HX711 Load Cell Amplifier & Load Cell
Build your own digital scale.
The HX711 is a 24-bit precision analog-to-digital converter (ADC) chip designed specifically for weigh-scale and industrial control applications. It amplifies and digitizes the tiny differential voltage produced by a load cell's Wheatstone bridge, turning raw strain-gauge signals into a clean digital reading a microcontroller can use. Paired with a bar-type or button load cell, it's the standard combo for building a DIY digital kitchen scale, a bench scale, or a weight-triggered trigger for automation projects.
Specifications
| ADC resolution | 24-bit |
| Operating voltage | 2.6V–5.5V (module regulator allows 5V logic and supply) |
| Operating current | ~1.5 mA active, <1 µA in power-down |
| Sample rate | 10 SPS or 80 SPS, selectable via the RATE pin |
| Input channels | Channel A (gain 128 or 64), Channel B (gain 32) |
| Interface | Simple 2-wire synchronous serial (DT/SCK, bit-banged — no dedicated hardware peripheral needed) |
| Load cell type | Any 4-wire Wheatstone-bridge load cell (bar, S-type, button, or half-bridge pair) |
| Typical load cell range | 1 kg, 5 kg, 10 kg, 20 kg, or 50 kg bar cells are the most common hobbyist sizes |
Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power, 2.6–5.5V DC |
| 2 | GND | Ground |
| 3 | DT | Data output — serial data line, read by the microcontroller |
| 4 | SCK | Serial clock input — clocks out each data bit and also selects gain/channel via pulse count |
| 5 | E+ | Load cell excitation positive — wire to the load cell's red wire |
| 6 | E- | Load cell excitation negative — wire to the load cell's black wire |
| 7 | A+ | Channel A positive input — wire to the load cell's white wire |
| 8 | A- | Channel A negative input — wire to the load cell's green wire |
Most breakout boards label the load cell terminal block as E+/E-/A+/A- and expect the standard 4-wire color code (red=E+, black=E-, white=A+, green=A-); some load cells swap green/white, so if readings are unstable or negative, try swapping A+ and A-. Channel B (B+/B-) is present on the HX711 IC itself but is rarely broken out on cheap modules.
Variants
Choose the HX711 for its huge community support, countless Arduino library examples, and rock-bottom price. Reach for the NAU7802 only if you specifically need I2C and want to free up two GPIO pins, since it needs more careful library setup and is less common in tutorials.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| HX711 breakout + 1kg bar load cell kit | ~$2-4 | ||||
| HX711 breakout + 5kg/10kg/20kg load cell | ~$3-6 | ||||
| NAU7802 | ~$3-5 |