Capacity vs Resolution

Pick a cell rated for roughly 1.5 to 2 times your heaviest expected load. Going much bigger wastes resolution: a 20kg cell weighing coffee beans will be noisier per gram than a 1kg or 5kg cell, because the useful signal is a smaller slice of the ADC range.

Cell Type

Straight-bar (parallel beam) cells are 4-wire full bridges for 1 to 20kg platforms. Half-bridge 50kg cells are 3-wire and must be combined in pairs or fours. S-type cells handle pulling and pushing for hanging or in-line loads.

HX711 Board Quality

The HX711 runs from 2.6 to 5.5V, so it works with 3.3V ESP32 and Pico boards. Better boards split analog (VCC) and digital (VDD) supplies, add filtering and let you choose 10 or 80 samples per second. Most generic green boards are fixed at 10 SPS.

Mounting Hardware

A straight-bar cell must be bolted at one end to a base and at the other end to the weighing platform, with spacers so the middle can flex. Check the hole sizes (M4 and M5 are common) and whether plates or screws are included before you design your enclosure.

Pack Size & Spares

Overloading a small cell once can permanently bend it, and a cheap HX711 board can arrive with a bad solder joint. Two-set and four-set packs cost little more than a single kit and give you a spare plus a second project.

This is the 10kg version of our top pick, from the same listing family, again with two load cells and two HX711 boards. Ten kilograms is the right size when 5kg is too tight but 20kg throws away resolution: think plant-pot watering monitors, a shipping scale for small parcels, a smart shelf for a pantry jar, or a force rig for a robot gripper. Wiring and code are identical to the 5kg kit; only the calibration factor changes. Its perfect 5-star average comes from just a handful of ratings, so treat it as promising rather than proven.

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These are the flat, E-shaped sensors that sit in the four corners of a bathroom scale. Each is a 3-wire half bridge, so on its own it can’t drive the HX711; you wire four of them into one full Wheatstone bridge (one per corner of a platform) for a combined capacity of up to about 200kg, or use two for a smaller rig. That makes this kit the go-to for body-weight scales, beehive scales, bed-occupancy sensors and inventory platforms. With 68 ratings at about 4.1 stars it has one of the larger review bases here. Most complaints trace back to wiring or mounting: the centre button of each cell must be free to deflect, so the cells need proper seats rather than being glued flat.

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When you need more than two scales, ShangHJ’s four-set pack is the most economical way to get there: four 5kg cells and four HX711 boards. That suits classroom labs, multi-bin smart shelves, a row of plant pots or a test fixture that weighs several items at once. Each set is independent, so on an ESP32 you can read all four HX711s on separate data pins with a shared clock line. Ratings sit around 4.4 stars from a small sample, in line with other generic 5kg kits.

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A 1kg cell flexes much more per gram than a 5kg cell, so the same HX711 gives you finer resolution: with careful mounting and averaging, sub-gram readings are realistic. That makes this kit ideal for an espresso or pour-over scale, a 3D-printer filament remaining-weight monitor (for small spools), a mail scale for letters, or measuring small forces in a lab rig. The trade-off is fragility: leaning on it or dropping something heavy on the platform can overload and permanently bend the beam, so add a mechanical stop under the platform. It has about 4.5 stars from a small number of ratings.

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This is an amplifier only, with no load cell, and it is the upgrade we recommend when a generic green HX711 board gives you jittery readings. SparkFun’s design separates the analog supply (VCC) from the digital logic supply (VDD) and adds an inductor and capacitor filter on the digital rail, which noticeably cleans up noise, especially next to a Wi-Fi ESP32. It runs from 2.7 to 5V at under 1.5 mA, offers selectable 10 or 80 samples per second (most clones are stuck at 10), rejects 50 and 60Hz mains hum, and includes a YLW pin to ground a shielded load cell cable. SparkFun publishes a hookup guide, schematic and example code. With 77 ratings at about 4.6 stars, it is also the most-reviewed product in this guide.

