Is weight counting right for your parts? An honest checklist.
Counting by weight is accurate for most small parts, but not all. Check your parts before you buy, using the same numbers we use to size a system.
Weight counting works when each part type has its own bin, each part weighs about the same, and one part weighs more than the scale's resolution of 0.2% of capacity (±10 g on a 5 kg scale). Bins of up to about 50 parts count with near-zero error, 100 to 200 parts to about ±1 part, and 300 parts to about ±5 parts.
What four things decide whether weight counting works?
One part type per bin?
Mixed bins cannot be counted by weight.
Consistent weight?
Each part should weigh about the same as the next.
Heavier than the resolution?
One part should outweigh the scale's resolution.
How many per bin?
Accuracy is tightest on smaller quantities.
How accurate is counting by weight?
| Parts in the bin | Typical count accuracy |
|---|---|
| Up to 50 | About zero error |
| 100 to 200 | About ±1 part |
| 300 | About ±5 parts |
Which scale capacity suits which part?
| Capacity | Resolution | One part should weigh more than |
|---|---|---|
| 5 kg | ±10 g | 10 g |
| 10 kg | ±10 g | 10 g |
| 20 kg | ±20 g | 20 g |
| 30 kg | ±30 g | 30 g |
| 50 kg | ±50 g | 50 g |
Light parts suit 5 or 10 kg platforms; heavier parts count reliably on higher capacities.
Which parts work and which don't?
Counts well
Bolts, nuts, washers, rivets, pipe fittings, bearings, seals, terminals, connectors, and boxed or packed consumables.
Count in packs
Very light parts such as small O-rings, springs or labels. Set the sealed pack as the unit.
Not a good fit
Mixed bins, cut-to-length stock, and items too big for a bin.
Frequently asked questions
What if my parts are lighter than the scale's resolution?
Use a lower-capacity scale, or stock the parts in sealed packs and set the pack as the unit. A pack of 100 small O-rings counts reliably even when one O-ring does not.
Can one bin hold more than one part number?
No. Each bin needs a single part type so the total weight can be divided by one unit weight.
Do parts with varying weight work?
Parts that vary a lot, such as cut lengths of hose or cable, do not count reliably by weight. Pre-cut or packed items with a consistent weight do.
Can you check my parts before I buy?
Yes. Send part weights and typical bin quantities through the quote form and we will tell you which capacity to use, or whether weight counting is the wrong fit.
Related guides
Send us your part weights.
We will tell you which scales to use, and say so if weight counting isn't right for a part.