There's no single cheapest carrier. The cheapest option depends almost entirely on two numbers: how much your box weighs, and how big it is. Get those right and you can often cut the price in half.
Rule of thumb by weight
| Box | Usually cheapest | Why |
|---|---|---|
| Under 4 lb (small gifts, documents) | USPS First-Class Package International | Low base price; 4 lb is its limit |
| 4–10 lb, compact and heavy | USPS Priority Mail International Flat Rate box | One price regardless of weight, if it fits |
| 10 lb and up | Consolidated shipping by the pound | Cost is shared across many parcels on one shipment |
| Urgent, any weight | DHL Express / FedEx | You pay for speed, not savings |
The hidden cost: dimensional weight
Express carriers don't just weigh your box. They also calculate a "dimensional weight" from its size and charge whichever is higher. For most express services the formula is:
length × width × height (inches) ÷ 139
Example: an 18×18×18 inch box of pillows and clothes weighs 12 lb on the scale. Its dimensional weight is 18×18×18 ÷ 139 = 42 lb. You'd pay for 42 lb, not 12.
That's why a big, light box is the most expensive thing you can ship by express, and why consolidated shipping or a smaller box often wins.
7 ways to pay less
- Use the smallest box that fits. Every inch counts toward dimensional weight. We can repack your items into a better-sized box.
- Vacuum-bag soft items. Clothes, blankets and pillows shrink to a third of their volume.
- Combine shipments. One 30 lb box costs much less than three 10 lb boxes.
- Don't pay for speed you don't need. Express can cost several times more than consolidated cargo for the same box.
- Remove retail packaging. Shoe boxes and big product boxes add size for nothing.
- Stay under the customs limit. Splitting a large shipment, or not, can change what the recipient pays in duty. See duty-free limits for 2026.
- Compare at the counter. We check USPS, FedEx, DHL and consolidated rates for your exact box and show you the options.
What about package forwarders?
If you're abroad and buying from US stores, a forwarding address can save a lot by combining several orders into one box. We explain how in shop in the USA and ship abroad.
Get an exact price
Use the KaspiPost calculator for per-pound rates, or bring the box to our store at 7300 W Sunset Blvd in Los Angeles. We weigh it, measure it and give you the price before you pay.
Frequently asked questions
What is the cheapest way to ship a package internationally?
For under 4 lb, usually USPS First-Class Package International. For heavier boxes, consolidated shipping charged by the pound is usually cheapest. Express couriers are the most expensive option.
Is USPS cheaper than FedEx or DHL for international shipping?
For small and light parcels, usually yes. For heavy boxes, consolidated shipping often beats both. DHL and FedEx are faster but cost more.
How do I calculate dimensional weight?
Multiply length × width × height in inches and divide by 139 (the divisor most express carriers use). If the result is higher than the actual weight, that's what you pay for.
What's the cheapest way to ship a 20 lb box overseas?
In most cases, consolidated shipping by the pound. A 20 lb box sent by express can cost several times more.
Customs and carrier rules change often. This article is accurate as of the date above — check with us before you ship.