Heart Rate Zone Calculator
Calculate your five heart rate training zones based on age and resting heart rate using the Karvonen method.
This free online heart rate zone calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
Measure in the morning before getting out of bed.
Results
Max Heart Rate
190 bpm
Zone 1 (Recovery) Low
128 bpm
Zone 1 (Recovery) High
140 bpm
Zone 2 (Aerobic) High
153 bpm
Zone 3 (Tempo) High
165 bpm
Zone 4 (Threshold) High
178 bpm
Zone 5 (Max) High
190 bpm
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Heart Rate Zone Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Heart Rate Zone Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
Heart Rate Zone Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the Heart Rate Zone Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
About This Calculator
The Heart Rate Zone Calculator is a free, browser-based calculation tool for engineers, students, and technical professionals. Calculate your five heart rate training zones based on age and resting heart rate using the Karvonen method. It implements standard formulas and supports both metric (SI) and imperial unit systems with automatic unit conversion. All calculations are performed instantly in your browser with no data sent to a server. Use this calculator as a quick reference and sanity-check tool during design, analysis, and learning. Always verify results against primary engineering references and applicable standards for any safety-critical application.
About Heart Rate Zone Calculator
Heart rate training zones divide your exercise intensity into five bands based on percentages of your heart rate reserve. Training in different zones produces different physiological adaptations: Zone 1 promotes recovery, Zone 2 builds aerobic base, Zone 3 improves tempo endurance, Zone 4 raises lactate threshold, and Zone 5 develops maximum cardiovascular capacity. The Heart Rate Zone Calculator uses the Karvonen method, which accounts for both your maximum heart rate and resting heart rate to produce more personalized zone boundaries than methods based on max heart rate alone. Athletes, coaches, and recreational exercisers use heart rate zones to structure workouts, prevent overtraining, and ensure training variety.
The Math Behind It
Formula Reference
Karvonen Formula
Target HR = Resting HR + (HRR x %Intensity)
Variables: HRR = Max HR - Resting HR; Max HR = 220 - Age; Intensity ranges: Z1 50-60%, Z2 60-70%, Z3 70-80%, Z4 80-90%, Z5 90-100%
Worked Examples
Example 1: Zones for a 30-year-old with resting HR of 65
Age = 30, Resting HR = 65 bpm.
Five zones ranging from 128 bpm (easy recovery) to 190 bpm (maximum effort).
Common Mistakes & Tips
- !Using 220 minus age as an exact value; it is an estimate with a margin of error of 10-12 bpm.
- !Measuring resting heart rate after caffeine or stress; measure first thing in the morning.
- !Training exclusively in Zone 3 (the gray zone), which is too hard for recovery but too easy for speed development.
Related Concepts
Used in These Calculators
Calculators that build on or apply the concepts from this page:
Frequently Asked Questions
Which zone should I train in most?
Most endurance coaches recommend 80% of training in Zones 1-2 (easy/aerobic) and 20% in Zones 4-5 (hard). This polarized approach builds fitness while allowing adequate recovery.