Girth Calculator
Girth, length plus girth, and whether the carrier will actually take the box.
Length + girth
100.0 in
- Length (the longest side)
- 30.0 in
- Girth — 2 × (20.0 + 15.0)
- 70.0 in
- Volume
- 9,000 in³ (5.21 ft³)
- Dimensional weight at 1:139
- 65 lb
- Billable weight
- 65 lb — billed on dimensions
- Density
- 4.8 lb/ft³
Carriers remeasure at the terminal. A correction arrives as a billing adjustment weeks after delivery.
UPS Ground: within the standard parcel envelope
Limits are 108 in length, 165 in combined and 150 lb, with the surcharge starting at 130 in combined.
Shipping cartons by sea or air instead? Work out CBM and chargeable weight →
How this is calculated
length = the longest of the three sides girth = 2 × (the other two sides added) combined = length + girth dim wt = length × width × height ÷ divisor, rounded up billable = the greater of scale weight and dim weight
The sides are sorted before anything else happens, which is the whole trick. Girth is the tape measure going around the parcel at its thickest point, so it can only ever be twice the two smaller dimensions. Feed the sides in any order you like — the answer does not move. Nearly every disagreement between a homemade figure and a carrier's figure comes from including the longest side in the girth.
The combined figure exists because volume alone does not describe handling. A 10-foot tube and a 3-foot cube can hold the same air and need completely different equipment to move. One limit written as length plus girth catches the long thin parcel and the fat one at the same time, which is why every parcel carrier in the world uses some version of it.
Where the limits sit
| Carrier | Max length | Max L + girth | Max weight | Surcharge from | Divisor |
|---|---|---|---|---|---|
| UPS Ground | 108 in | 165 in | 150 lb | 130 in | 1:139 |
| FedEx Ground | 108 in | 165 in | 150 lb | 130 in | 1:139 |
| USPS Ground Advantage | 108 in | 130 in | 70 lb | 108 in | 1:166 |
Read the surcharge column before the maximum one. Between those two figures the parcel still ships, but a large-package charge applies and it usually comes with a minimum billable weight of its own — so a 40-pound oversized box can be invoiced at 90. That fee is frequently larger than the shipping it is attached to, and it is the reason splitting a shipment into two ordinary boxes so often beats sending one big one.
The USPS row is the one to watch for a small business. Its combined limit of 130 inches and its 70-pound ceiling are both well under the private carriers, and the weight limit catches people far more often than the size limit — a compact, dense box can be perfectly ordinary for UPS and refused at the post office counter.
What the same volume looks like in different shapes
| Parcel | Girth | Length + girth | Volume | UPS Ground |
|---|---|---|---|---|
| 24 × 18 × 18 in | 72 in | 96 in | 4.5 ft³ | Standard |
| 36 × 18 × 18 in | 72 in | 108 in | 6.8 ft³ | Standard |
| 60 × 12 × 12 in | 48 in | 108 in | 5.0 ft³ | Standard |
| 96 × 10 × 10 in | 40 in | 136 in | 5.6 ft³ | Surcharge |
| 48 × 30 × 24 in | 108 in | 156 in | 20.0 ft³ | Surcharge |
The fourth row is the instructive one. A 96 × 10 × 10 parcel holds under six cubic feet — less than the first row — and still lands in surcharge territory, because length plus girth punishes length twice as hard as it punishes bulk. If a shipment can be repacked shorter and fatter for the same volume, that is almost always the cheaper shape.
Frequently asked questions
How do you calculate girth?
Measure all three sides, set the longest one aside as the length, then add the other two together and double the result. That is girth: the distance a tape measure travels around the parcel at its thickest point, which is twice the width plus twice the height. The longest side is never part of it, and getting that backwards is the most common reason a calculated figure and a carrier's figure disagree.
What is length plus girth?
It is the single number carriers use to size a parcel, written as L + 2(W + H). It exists because neither length nor volume alone describes how awkward a box is to handle on a conveyor. A long thin tube and a large cube can hold the same volume while needing entirely different equipment, so the combined figure catches both shapes with one limit.
What are the UPS and FedEx size limits?
Both take ground parcels up to 108 inches long, up to 165 inches in length plus girth, and up to 150 pounds. Above 130 inches combined — or above a length that varies by service — the parcel is still accepted but carries a large-package surcharge, which is usually the single largest line on the label. Past 165 inches combined it stops being a parcel and has to move as freight.
What is the USPS limit?
USPS Ground Advantage and Priority Mail take 130 inches in combined length and girth and 70 pounds, both well below the private carriers. Anything over 108 inches combined is charged as an oversized parcel. The lower weight ceiling catches people out more often than the size one: a compact but heavy box can be fine for UPS and refused by USPS at the counter.
Why is my parcel billed at more than it weighs?
Because a truck runs out of space before it runs out of payload, so carriers bill on whichever is greater — the scale weight or a weight derived from the volume. Multiply the three sides, divide by the divisor on your rate card, and round up. Domestic UPS and FedEx use 139 cubic inches per pound; USPS uses 166 and only applies it to larger parcels going further.
Do I measure the box or what is inside it?
The box, at its widest points, after it is packed and sealed. Carriers measure the shipment as it arrives, so a bulging side, a handle, a pallet foot or anything taped to the outside is part of the dimensions whether or not you counted it. Rounding a measurement down to make a limit is a false economy: the terminal remeasures, and the correction arrives as a billing adjustment weeks later.
What happens if I go over the limit?
It depends how far over. Between the surcharge threshold and the maximum, the parcel ships and costs considerably more, often an extra flat fee plus a minimum billable weight. Past the maximum the carrier can refuse it, return it or reclassify it as freight at freight prices. If you are near the line, splitting the shipment into two boxes is almost always cheaper than one oversized one.
Size limits and dimensional divisors are contractual and change with each annual rate card. The figures here are the common published values for US domestic ground service and are starting points, not guarantees. Confirm the limits for your service level and account, and measure the packed parcel rather than the empty box.