Weighing panThe pan the object is placed on to be weighed.
100 gram beamThe middle and largest beam, marked in 100-gram steps.
10 gram beamThe far beam, marked in 10-gram steps.
1 gram beamThe front and smallest beam. It reads from 0 to 10 grams in fine steps.
RidersThe sliding weights on the beams. Where they sit shows the mass on the pan.
PointerThe pointer at the end of the beams. When it lines up with the zero mark, the beams balance the object.
Setting it up: 3 3
Zero markThe fixed mark the pointer must line up with. Both before weighing and when the reading is taken.
Zero adjustment knobSets the pointer on the zero mark with the pan empty. Used before you weigh anything.
BaseThe base under the pan and beams, which stands on the bench.
How this list was compiled: Read 2026-09-27. Wikipedia, Triple beam balance, https://en.wikipedia.org/wiki/Triple_beam_balance : named for its three beams, the middle the largest, the far beam medium and the front the smallest; typically the middle beam reads in 100 g steps, the far beam in 10 g steps and the front beam from 0 to 10 g; its parts: the weighing pan, base, beams, riders (the sliding pointers on the beams), the pointer, which marks the equal point, and the zero adjustment knob, used to set the pointer on the zero mark before use; the hundreds rider is set first, then the tens, then the ones until the pointer returns to zero. 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 triple beam balance, the kind used in school labs, drawn from the front with the pointer close up. Start with the 6 main parts.
Read the full guide
Setting it up
With the pan empty and every rider at zero, turn the zero adjustment knob until the pointer lines up with the zero mark.
Weighing
Put the object on the pan. Slide the rider on the 100 gram beam until the pointer drops, then back one notch; do the same on the 10 gram beam; then slide the 1 gram rider until the pointer is back on zero. Add up the three readings.
Start with the biggest beam: hundreds first, then tens, then ones.
Questions and answers
What are the three beams on a triple beam balance?
The middle beam, the largest, reads in 100-gram steps; the far beam in 10-gram steps; and the front beam, the smallest, reads from 0 to 10 grams.
What are the riders on a triple beam balance?
The sliding weights on the beams. You move them until the pointer lines up with the zero mark, and their positions add up to the object's mass.
What is the zero adjustment knob for?
It sets the pointer on the zero mark before you start, with the pan empty and the riders at zero, so the readings are true.