HC-SR04 ultrasonic distance sensor front view with T and R transducers and Vcc, Trig, Echo, Gnd pins

HC-SR04 Ultrasonic Distance Sensor Module

$2.79 NZD

HC-SR04 Ultrasonic Distance Sensor Module

SKU: HCSR04-1PK

HC-SR04 Ultrasonic Distance Sensor Module

Name: HC-SR04 Ultrasonic Distance Sensor Module
Brand: NZN Electronics
SKU: HCSR04-1PK
Price: 2.79 NZD
Availability: InStock
Rating: 5.0 (1 reviews)

$2.79 NZD

5.0 1 review

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Easy 30-day returns · 12-month warranty

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The HC-SR04 is an ultrasonic distance sensor that measures from 2 to 400 cm by timing a 40 kHz sound pulse. It needs no library or calibration: one pin starts a reading and another returns a pulse whose length is the distance. It runs on 5V and wires straight to an Arduino; on 3.3V boards such as the ESP32 or Raspberry Pi, add two resistors to the Echo pin.

Specifications

ModelHC-SR04 ultrasonic module

Supply5V DC

Working currentAbout 15 mA

Measuring range2 to 400 cm

ResolutionAbout 3 mm

Beam angleAbout 15 degrees

Frequency40 kHz

TriggerHIGH pulse of at least 10 µs on Trig

Echo output5V pulse, width = round trip time

PinsVCC, Trig, Echo, GND, 2.54 mm header

Reading intervalAt least 60 ms apart

SizeAbout 45 x 20 x 15 mm

Datasheets

Full technical datasheetPDF Quick Start guidePDF

What's in the box

1×

HC-SR04 ultrasonic sensor module

4-pin header fitted. Jumper wires not included.

Great for

Stopping a robot car before it hits a wall

A parking distance alarm in the garage

Checking the level in a bin or hopper from above

Counting people through a doorway

Turning on a light when someone walks up

Showing students the speed of sound

Wiring & getting started

Find the pins
With the two round transducers facing you and the pins pointing down, the pins are VCC, Trig, Echo, GND from left to right. The names are also printed on the back.
Wire to an Arduino
VCC to 5V, GND to GND, Trig to D9 and Echo to D10. Our female-to-male jumper wires plug straight onto the header.
On an ESP32, Pico or Raspberry Pi
Keep VCC on the 5V pin. Trig can go straight to a 3.3V output. Run Echo through a 1k resistor to your input pin, with a 2k resistor from that pin to GND.
Take a reading
Send a 10 µs HIGH pulse on Trig, then read the Echo pulse with pulseIn(echoPin, HIGH, 30000). Divide the microseconds by 58 for centimetres. Point it at a wall about a metre away and the number should hold steady.

Frequently Asked Questions

Answers to the questions buyers ask most.

Will it work with an ESP32, Pico or Raspberry Pi?

Yes, with two resistors. Power VCC from the board's 5V pin, not 3V3. Trig is happy with a 3.3V output, but Echo comes back at 5V, which is too much for a 3.3V input. Put a 1k resistor from Echo to your input pin and a 2k resistor from that pin to GND, or use a level shifter.

How far and how accurately does it measure?

From 2 to 400 cm, to about 3 mm, on a flat hard surface facing the sensor. Closer than 2 cm it cannot read at all. Soft things like cloth, foam and fur, and surfaces angled away from the sensor, shorten the range.

How do I turn the Echo pulse into a distance?

Measure how long Echo stays HIGH in microseconds and divide by 58 for centimetres (or 148 for inches). In Arduino code that is pulseIn(echoPin, HIGH, 30000) / 58.0. The 30000 is a timeout, so a missed echo returns 0 instead of stalling your sketch for a second.

How often can I take a reading?

Leave at least 60 ms between readings, which is up to about 16 a second. Firing faster lets the previous echo arrive late and gives false short readings. About 10 readings a second suits most projects.

Why do I get 0 or jumpy readings?

0 usually means no echo came back: the target is too far, too soft, at a steep angle or closer than 2 cm. Jumpy numbers often come from readings fired too close together or a loose ground. Check the wiring, aim at a flat wall and average a few readings.

Is there an Arduino library for it?

You do not need one, but the NewPing library in the Arduino Library Manager makes it tidier and can filter out odd readings. In ESPHome and Home Assistant it works with the built-in ultrasonic sensor platform.

Can I use it in a water tank or outside?

Only if it stays dry. The board and transducers are open, so condensation or rain will upset or damage it. For a tank, mount it in a dry, sheltered spot above the water.

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I'm Lukas, an engineering student and maker based in Te Awamutu. NZN grew out of a CNC build that dragged on for months because every missing cable, bolt or electronic part meant another overseas order. I started the shop so Kiwi makers can spend more time building and less time waiting for the next parcel.

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