Five training zones.. Heart Rate Zones is a free online tool from the ToolsRift Finance & Health Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Enter your age and resting heart rate. The calculator estimates your maximum heart rate and shows the five training zones with their heart rate ranges.
A common estimate is 220 minus your age, though individual maximums vary. Some tools also use the Karvonen method with your resting heart rate for more accuracy.
Zones range from very light recovery (about 50–60% of max) up to peak effort (90–100%), each targeting different goals like fat burn, endurance or performance.
Karvonen uses heart rate reserve (max minus resting) to set zones, giving more personalised targets than a plain percentage of maximum heart rate.