Operation Manual

14
Default heart-rate zones
Default heart-rate zones are calculated using your estimated maximum heart rate.
Fitbit calculates your maximum heart rate with the common formula of 220 minus
your age.
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Zone
Calculation
Description
Out of Zone
Below 50% of your
maximum heart
rate.
Your heart rate may
be elevated but not
enough to be
considered
exercise.
Fat Burn
Between 50% and
69% of your
maximum heart
rate.
Low-to-medium
intensity exercise
zone. This zone
may be a good
place to start for
those new to
exercise. It’s called
the Fat Burn zone
because a higher
percentage of
calories are burned
from fat, but the
total calorie burn
rate is lower.
Cardio
Between 70% and
84% of maximum
heart rate.
Medium-to-high
intensity exercise
zone. In this zone
you’re pushing
yourself but not
straining. For most
people this is the
exercise zone to
target.
Peak
Greater than 85%
of your maximum
heart rate.
High-intensity
exercise zone. This
zone is for short
intense sessions
that improve
performance and
speed.