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Calcimator

Smartwatch Battery Life Calculator

Estimate smartwatch battery duration based on battery capacity, display settings, GPS usage, heart rate monitoring, and connectivity features.

Inputs

Results

Battery life (days)

2.7

Workout mode (hours)

10.6

Battery life (hours)63.8
Avg power draw (mW)18.1
GPS-only mode (hours)12
Charges per year137
How to Use This Calculator
  1. Enter your smartwatch battery capacity (mAh) — check the manufacturer spec sheet or teardown data.
  2. Select display type (AMOLED, LCD, or MIP/transflective) and set brightness and screen-on time.
  3. Enter daily GPS usage (min/day), heart rate monitoring mode, and whether cellular LTE is enabled.
  4. Set your average daily notification count to account for Bluetooth and vibration motor draw.
  5. Review battery life in days and hours, average power draw (mW), and workout-mode duration.

How the result changes with Battery capacity (mAh)

Battery capacity (mAh)Battery life (days)Workout mode (hours)
1451.35.1
3833.413.6
6685.923.7
905832.1

What each input means

Battery capacity (mAh)
Battery capacity in milliamp-hours. Typical: Apple Watch ~300, Garmin Fenix ~400, Galaxy Watch ~360.
Display type
Select the display type
Always-on display
Select the always-on display
Brightness (%)
Display brightness level as a percentage.
Screen-on time (min/day)
Total minutes per day the display is actively on (not AOD).
GPS usage (min/day)
Average minutes per day using GPS (outdoor workouts, navigation).
Heart rate monitoring
Select the heart rate monitoring
Cellular (LTE)
Select the cellular (lte)
Notifications per day
Average number of push notifications received per day.

What each result means

Battery life (days)
Estimated battery duration in days with your usage pattern.
Battery life (hours)
Estimated battery duration in hours.
Avg power draw (mW)
Average continuous power consumption in milliwatts.
Workout mode (hours)
Battery life during active GPS workout with continuous HR.
GPS-only mode (hours)
Maximum hours of continuous GPS tracking.
Charges per year
Estimated number of charge cycles per year with this usage.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Battery capacity (mAh) = 300, Display type = 0, Always-on display = 0, Brightness (%) = 50 = 9 input(s) provided
  2. Calculate Battery life
    Battery life = batteryLifeHours / 24
    2.7 = 2.7
  3. Calculate Workout mode
    Workout mode = batteryWhCapacity / (workoutPowerMw / 1000)
    10.6 = 10.6
  4. Calculate Battery life
    63.8 = 63.8
  5. Calculate Avg power draw
    Avg power draw = basePowerMw + avgDisplayMw + avgGpsMw + avgHrMw + avgBtMw + avgCellularMw + v...
    18.1 = 18.1

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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