Depend. I will suggest to calibrate 1 time when you first get it. You may ask how? Get 2x2L soda and you will have 4 Kg of water = 8.8 lb. If your tension bar can go down to 8.8 lb, then you can calibrate with that. If not, 3x3L soda will do the trick. Tape all bottles together and hang it with a string and set the right tension to see if it will lift the bottles just off the ground and the tension bar should be level to the ground (or very close)
