here is the method from the reply above that turned into a long post about calibration
this method might not work with your scales, but in my experience it covers most low/mid end scales.
you will need, at least, a calibration weight that weighs the same as the rating of your scales. usually that rating is written on the scale somewhere. if it is not called something like "max", then you are looking for a pair of numbers that look something like "20g x 0.001g". the bigger number of the two, "20g" in this example, is the max weight rating of your scales. the smaller number is the resolution (or "division" or "d"
, so the scale in the example will measure in increments of 0.001g.
it is worth noting that the resolution is not solely responsible for the accuracy of the scale. the accuracy will be the result of a combination of the resolution and the precision. you should be able to find the precision in the manual or specs somewhere and it will be written as a weight, such as "±0.02g", or as a percentage, like "±0.01%".
it is also worth having a calibration weight that is half of your scales rating so you can test the scale at half weight after calibration.
do not use coins or other alternatives to calibrate your scales. there are a lot of suggestions to do this online, but most objects are not exact weights, particularly coins that are collecting dirt and chipping off chunks being handed around thousands of people before they get to you. on that note, take good care of your calibration weights so they stay clean and undamaged.
you will also want to make sure you get weights that fall into the correct tolerance classes for your needs. if the supplier is not clear about the class of the weights they are selling then go elsewhere.
there are a couple of different standards you can go by, most of the information you are likely to need is in the following chart.
M1 is usually fine. sometimes i get F2, but the price increases drastically the more accurate you need to be.
now finally on to the actual process for calibrating scales without proper instructions:
first you need to figure out which button triggers calibration mode if it is not clearly labelled. usually it is labelled something like "mode" or similar. you can try it by holding the button down for a couple of seconds. if it is the correct button then something will appear on the screen, most likely something like "cal".
once you know which button it is you can follow the steps below. below i will refer to the button as the "calibrate" button.
1. starting with the scale turned off, make sure the plate is clear and press the power button to turn the scale on.
2. press and hold the "calibrate" button for about 2 seconds. - a word similar to "cal" should appear on the screen at this point.
3. this is your chance to double check the plate to make sure there is nothing at all on there. once you are happy the plate is clean and there are no other disruptions to the scale then you can press the "calibration" button again.
4. usually at this point the needed calibration weight will appear on the screen (which is also the max rating of the scale as mentioned above). now you can place your calibration weight on the plate.
5a. once the scale settles there will be some indication on the screen, for example the number will flash, or stop flashing if it was previously flashing. you may now remove the weight and your scales should be good to go.
5b. i highly recommend testing to check that the calibration went well using at least one other weight at half the capacity of the scales.
if you have high quality scales the process may be more complex than the above, but if you have those scales then you will also have a good manual that explains the process well.
the above also only covers the bare minimum of proper calibration. it is enough for most uses but if you require more accuracy then you will need to do a full calibration and tests with a range of weights to get a more accurate view of the curve of the scale and the accuracy of the results. some scales will do some of this as part of their calibration process, or you can do it the old school way with a pen and paper, but most of us do not need to go that far and this post has got long enough without explaining that (there are good resources online if you want to know).
poorer quality scales will need to be calibrated more frequently. and if you move your scale you should always calibrate it before using it again.
the importance of calibration is often overlooked. it does not matter how good your scales are if they need to be calibrated, and on top of that the performance of low quality scales can be somewhat significantly improved with regular calibration.
that was not supposed to be that in depth. sorry guys
