If you ask Google "is FedEx or UPS cheaper for DIM weight," you'll get a hundred articles answering "it depends." Here's the honest version: the divisor itself is identical for most shippers, so the price difference comes from somewhere else entirely.
The divisor math is the same
For commercial account holders — the vast majority of business shippers — both FedEx and UPS apply a divisor of 139 cubic inches per pound (or 5000 cm³/kg metric) to almost every service tier. If you ship the exact same package on both, the DIM weight calculation produces the exact same number.
That means for the example below — a 24×18×12 inch box weighing 8 pounds:
Identical. Both carriers bill 38 pounds, not 8. So if the math is the same, where does the price difference actually come from?
Three places the real difference lives
1. Base rate per pound
FedEx and UPS publish slightly different rate cards. UPS Daily Rates tend to be marginally cheaper for Ground in most US zones; FedEx Express tends to be marginally cheaper for cross-country overnight. The differences are often a dollar or two per shipment — small, but real when you ship 1,000 packages a month.
2. Fuel surcharge
Both carriers add a fuel surcharge that updates weekly and varies between them. As of mid-2026, the surcharges typically differ by 1–3 percentage points. That's a meaningful spread on a $20 shipment.
3. Which divisor you actually qualify for
This is the big one. UPS uses the friendlier 166 divisor for Retail Rates (walk-in customers without an account). FedEx applies its Ground Retail rate at 166 as well. So if you're shipping without an account, both are equivalent. But if you have an account, both drop you to 139 — which is significantly more expensive on DIM weight.
Negotiated rates are where the real money is. Large commercial shippers can negotiate custom divisors with both FedEx and UPS — sometimes as high as 150 or 160. A 5-point difference in divisor on a 5,000-package monthly volume is thousands of dollars saved.
The honest answer
For a given package, the DIM weight will be identical between FedEx and UPS at standard rates. The actual price difference comes from base rates, fuel surcharges, accessorials (residential delivery, fuel, signature), and any negotiated discounts you've layered on top.
If you ship enough volume to negotiate rates, both carriers will compete hard for your business — and you should run rate quotes with both before committing.
For everyone else: use the calculator above to find your billable weight, then run actual rate quotes on FedEx and UPS with the same package to compare real-dollar prices.
The exception: UPS Retail vs FedEx Retail
UPS Store walk-in customers use the 166 divisor (more favorable). FedEx Office walk-in customers use 139. So for occasional shippers without a business account, UPS Retail is mathematically cheaper on the DIM weight portion.
This rarely matters in practice because retail customers usually ship infrequently and small packages where DIM weight may not even apply.
Run the calculation
Use the dimensional weight calculator to see exactly what your package would bill at across every major carrier.
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