Size surcharges are some of the most expensive lines on a carrier invoice, and they’re entirely predictable from your box dimensions — every one of them is measured from the longest side and the length plus girth. This guide lists the thresholds carriers publish, checked against their own documents on 22 September 2026, and the packaging changes that keep you under them.
How carriers measure size
Two measurements matter: the longest side (the “length”) and length plus girth:
Length + girth = Length + 2 × (Width + Height)
Measure the packed box, and assume fractions round up to the next whole inch — FedEx, UPS and USPS all instruct this.
UPS thresholds (US domestic)
From the UPS 2026 Rate and Service Guide (Daily Rates, pp. 179–181):
| Line | What happens | 2026 charge |
|---|---|---|
| Longest side over 48 in (122 cm), second-longest over 30 in (76 cm), length + girth over 105 in (267 cm), or cubic size over 10,368 in³ | Additional Handling; 40 lb minimum billable weight | $30.00–$40.50 |
| Actual weight over 50 lb (55 lb international) | Additional Handling | $46.50–$58.75 |
| Not in corrugated cardboard, cylindrical, banded, soft pack over 18 × 14 × 6 in, or 1 in or less in height | Additional Handling | $26.75–$33.75 |
| Length + girth over 130 in (330 cm), length over 96 in (244 cm), weight over 110 lb, or cubic size over 17,280 in³ | Large Package; 90 lb minimum billable weight (no Additional Handling charged on top) | $219.50–$286.00 commercial; $254.50–$331.00 residential |
| Over 150 lb, over 108 in long, or over 165 in length + girth | Over Maximum Limits — not accepted | $1,875.00 |
The minimums are what make these lines so expensive for light items: a 5 lb box that crosses the 48 in line is billed at 40 lb, and one that crosses 130 in of length plus girth is billed at 90 lb — before the surcharge itself.
USPS limits
USPS doesn’t publish an “oversize” surcharge for these services; it has hard limits (USPS DMM 101):
- Priority Mail and Priority Mail Express: up to 108 in length plus girth and 70 lb.
- USPS Ground Advantage: up to 108 in length plus girth and 70 lb; only Ground Advantage – Retail (bought at the counter) allows up to 130 in (USPS DMM 101 §3.2.1).
Dimensional weight applies to USPS parcels over 1 ft³, at a 139 divisor (DMM 223 §1.4).
FedEx
FedEx’s thresholds for US package services, from the FedEx Service Guide 2026 (pp. 127–129):
| Line | What happens | 2026 charge |
|---|---|---|
| Longest side over 48 in, second-longest over 30 in, length + girth over 105 in, or over 10,368 in³ | Additional Handling — dimension; 40 lb minimum billable weight | $29.50–$40.75 |
| Actual weight over 50 lb (55 lb international) | Additional Handling — weight | $46.00–$58.75 |
| Not in a corrugated box, cylindrical, banded, or oversized soft pack | Additional Handling — packaging | $26.50–$33.75 |
| Longest side over 96 in, length + girth over 130 in, over 17,280 in³, or over 110 lb | Oversize; 90 lb minimum billable weight (US) | $255–$330 |
| Over 108 in long, over 165 in length + girth, or over 150 lb | Unauthorized — may be refused | $1,875 (Ground) |
Charges vary by zone. FedEx’s size lines are the same as UPS’s — including the 105 in length + girth line and the 40 lb minimum. The packaging rules differ slightly: FedEx’s soft-pack limit is 18 × 13 × 5 in, UPS’s is 18 × 14 × 6 in.
Worked example
A 40 × 20 × 20 in box: length + girth = 40 + 2 × (20 + 20) = 120 in. That’s under UPS’s 130 in Large Package line, but the cubic size is 16,000 in³ — over the 10,368 in³ Additional Handling line. Cutting the box to 36 × 18 × 16 in gives 10,368 in³ exactly, which is not over the line, and L+G of 104 in.
How to design boxes that stay under the lines
1. Know which line you’re fighting
Long, thin items hit the longest-side lines (48 and 96 in at both UPS and FedEx). Big, boxy items hit cubic size and length plus girth. The fix is different for each, so check all of them.
2. For length plus girth, don’t default to a cube
Width and height count twice in length plus girth; length counts once. For a fixed volume, length plus girth is smallest when the length is about twice the width and height. A 2,000 in³ cube (12.6 in per side) has L+G of 63 in; a 20 × 10 × 10 in box with the same volume has 60 in.
3. Avoid fractional inches
Because fractions round up, a box that measures 48.2 inches is treated as 49 — over the 48 in line. Specify boxes in whole inches with a margin.
4. Split the shipment
If a product can ship in parts, two packages under the lines are often cheaper than one package over them. Compare both against your rates.
What if you can’t avoid it?
- Over the parcel maximum: anything over UPS’s 150 lb / 108 in / 165 in limits needs freight.
- Frequent oversize shipments: surcharges are negotiable in many carrier contracts; bring your volume data to the conversation.
The bottom line
Oversize fees are predictable from box dimensions. If a meaningful share of your packages crosses these lines, redesigning a few box sizes is one of the highest-return changes you can make.