Both networks were asked to price identical boxes on one morning, once into the Midwest and once across to the desert Southwest. USPS undercut FedEx on every light carton. FedEx took the lead as the weight climbed, and on the longer haul it took the lead sooner. The figures below are what checkout collects, carrier postage and SMKlog's charge in one number, captured 2026-07-29.
Between 10 and 20 lb on the short lane. Between 4 and 10 lb on the long one.
Each request went out with one carton and came back with the five least expensive rates available for it. The columns below pull out the cheapest postal row and the cheapest FedEx row from each of those answers, so the comparison is like for like on the same box, the same day and the same address pair.
| Carton | USPS | FedEx | Lower price |
|---|---|---|---|
| 10 × 7 × 4 in 1 lb | $9.47 USPS Ground Advantage, 4-5 business days | no FedEx row among the five returned | USPS |
| 12 × 10 × 6 in 4 lb | $8.42 USPS Ground Advantage, 4-5 business days | $11.78 FedEx Ground Economy, 5-6 business days | USPS |
| 16 × 12 × 9 in 10 lb | $13.88 USPS Ground Advantage, 4-5 business days | $16.31 FedEx Ground Economy, 5-6 business days | USPS |
| 18 × 14 × 12 in 20 lb | $28.06 USPS Ground Advantage, 4-5 business days | $19.70 FedEx Ground Economy, 5-6 business days | FedEx |
| 20 × 16 × 14 in 45 lb | no postal row among the five returned | $44.45 FedEx Ground Economy, 5-6 business days | FedEx |
The lead changes hands once, somewhere between the 10 lb carton and the 20 lb carton. Below that line the postal price is the one to beat; above it the postal price climbs faster than the FedEx price does, and at 45 lb no postal row made the shortlist at all. The faster FedEx tier turned up on that heavy carton too, at $49.30 for FedEx Ground with a 4-5 business day window.
Distance does not shift both carriers by the same amount, so the crossover is not a fixed weight. Running four of the five boxes out to Phoenix moved it down the ladder by a full step.
| Carton | USPS | FedEx | Lower price |
|---|---|---|---|
| 10 × 7 × 4 in 1 lb | $11.12 USPS Ground Advantage, 4-5 business days | no FedEx row among the five returned | USPS |
| 12 × 10 × 6 in 4 lb | $12.70 USPS Ground Advantage, 4-5 business days | $17.59 FedEx Ground Economy, 8-9 business days | USPS |
| 16 × 12 × 9 in 10 lb | $25.18 USPS Ground Advantage, 4-5 business days | $23.92 FedEx Ground Economy, 8-9 business days | FedEx |
| 18 × 14 × 12 in 20 lb | $55.71 USPS Ground Advantage, 4-5 business days | $35.03 FedEx Ground Economy, 8-9 business days | FedEx |
On the Ohio lane the postal service was still ahead at 10 lb. On the Arizona lane it had already fallen behind at that weight, and by 20 lb it was quoting more than half again what FedEx wanted. Anyone who has memorized a rule of thumb from one favorite lane should retest it on the route actually in front of them.
One more row from the Arizona capture is worth keeping: the faster FedEx tier, FedEx Ground, quoted $55.53 on that 20 lb carton with a 6-7 business day window. That sits eighteen cents under the postal price and arrives two business days later, which is the sort of near-tie that makes the delivery window the real tiebreaker rather than the number.
Quote your carton on your own lane Add UPS to the comparison
Every FedEx price that beat a postal price in these captures came from FedEx Ground Economy, the slowest tier FedEx sells for household parcels. Reading the two price columns without the two window columns gets the decision wrong.
USPS Ground Advantage came back at 4-5 business days on both lanes, every weight. FedEx Ground Economy came back at 5-6 business days into Ohio and 8-9 into Arizona. Same box, same day, four extra business days on the western run.
