In three ordered steps: the carrier settles your billable weight, finds the zone your two ZIP codes define, then reads the price from the chart of whichever speed tier you chose. Optional add-ons stack afterward. Every step below is demonstrated with a live quote pair from 2026-07-27, so you can watch the formula work instead of taking it on faith.
Weight, zone, tier. Once you see each input priced alone, quotes stop feeling arbitrary.
Carriers weigh your box twice, once on a scale and once with a tape measure, and bill the bigger answer. To catch it in the act we quoted 6 lb of household goods in two different cartons on the Newark, NJ 07102 to Atlanta, GA 30303 route.
| Carton | Scale weight | Cheapest quote |
|---|---|---|
| 14 x 10 x 6 in | 6 lb | $13.51 UPS Ground Saver |
| 24 x 18 x 16 in | 6 lb | $40.28 UPS Ground |
The scale never changed; the tape measure tripled the bill. The formula behind that, and a tool that runs it on your numbers, live on our dimensional weight calculator page, so we won't repeat the math here.
With billable weight fixed, the ZIP pair picks a column in the rate chart. Here is one small box, 2 lb on the scale, quoted the same day on two lanes of very different length.
| Lane | Quote |
|---|---|
| Newark, NJ 07102 to Atlanta, GA 30303 | $8.48 |
| Los Angeles, CA 90011 to New York, NY 10001 | $11.04 |
At 10 lb the zone gap widens: $20.86 east against $30.09 west for the equivalent box in the same capture. Distance costs more per pound as the pounds accumulate, which surprises almost everyone the first time they ship something heavy across the country.
Weight and zone now fixed, the remaining lever is urgency. These are all five options our calculator returned for a single 1 lb box from Newark to Atlanta, slowest to fastest.
| Service | Price | Quoted window |
|---|---|---|
| USPS Ground Advantage | $9.91 | 6-7 business days |
| UPS Ground | $10.31 | 3-4 business days |
| USPS Priority Mail | $14.49 | 4-5 business days |
| UPS 3 Day Select | $15.13 | 3-4 business days |
| UPS 2nd Day Air | $16.58 | 2-3 business days |
Notice the ordering isn't clean: the second-cheapest row was also among the fastest, and a pricier tier quoted a slower window than the one below it. Tier charts come from different networks with different geography, so reading the whole list beats assuming money buys speed linearly.
Rate charts move in whole-pound brackets, so a package gets billed at the top of its bracket regardless of ounces. That's why our data shows plateaus where two weights price identically and cliffs where one more pound jumps the total. Weigh the packed box, not the bare item.
Coverage fees, signature collection, and similar options are flat charges stacked onto the computed rate, each one published in the carrier's fee schedule. They never change the base math; they just ride on it. Price the base first, then decide which riders the shipment deserves.
When a quoted price and a final bill disagree, the culprit is almost always a box that measured bigger or heavier at the depot than at home. Carriers re-measure automatically. Honest dimensions at quote time, with the padding included, is the entire defense.
The number the carrier charges on, which is the larger of two candidates: what your package weighs on a scale, and what its outer dimensions say it ought to weigh. A big airy box loses that contest, which is how our 24 by 18 by 16 inch shipment ended up billed far above its 6 lb of contents.
A distance band between origin and destination ZIP codes. Every rate chart is organized by weight down one side and zone across the top, so the same parcel gets a different cell, and a different price, depending on how far apart the two addresses sit. Our 2 lb test box demonstrated it: $8.48 on the shorter eastern lane, $11.04 coast to coast.
Whichever is worse for you, by design. Dense compact packages are priced off the scale; light bulky ones are priced off their volume. The break-even lives in the size-to-weight ratio, and our dimensional weight page has a tool that finds it for your exact box in seconds.
All of them. Describe the item, and the calculator estimates the packed box, applies the billable-weight comparison, resolves the zone from your two ZIP codes, and brings back live tiers from USPS, UPS and FedEx with the totals checkout will actually collect.