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Bar and half-bridge cells only measure weight pressing down. An S-type load cell has a threaded hole at each end and measures pulling (tension) as well as pushing (compression), so you can hang a hopper, a feed bag or a hoist from it, put it in-line with a cable, or build a pull-force tester or thrust stand. It is a 4-wire full bridge, so it connects to any HX711 board exactly like a bar cell. Two caveats: this listing is the load cell alone (pair it with the SparkFun HX711 above), and it costs several times more than the hobby kits. The same page sells capacities from 50kg to 2000kg, so make sure the size you need is selected. About 4.4 stars from a small number of ratings.

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Building your first kitchen or feeder scale?

Start with the 5kg Load Cell + HX711 2-set kit. It matches most tutorials and gives you a spare.

Weighing heavy pots, jugs or produce?

Go for the Geekstory 20kg kit, or the 10kg 2-set kit if your loads stay under 10kg.

Body scale, beehive or inventory platform?

Use the 4× 50kg half-bridge set, one cell per corner, for up to about 200kg.

Need sub-gram precision?

Pick the 1kg kit for coffee, letter and lab scales, and add an overload stop.

Teaching a class or building several scales?

The ShangHJ 4-set pack gives the lowest cost per working scale.

Hanging load, cable tension or thrust stand?

Combine the S-type load cell with the SparkFun HX711 board.

Should I buy a 1kg, 5kg, 10kg or 20kg load cell?

Choose the smallest capacity that comfortably covers your heaviest load plus the weight of the platform and container, with roughly 1.5 to 2 times headroom. A 1kg cell suits coffee and letter scales, 5kg covers most kitchen, feeder and spool projects, 10kg handles small parcels and plant pots, and 20kg is for heavy pots and produce. Oversizing costs resolution; undersizing risks permanently bending the beam.

Does the HX711 work with an ESP32 or Raspberry Pi Pico at 3.3V?

Yes. The HX711 operates from 2.6 to 5.5V, so you can power the board from the 3.3V rail and connect DT and SCK to any two free GPIO pins without a level shifter. Excitation and therefore signal are a little lower at 3.3V, which slightly reduces resolution, but it is fine for hobby scales. On the ESP32, avoid boot-strapping pins and keep the board and cell wires away from the antenna to reduce noise.

How do I wire four 50kg half-bridge load cells to one HX711?

Each half-bridge cell has three wires: a centre tap (usually red) and two ends. Place one cell at each corner and connect them in a ring so that matching ends of neighbouring cells are joined; this forms a single full Wheatstone bridge. The two joined pairs on opposite sides become E+ and E-, and the centre taps of the remaining two cells become A+ and A-. Wire colors vary between suppliers, so confirm each cell’s centre tap with a multimeter (it reads roughly half the end-to-end resistance) before you solder. A small “combinator” breakout board makes this much tidier.

Why do my load cell readings drift or jump around?

The usual causes are mechanical, not electrical: a cell bolted flat without spacers, a flexible platform, or screws that loosen. After that come long unshielded leads, a noisy USB or Wi-Fi supply, and temperature change. Fix the mounting first, keep the leads short and twisted, average 10 to 20 readings in firmware, and give the scale a few minutes to warm up. If a generic board is still noisy, swap in a board with separate analog and digital supplies, such as the SparkFun HX711. Slow drift under a constant load is creep, which cheap cells show more than industrial ones.

How do I calibrate a load cell with the HX711?

Calibration is two steps. First, tare with the empty platform in place so the library records the zero offset. Second, place a known reference weight (ideally 30 to 50 percent of the cell’s capacity) and divide the raw reading by that weight to get your calibration factor. Store the factor and offset in EEPROM or ESP32 NVS so the scale survives a reboot, and repeat the calibration if you change the platform or mounting. Our HX711 weigh-scale ADC guide explains the gain settings and data format behind these numbers.