What counts as a large package?
Practically, anything past about 24 inches on the long side or past 30 lb. Carriers add oversize charges past 130 inches in length plus girth and refuse parcels past 165 inches or 150 lb.
Large parcels
What is the cheapest way to ship a large package?
Large boxes are priced on their size, not their weight, and the carrier that wins small parcels usually does not quote at all. Four real cartons, all three carriers. Everything in the tables below was quoted through the SMKlog calculator on 2026-07-24. The prices are all-in — the carrier label plus what SMKlog charges — and nothing is added at checkout.
Live parcel ratesReal quotes, datedTracking included
Every number here is a real quote
Prices on this page came out of the SMKlog calculator on 2026-07-24 for the exact boxes and routes listed. Run yours for today's rate.
Four large cartons
| Box and weight | USPS | UPS | FedEx | Cheapest |
|---|---|---|---|---|
| 24 × 18 × 18 in, 30 lb | not offered | $43.77 Ground | $57.23 Smart Post | $43.77 UPS Ground |
| 30 × 20 × 20 in, 40 lb | not offered | $77.56 Ground | $96.47 Smart Post | $77.56 UPS Ground |
| 36 × 24 × 18 in, 50 lb | not offered | $95.62 Ground | $118.87 Smart Post | $95.62 UPS Ground |
| 48 × 24 × 12 in, 35 lb | not offered | $86.45 Ground | $108.49 Smart Post | $86.45 UPS Ground |
Large cartons are where the ground networks separate from the mail. USPS returned nothing on these boxes on this run, and the spread between the cheapest and the most expensive quote is bigger than the price of the small boxes entirely.
Why the price jumps
| Box | Actual weight | Dimensional weight (÷139) | Length + girth | Cheapest quote |
|---|---|---|---|---|
| 24 × 18 × 18 in | 30 lb | 55.9 lb | 96 in | $43.77 |
| 30 × 20 × 20 in | 40 lb | 86.3 lb | 110 in | $77.56 |
| 36 × 24 × 18 in | 50 lb | 111.9 lb | 120 in | $95.62 |
| 48 × 24 × 12 in | 35 lb | 99.5 lb | 120 in | $86.45 |
Every box above is billed on dimensional weight, not on the scale. That is the whole game with large parcels: an inch off each side is worth more than a pound out of the box.
Common questions
What is the cheapest way to ship a large package?
On this run UPS Ground was cheapest on all four large cartons, from $43.77 for a 24 × 18 × 18 in 30 lb box to $95.62 for a 36 × 24 × 18 in 50 lb box. USPS returned no rate for any of them.
Is it cheaper to send two smaller boxes?
Often yes. Two 20 lb boxes frequently beat one 40 lb box once dimensional weight and oversize charges are counted. Quote both ways before you tape anything shut.
When does it stop being a parcel and become freight?
Past 150 lb, past 108 inches in length, or when the item needs a pallet. SMKlog sends those to a freight review with a person instead of selling a parcel label that would be repriced or refused.
Does the carrier really measure my box?
Yes. Automated dimensioners scan parcels in the sort hubs, and an under-declared box comes back as a billing adjustment after delivery. Measuring the finished carton honestly costs nothing and removes the surprise.