Free box calculator

How many units fit in a box?

Enter your product's dimensions and the carton's inside dimensions to get units per box — with a live Amazon FBA 50 lb and box-size check.

Product unit

Carton (inside dimensions)

No account needed. Grid-fit method used by prep centers — units all one orientation.

How the box calculator works

It finds the orientation of your unit that packs the most into the carton, then caps by the marketplace's box weight limit.

1

Enter unit + carton

Your product's outer size and weight, and the carton's inside dimensions.

2

We fit it every way

All axis orientations are tried; the best fit wins. Weight caps it to the marketplace's box limit.

3

Get units per box

Plus the grid (L×W×H), cube utilization, full carton weight, and a pass/fail on the box rules.

Box calculator FAQ

How many units fit in a box?

Divide each carton inside dimension by the matching unit dimension, multiply the three whole-number results, and take the best orientation. This calculator does that across all orientations and then caps the count by the carton weight limit.

What's the Amazon FBA box weight limit?

50 lb for a multi-item box (a single oversized item may exceed it with a Team Lift label). This tool warns you if your filled carton would exceed the limit for the marketplace you pick.

What's the max box size for Amazon FBA?

25 inches on the longest side for standard multi-item boxes. The tool flags a carton whose longest side exceeds the selected marketplace's limit.

Does it account for how the items are packed?

It uses the standard grid method (all units in one orientation) that prep centers and FBA sellers use for planning. Mixed-orientation nesting can occasionally fit a little more.