How to choose electronic balance and how to check accuracy

Funny calibration guide from timemore:

20,100, 500, 1000, 2000g weights are used

No of bits of ADC is more important

Usually it's 24 bits eg in HX711, 

looks like this 24 bit ADC will give about 14 to 15 noise-free bits. 

ie range is say 2^14 to 2^15 usable. Arduino forum 

Eg a 0.01g minimum gradation 

The range is theoretically 0.01 to 163.84g, or 327.68g  so if it can measure up to 200g, the repeatability in this range is pretty safe.

Min grad can be misleading 

起稱範圍 is more important 

See reply below:

Eg this Balance claimed a 0.001g (1mg)

But initial is 0.005g

If possible, choose one with one more decimal digit.

Eg if you want to measure up to 0.01g, choose one that displays 0.001g

Btw, those cheap balance( under¥100), most can only repeatedly measure up to 0.01g, even it says 0.001g accuracy 

The weight 砝碼 provided with the kit is usually 100g ,M grade, ie 5% tolerance. This is pretty meaningless(~¥7). Just for demo purpose, and not good for calibration.

But if you want to measure 0.1g or less, better to use at least F2 grade weight(1.6% tolerance)

Hysteresis of load cell is something the seller never tells you

ADS1256 library on Arduino and STM32

CS1238, likely a clone of TI ADS123X， Arduino forum 

Calibration due to latitude , detail cause  up to 1.3%