YF-S201 Water Flow Rate Sensor


This is a water flow rate sensor you can use with Arduino to measure rate of liquid flow through it.

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SKU: MDU-SEN-YF-S201 Category: Tags: ,


This sensor sits in line with your water line and contains a pinwheel sensor to measure how much liquid has moved through it. There’s an integrated magnetic hall effect sensor that outputs an electrical pulse with every revolution. The hall effect sensor is sealed from the water pipe and allows the sensor to stay safe and dry.

The sensor comes with three wires: red (5-24VDC power), black (ground) and yellow (Hall effect pulse output). By counting the pulses from the output of the sensor, you can easily calculate water flow. Each pulse is approximately 2.25 milliliters. Note this isn’t a precision sensor, and the pulse rate does vary a bit depending on the flow rate, fluid pressure and sensor orientation. It will need careful calibration if better than 10% precision is required. However, its great for basic measurement tasks.

The pulse signal is a simple square wave so its quite easy to log and convert into liters per minute using the following formula.

Flow Rate (L/min) = Pulse frequency ? 7.5


  • Built-in Hall effect pulse counter
  • Operating voltage : 5 – 12V
  • Current draw : <15mA
  • Output Type : Digital pulses
  • Operating flow rate: 1 – 30 Liters/Minute
  • Operating temperature range : -25 to +80?
  • Operating humidity range : 35 – 80% RH
  • Accuracy : ?10%
  • Maximum water pressure : 2.0 MPa
  • Output duty cycle : 50?10%
  • Output rise time : 0.04us
  • Output fall time : 0.18us
  • Pulses per Liter : 450
  • Durability : minimum 300,000 cycles
  • Cable length : 15cm
  • 1/2″ nominal pipe connections, 0.78″ outer diameter, 1/2″ of thread
  • Dimensions : 2.5″ x 1.4″ x 1.4″



VCC (Red)Power sourceConnect to 5V of system
OUT (Yellow or White)Output pulse signalConnect to any digital pin
GND (Black)GroundConnect to GND of system


Files & Documentation

Additional information

Weight25 g
Dimensions60 × 35 × 35 mm