Parts of a Scale – Beam, Fulcrum, Pointer, Pans and Weights

All 6 parts on the diagram

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Beam The bar across the top, balanced at its middle. A pan is hung from each end.
Fulcrum The fulcrum: the pivot the beam rocks on. On a good balance it is a hard knife-edge, so it turns almost without friction.
Pointer The pointer, fixed to the middle of the beam. It shows the smallest tilt: straight down means the two sides are equal.
Pans One holds the thing being weighed, the other the weights. Also called scale pans.
Weights Pieces of known mass. They are added to one pan until the beam is level.
Stand The stand, on its base, holding the fulcrum and the beam.

How this list was compiled: Read 2026-09-27. (1) Wikipedia, Weighing scale, https://en.wikipedia.org/wiki/Weighing_scale (Balance section): a balance compares the torque of the sample with that of standard reference masses using a horizontal lever, the beam; reference masses are hung on one end and the object on the other; the fulcrum is made nearly friction-free with a knife edge, and a pointer attached to the beam amplifies any deviation from balance; a center beam balance measures mass the same anywhere, because both sides feel gravity equally. (2) Encyclopaedia Britannica, 11th edition (1911), Weighing Machines, vol. 28 pp. 468-469, https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Weighing_Machines : equal-armed balances; the beam, the fulcrum knife-edge and the end knife-edges from which the scale-pans hang on chains; the stand; the weights; a horizontal pointer on the beam plays past a scale; the beam must be horizontal when the weights in the two pans are equal. Licence: own work

The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work

How it works

These are the parts of a scale on an equal-arm balance scale, the kind with two pans. It is level, so the apple weighs the same as the weights. Name all 6.

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How it balances

The beam rocks on the fulcrum, a hard knife-edge on top of the stand. A pan hangs from each end. Put the thing to weigh in one pan and add weights to the other until the beam is level.

Reading it

The pointer hangs from the middle of the beam and swings past a small scale on the stand. When it points straight down, both sides are equal, and the object's mass is the total of the weights.

A two-pan balance measures mass, not weight: it gives the same answer on the Moon, because gravity pulls both pans equally.

Questions and answers

What is the fulcrum on a balance scale?

The pivot the beam rests and rocks on. On an accurate balance it is a hard knife-edge, so the beam turns almost without friction.

What does the pointer on a balance do?

It shows when the beam is level. Being long, it turns a tiny tilt of the beam into a movement you can see.

How do you use a balance scale?

Put the object in one pan and add weights to the other until the pointer shows the beam is level. The object's mass equals the total of the weights.