Rotary encoder resolution calculator
Quadrature decoding multiplies an encoder resolution by four. Whether your counter does that decides half the answer.
rpm
MHz
Counts per revolution
4096
- Angular resolution
- 0.087 891 degrees
- Linear resolution
- 0.001 221
- In micrometres
- 1.221
- Count rate at maximum speed
- 204.80 kHz
- Maximum speed the counter allows
- 14 648 rpm
- Within the counter limit
- 1
- Linear speed
- 250.00 mm/s
Show the working
- Pulses per revolution = 1024
- Decoding = 4
- Maximum speed = 3000
- Screw lead or wheel circumference = 5
- Gear ratio = 1
- Counter input limit = 1
- Counts per revolution = 1024 * 4 = 4096
- Angular resolution = 4096 > 0 ? 360/4096 : 0 = 0.087 890 6
- Linear resolution = 4096 > 0 ? 5 / (4096 * 1) : 0 = 0.001 220 7
- In micrometres = 0.001 220 7 * 1000 = 1.2207
- count_rate = 4096 * 3000 / 60 = 204 800
- Count rate at maximum speed = 204 800 / 1000 = 204.8
- Maximum speed the counter allows = 4096 > 0 ? 1 * 1e6 * 60 / 4096 : 0 = 14 648.4
- Within the counter limit = 204 800 <= 1 * 1e6 ? 1 : 0 = 1
- Linear speed = 3000 / 60 * 5 / 1 = 250
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
Scenarios & local history
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The formula
- counts = pulses per revolution x decoding factor
- count rate = counts x rpm / 60
PPR and CPR are used inconsistently by manufacturers. Check whether a quoted figure already includes quadrature.
Encoder resolution is not accuracy. Bearing runout, coupling backlash and screw error all sit on top of it.