FBA Dimensional Weight Calculator
Calculate dimensional weight from package dimensions using Amazon's divisor.
What is the FBA Dimensional Weight Calculator?
Amazon (and most carriers) charge shipping based on whichever is greater: a package's actual weight, or its "dimensional weight" — a volume-based weight calculated from the package's length, width and height. Large, lightweight items often get charged by dimensional weight instead of their real weight, which is why it's worth checking before you finalize packaging.
The formula
Dimensional weight (lb) = (Length × Width × Height, in inches) ÷ divisor. Amazon's FBA divisor for US domestic shipments is currently 139, the same divisor used by FedEx and UPS ground — this changed from 166 to 139 in January 2026, so if you're using an older figure, update it.
How to use it
- Enter your package's length, width and height in inches.
- Leave the divisor at 139 for current Amazon US FBA calculations, or change it for a different carrier/region.
- Optionally enter the actual scale weight to see which figure (dimensional or actual) is higher — that's the one you'll be billed on.
This tool calculates weight only, not Amazon's size/weight tier or fee amount, since those thresholds are updated by Amazon periodically — check your current tier in Seller Central's FBA revenue calculator once you know the dimensional weight.