FedEx Dimensional Weight Calculator
See how FedEx bills your package: DIM weight with the official 139 divisor, billable weight, and the Additional Handling and Oversize thresholds FedEx applies to US domestic shipments.
What this means
FedEx computes DIM weight as length × width × height ÷ 139 (inches and pounds). Every fractional inch rounds UP to the next whole inch — 47.1 in becomes 48 in — and the result rounds up to the next whole pound. Billable weight is the greater of the rounded actual weight and the DIM weight.
FedEx surcharge diagnostics
The result below also checks FedEx's deterministic surcharge thresholds: Additional Handling applies when the longest side exceeds 48 in, the second-longest side exceeds 30 in, length + girth exceeds 105 in, or cubic volume exceeds 10,368 in³ (new in January 2026). Packages triggering Additional Handling–Dimension carry a 40-lb minimum billable weight. Oversize applies above 96 in length, 130 in length + girth, 17,280 in³, or 110 lb. Ground packages over the maximum limits (108 in / 165 in / 150 lb) incur the Unauthorized Package Charge with a 90-lb minimum billable weight.
Worked example
24 × 18 × 12 in = 5,184 in³ ÷ 139 = 37.3 → 38 lb DIM weight. At 8 lb actual weight, FedEx bills 38 lb (+375%). Shrink the box to 20 × 16 × 10 in and the same package bills 24 lb.
Potential action
If DIM weight is driving the bill, use the box size optimizer. If the package is near a surcharge threshold, the surcharge checker shows how far each threshold is.
Official sources
What changed recently — and when it took effect
FedEx rules moved twice in the last two years. Since August 18, 2025, every dimension rounds up to the next whole inch (or centimeter) — FedEx previously rounded to the nearest. On January 12, 2026, Additional Handling gained its 10,368 in³ volume trigger and Oversize gained its 17,280 in³ and 110 lb triggers; since the same date, only the highest of Additional Handling, Oversize, and the Unauthorized Package charge applies. The FedEx surcharge guide walks through every trigger with worked examples, and the 2026 rule changes guide covers what moved at every carrier.
Related tools
Frequently asked questions
Why does the FedEx calculator divide by 139?
139 is the current FedEx US domestic DIM divisor: the cubic inches of space FedEx treats as one pound (the metric equivalent is 5,000 cm³/kg). A 24 × 18 × 12 in box is 5,184 in³, and 5,184 ÷ 139 = 37.3, rounded up to 38 lb of DIM weight. The lower the divisor, the more billable weight the same box produces — which is why the FedEx number often exceeds the UPS Retail number for an identical package.
Does FedEx round my measurements up?
Yes. Since August 18, 2025, FedEx rounds every dimension up to the next whole inch (or whole centimeter) before multiplying — 47.1 in bills as 48 in — and the final DIM weight rounds up to the next whole pound. The calculator applies both steps, so a label measured to the fraction will not surprise you at billing time.
What happens when my box is longer than 48 inches?
Longest side over 48 in is one of four Additional Handling triggers (the others: second-longest over 30 in, length + girth over 105 in, volume over 10,368 in³). A package triggering Additional Handling — Dimension bills at no less than 40 lb. Above 96 in the charge escalates to Oversize, and Ground packages over 108 in, 165 in length + girth, or 150 lb incur the Unauthorized Package charge with a 90-lb minimum billable weight. Only the highest of the three charges applies.