Heart Rate Reserve (HRR) Calculator

Calculate your Heart Rate Reserve and personalized training zones for more effective endurance training. More accurate than basic age-formula methods used by coaches and athletes worldwide.

Quick Answer: HRR = Max HR - Resting HR. Example: 190 max - 60 resting = 130 HRR. Zone 2 target = 60 + (130 × 0.6 to 0.7) = 138-151 bpm. More accurate than simple % of max HR.

Enter Your Details

I know my actual max heart rate

Age (years)

We'll estimate your max HR using 220 - age

Resting Heart Rate (bpm)

Measure first thing in the morning before getting up

What is Heart Rate Reserve?

Heart Rate Reserve (HRR) is the difference between your maximum heart rate and your resting heart rate. This value represents your heart's working capacity - the range through which your heart rate can increase during exercise.

The HRR Formula

HRR = Maximum Heart Rate - Resting Heart Rate

Target HR = Resting HR + (HRR × intensity percentage)

Why Use HRR?

Personalized accuracy: Accounts for individual fitness levels through resting heart rate
Better zone precision: More accurate than simple percentage of max HR
Fitness tracking: As fitness improves, resting HR decreases and HRR increases
Professional standard: Used by coaches, athletes, and sports scientists worldwide
Individual differences: Two people of the same age can have very different HRR values

Understanding Your Training Zones

Zone 1 (50-60% HRR) - Active Recovery

Very easy pace, conversational, promotes blood flow and recovery

Zone 2 (60-70% HRR) - Aerobic Base

Easy pace, build endurance, fat burning, foundation training

Zone 3 (70-80% HRR) - Aerobic Endurance

Moderate pace, tempo runs, improving aerobic capacity

Zone 4 (80-90% HRR) - Lactate Threshold

Hard pace, comfortably hard, race pace training

Zone 5 (90-100% HRR) - VO2 Max

Very hard intervals, maximum aerobic capacity, short efforts

Frequently Asked Questions

What is Heart Rate Reserve (HRR)?

Heart Rate Reserve (HRR) is the difference between your maximum heart rate and resting heart rate. It represents the range your heart rate can increase during exercise and is used to calculate personalized training zones that account for your individual fitness level.

How is HRR different from the Karvonen Formula?

HRR and the Karvonen Formula are essentially the same method. Both calculate training zones using heart rate reserve (max HR minus resting HR). The Karvonen Formula is simply the mathematical application of HRR principles, developed by Finnish exercise physiologist Martti Karvonen.

How do I measure my resting heart rate accurately?

Measure your resting heart rate first thing in the morning before getting out of bed. Use a heart rate monitor or take your pulse for 60 seconds. Track it for 3-5 consecutive days and use the average for most accurate results. Make sure you're well-rested and not sick.

Should I use age-estimated or tested max heart rate?

A tested maximum heart rate is always more accurate than age-based estimates like 220-age. If you've done a proper max HR test or observed your highest heart rate during intense training or racing, use that actual value instead. The 220-age formula can be off by 10-20 bpm for many individuals.

What are the HRR training zones used for?

Zone 1 (50-60% HRR) for active recovery between hard sessions, Zone 2 (60-70%) for aerobic base building (most training volume), Zone 3 (70-80%) for aerobic endurance and tempo work, Zone 4 (80-90%) for lactate threshold and race pace training, and Zone 5 (90-100%) for VO2 max intervals and maximum effort.

How often should I recalculate my HRR zones?

Recalculate your HRR zones every 8-12 weeks or whenever you notice significant fitness changes. As your fitness improves, your resting heart rate typically decreases, which increases your HRR and adjusts your training zones. Also recalculate if you've done a new max HR test.

Is HRR more accurate than percentage of max HR?

Yes, HRR-based zones are generally more accurate than simple percentage of max HR because they account for resting heart rate, which reflects individual fitness level. A person with a lower resting heart rate (better fitness) will have different training zones than someone with a higher resting rate, even if they have the same max HR.

Can I use HRR zones for both running and cycling?

While you can use HRR zones across different sports, your maximum and resting heart rates may differ between cycling and running. For most accuracy, measure sport-specific values if possible. Cycling max HR is typically 5-10 bpm lower than running max HR for the same individual.