Training by feel is fine, but heart rate gives you an objective dial for effort. Zones turn that dial into a plan — telling you when to hold back for endurance and when to push for fitness.
TL;DR — Enter your age in the target heart rate calculator to see your max heart rate and five training zones.
Finding your max heart rate
Everything is anchored to your maximum heart rate. The calculator estimates it with the Tanaka formula — 208 minus 0.7 times your age — which holds up better across ages than the old “220 minus age” rule. A proper lab test is more accurate, but the estimate is plenty for everyday training.
What each zone trains
The five zones are slices of your max. The lower zones (50–70%) build an aerobic base and aid recovery — easy, conversational effort. The middle zones (70–80%) develop cardio fitness. The top zones (80%+) sharpen speed and power but are hard to sustain. A balanced program spends most time low, with smaller doses up high.
The fat-burn myth
You may have heard a “fat-burning zone” sells lower intensity as best for weight loss. It is half true: easy efforts use a higher proportion of fat, but hard efforts burn more total calories. For changing your body, total energy and consistency matter more than the zone label. Use the target heart rate calculator to set your zones, and train at intensities you can keep up.