USPS lists Ground Advantage at 2 to 5 days and Priority Mail at 2 to 3 days (usps.com, read 2026-07-29). FedEx states that delivery within the contiguous U.S. takes 1 to 5 business days on its ground services (fedex.com, read 2026-07-29). Both quoted windows sat at the slow end of the published ranges.
FedEx publishes that FedEx Ground delivers to businesses Monday through Friday, while FedEx Home Delivery reaches residences every day of the week and carries a four-dollar residential surcharge per package. A Saturday arrival is normal for one and not offered by the other.
If the recipient is waiting on a birthday, an auction deadline or a return window, the postal row on these lanes bought two to four business days for a few dollars. If nobody is watching tracking, the economy tier is the cheaper way to move a heavy box and the wait costs nothing.
Price stops mattering the moment a box falls outside a carrier's envelope. These are the ceilings each carrier publishes for United States packages, read on 2026-07-29.
| Limit | USPS | FedEx |
|---|---|---|
| Heaviest package | 70 lbs, stated as the maximum for a USPS package | 150 lbs on the ground services |
| Longest side | not published as a separate figure; the size test is length plus girth | 108 in |
| Length plus girth | 130 in, or under 108 in for Priority Mail and Priority Mail Express | 165 in, measured as length plus twice the width plus twice the height |
| Where it stops being a package | above 70 lbs there is no postal service to move it | heavier than 150 lbs, or a combined length and girth of more than 165 in, is handled as freight |
| Extra charge before the ceiling | additional fees may apply for dimensional weight or nonstandard size | an oversize charge applies past 96 in in length or 130 in in length or girth |
The gap between 70 and 150 lbs is the part worth remembering. Anything in that band is not a postal shipment at any price, which is why the 45 lb carton earlier still had a postal option on paper while a 90 lb one would not. Past 150 lbs, or past 165 inches of length and girth, FedEx itself stops calling the shipment a package, and the box belongs on a pallet.
Under about 10 lb the postal network was cheaper on both lanes tested and quicker on both. Small dense parcels are what that network was built around, and nothing in this capture argued otherwise.
Above 20 lb the FedEx economy tier led on both lanes, and past 70 lbs FedEx is the only one of the two still in the running. Volume rather than mass is often what pushes a box across that line.
The crossover weight fell by a step when the destination changed from Ohio to Arizona. Quote the actual origin and destination rather than trusting a threshold somebody worked out on a different route.
Our calculator asks both carriers at once, along with UPS, and lists every rate that came back with its price and its window. Guest checkout, printable label, tracking attached. Shipping protection is offered during checkout where the carrier supports it for the route.
It flips with weight. In the 2026-07-29 quotes on this page USPS was under FedEx at 1, 4 and 10 lb going to Ohio, and FedEx was under USPS at 20 and 45 lb. On the longer run to Arizona the flip happened between 4 and 10 lb instead.
Because the FedEx rows that undercut USPS were FedEx Ground Economy, the slowest tier. It quoted 5 to 6 business days into Ohio and 8 to 9 into Arizona, against 4 to 5 business days for USPS Ground Advantage on both lanes.
USPS states that the maximum weight for a USPS package is 70 lbs. FedEx states that packages up to 150 lbs. can be shipped on its ground services. Both figures were read from the carriers' own pages on 2026-07-29, and they mean anything between those two numbers is a FedEx question, not a postal one.
FedEx publishes that FedEx Ground delivers to businesses Monday through Friday while FedEx Home Delivery delivers to residences every day of the week, and that a four-dollar residential surcharge is added per package on Home Delivery. Read from fedex.com on 2026-07-29.
Each quote returns the five least expensive rates it found. On the 1 lb carton those five slots were taken by postal and UPS services, so no FedEx row appeared. That is a ranking outcome, not a refusal.
Carriers refile prices and rewrite these pages without warning, and a single capture is a photograph rather than a rule. The tables above are what two networks answered for those exact cartons on 2026-07-29. Quote the box in your hands.