Dimensional Weight Calculator
Carriers bill by the greater of actual weight or dimensional weight — how much space your package takes up. Oversized light boxes cost more than their actual pounds. This finds your billable weight and the cost impact.
Formula: dimensional weight = length × width × height (inches) ÷ divisor. Common divisors: 166 for USPS retail, 139 for UPS/FedEx daily rates. Billable: carriers charge the greater of actual or DIM weight, rounded up per package. Why it matters: a 2-lb item in an 18×14×12 box has DIM 18.2 lb (÷166) — a 9x cost jump. Consolidating or right-sizing boxes is the cheapest shipping optimization for light bulky items.
FAQ
What is dimensional weight?
A billing measure based on package volume instead of actual weight: length × width × height ÷ a carrier divisor. Carriers charge the greater of actual or DIM weight.
Why is my shipping cost so high for a light package?
Likely DIM weight. A light but oversized box bills at its volume-based weight, which can be many times its actual pounds. Use the smallest box that fits.
What divisor should I use?
USPS retail uses 166; UPS and FedEx daily rates use 139 (so DIM weight is higher). Your negotiated rate card may differ — use the divisor your carrier contract specifies.
Figures are editable example defaults for modeling, not quotes or advice. Financial, tax, and medical outcomes vary with your situation — verify with a qualified professional (CFP, CPA, tax advisor, or veterinarian).