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Know your zone with Forerunner 225 — the first Garmin GPS running watch with wrist-based heart rate¹. Now you have the option to run without a heart rate strap because this watch has a built-in sensor using Mio Heart Rate Technology that measures heart rate at the wrist.
We didn’t just get rid of the heart strap on the 225 — we also refined how this watch sums up your effort. A colorful gauge identifies your heart rate zone and beats per minute in real time: when it’s gray, you’re in your warm-up zone, which starts at 50 percent of your max heart rate; blue is your easy zone (starts at 60 percent of max); green is aerobic (starts at 70 percent of max); orange is threshold (starts at 80 percent of max); and red is your maximum zone, which starts at 90 percent of the maximum rate your heart can beat. If your training plan calls for running a set time or distance within a certain zone, you’ll appreciate this colorful interface that helps you see your zone at a glance so you can simply focus on your effort.
Out of the box, Forerunner 225 sets your zones based on your age-adjusted max heart rate estimate of 220 minus your age. You can adjust these zones either on the watch or at Garmin Connect, allowing you to customize your watch as needed. At Garmin Connect, our free online community, you can also create advanced workouts or download free training plans, send to your watch and get coach-like guidance.
Forerunner 225 uses an optical sensor (using Mio Heart Rate Technology) that shines light into your skin and then measures the amount of light returned. Because there are slight changes as blood pumps through your wrist, the sensor detects those changes and uses a sophisticated filtering process to determine your heart rate. A light seal on the back of the watch blocks out ambient light to help ensure proper heart rate detection.
In addition to using GPS to calculate distance and pace, the 225 has a built-in accelerometer. This allows it to capture distance and pace data when you’re running on an indoor track or treadmill, with no need for a separate foot pod accessory. It even doubles as an activity tracker¹, counting the steps and calories you burn all day. Plus, it will remind you to move if you’ve been sitting for more than an hour. When you get that cue to move, just walk for a couple of minutes to reset the inactivity indicator.