How to measure it, target heart rate for a training zone uses the heart rate reserve method of HRmax minus HRrest multiplied by the target intensity plus resting heart rate, and the American Heart Association recommends a moderate zone at 50 to 70 percent of HRR and a vigorous zone at 70 to 85 percent.

A few practical factors shift the zone chart, and a few can change the same week as the session itself.

• • The age-predicted maximum heart rate has a standard deviation of about 10 bpm against laboratory measured HRmax, so the zone boundaries are a planning estimate and not a clinical test. A lab or field test gives a tighter answer for an athlete.
• • The percent of HRR and percent of HRmax methods disagree more at the easy and recovery end. The reserve method matches how the body responds to light exercise, but a device set to percent of HRmax will still read differently at zone 1 and zone 2.

Re-enter the resting heart rate whenever the average moves by 5 bpm or more, and update the age on the next birthday.

According to Karvonen, Kentala, and Mustala (1957 PubMed entry), target heart rate for a training intensity is best prescribed as a percentage of the heart rate reserve rather than as a percentage of maximum heart rate alone.