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Calcimator

Fitness Tracker Accuracy Calculator

Estimate step-counting and heart-rate measurement accuracy based on sensor quality, wear fit, activity type, and skin tone.

Inputs

Results

Step accuracy (%)

96.82

Heart rate accuracy (%)

94

Step MAPE (%)3.18
Estimated step error318
HR MAPE (%)6
HR error (bpm)4.3
Overall accuracy score95.13
Steps Reported10,159
Steps Reported Mid9,841
Hr Reported Estimate74.2
How to Use This Calculator
  1. Set the accelerometer/PPG sampling rate (Hz) matching your wearable's specification.
  2. Select your activity type (walking, running, cycling, elliptical, or weight training).
  3. Rate wrist fit tightness (1–10) and your Fitzpatrick skin type — both affect optical sensor accuracy.
  4. Choose the number of sensor LEDs and enter your reference step count and actual heart rate.
  5. Review estimated step accuracy (%), HR accuracy (%), and error values to benchmark your device.

How the result changes with Sensor sampling rate (Hz)

Sensor sampling rate (Hz)Step accuracy (%)Heart rate accuracy (%)
2194.9890.52
7196.8294
13096.8294
18096.8294

What each input means

Sensor sampling rate (Hz)
Accelerometer/PPG sampling frequency in Hz. Most consumer devices use 25-100 Hz.
Activity type
Select the activity type
Wrist fit tightness (1-10)
Select the wrist fit tightness (1-10)
Fitzpatrick skin type (1-6)
Select the fitzpatrick skin type (1-6)
Number of sensor LEDs
Select the number of sensor leds
Actual steps taken
Reference step count to estimate the tracker's reporting error.
Actual heart rate (bpm)
True heart rate to compare against wearable reading.

What each result means

Step accuracy (%)
Estimated percentage accuracy of step counting (100% = perfect).
Step MAPE (%)
Mean Absolute Percentage Error for step counting.
Estimated step error
Expected absolute step-count error for the given actual steps.
Heart rate accuracy (%)
Estimated percentage accuracy of optical HR measurement.
HR MAPE (%)
Mean Absolute Percentage Error for heart rate.
HR error (bpm)
Expected heart-rate error in beats per minute.
Overall accuracy score
Weighted composite score: 40% step accuracy + 60% HR accuracy.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Sensor sampling rate (Hz) = 50, Activity type = 0, Wrist fit tightness (1-10) = 7, Fitzpatrick skin type (1-6) = 3 = 7 input(s) provided
  2. Calculate Step accuracy
    Step accuracy
    96.82 = 96.82
  3. Calculate Heart rate accuracy
    Heart rate accuracy
    94 = 94
  4. Calculate Step MAPE
    3.18 = 3.18
  5. Calculate Estimated step error
    Estimated step error
    318 = 318

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

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