USPS size limit checker
Enter your package and pick a service. USPS limits differ by service, so a blanket USPS maximum would be wrong — this checks against the service you are actually using.
How USPS size limits work
USPS caps two things for most parcels: the weight, and the length plus girth. There is no separate maximum on the longest side for the services we hold rules for — length plus girth is the measurement that catches long boxes, and our result says so rather than implying we checked something we did not.
- The general parcel weight maximum is 70 lb.
- Most mailpieces are capped at 108 in of length plus girth.
- Ground Advantage Retail allows up to 130 in, which is why the service matters.
Worked example
A 60 × 20 × 10 in box weighing 10 lb.
- Length plus girth is 60 + 2(20) + 2(10) = 120 in.
- That is over the 108 in general cap, so most USPS services refuse it.
- Ground Advantage allows 130 in, so it is accepted there.
- Same box, same weight, different answer — entirely because of the service.
Edge cases worth knowing
- There is no single "USPS maximum". Anyone quoting one without a service is glossing over the part that decides your answer.
- Length plus girth, not length. A 40 in box can fail while a 60 in box passes, if the 40 in one is fat and the 60 in one is thin.
- Weigh it packed. The carrier weighs what arrives, including tape, padding, and the box itself.
- Being inside the limit is not the whole cost story. Dimensional weight can still bill you for a large light box.
Common questions
- What is the maximum package size for USPS?
- It depends on the service. Most mailpieces cap at 108 in length plus girth; Ground Advantage Retail goes to 130 in. The weight maximum for general parcels is 70 lb.
- Why does this not check my longest side?
- Because we hold no standalone maximum-length rule for USPS — the constraint is on length plus girth. We say what we did not check rather than quietly passing it.
- My box is over. What are my options?
- A squarer box with the same volume has a lower length plus girth. Failing that, Ground Advantage allows more, or split the shipment.