Plenty of tools will estimate a USPS price. This one returns rows you can buy: the calculator quotes your exact box, and the Ground Advantage or Priority Mail figure it shows is the figure the checkout charges. The tables below are its actual USPS output from 2026-07-27, so you can see the shape of the pricing before you type anything.
Ten box sizes fed through production on 2026-07-27; the USPS rows landed here untouched.
We quoted one carton at ten weights on each coast and kept only the USPS lines. A dash means USPS didn't crack the strongest five options at that weight, which on these lanes starts happening once boxes get heavy. If you came for an explanation of USPS pricing rather than a tool to run it with, our companion article on what USPS charges to ship a package walks the same data with commentary.
| Packed weight | Ground Advantage | Window | Priority Mail | Window |
|---|---|---|---|---|
| 1 lb | $9.91 | 6-7 business days | $14.49 | 4-5 business days |
| 2 lb | $8.48 | 6-7 business days | – | – |
| 3 lb | $8.48 | 6-7 business days | – | – |
| 5 lb | $14.67 | 6-7 business days | – | – |
| 10 lb | $20.86 | 6-7 business days | – | – |
| 15 lb | $23.69 | 6-7 business days | – | – |
| 20-50 lb | – | – | – | – |
| Packed weight | Ground Advantage | Window | Priority Mail | Window |
|---|---|---|---|---|
| 1 lb | $11.12 | 6-7 business days | $16.47 | 2-3 business days |
| 2 lb | $11.04 | 6-7 business days | $22.34 | 2-3 business days |
| 3 lb | $11.04 | 6-7 business days | $22.34 | 2-3 business days |
| 5 lb | $20.84 | 6-7 business days | $32.26 | 2-3 business days |
| 10 lb | $30.09 | 6-7 business days | – | – |
| 15 lb | $35.33 | 6-7 business days | – | – |
| 20 lb | $55.71 | 6-7 business days | – | – |
Two things jump out of the raw rows. Identical prices at 2 and 3 lb on both coasts show USPS billing in bands rather than per ounce at this size. And the cross-country Priority Mail lines pair a 2-3 day window with a price that climbs fast, which is the whole USPS trade in miniature: Ground Advantage for patience, Priority for the calendar.
usps.com lists Ground Advantage from $7.90 and Priority Mail from $11.00 at a Post Office (checked 2026-07-27), and those anchors are honest as far as they go. A starting price just isn't your price. The calculator's rows already contain the ZIP pair, the packed box and SMKlog's charge, so the number survives contact with checkout.
Per USPS Notice 123 (retrieved 2026-07-27), a Priority Mail flat rate envelope runs $12.90 retail, a medium box $24.80 and a large $34.00. Dense little shipments sometimes beat our quoted rows with those, so compare before committing either way.
From 20 lb up on the Newark lane, no USPS line survived into the strongest five; UPS and FedEx ground tiers owned the heavy boxes. Seeing the absence is useful in itself, and it's the kind of gap a single-carrier tool never shows you.
Ground Advantage showed up on nearly every lane we captured, Priority Mail on many, and Priority Mail Express where it earned a slot; the only Express rows in our 2026-07-27 data were Puerto Rico lanes, at $103.46 from Newark. Media Mail never appeared, since eligibility depends on contents we can't see.
A Post Office counter quotes retail off its own scale, and usps.com lists Ground Advantage starting at $7.90 retail (checked 2026-07-27). Our rows are the checkout total for one defined packed box on one ZIP pair, carrier label and SMKlog's charge together, with nothing bolted on later.
No. Type what the item is and the calculator estimates the packed box for you, then shows live USPS rows against UPS and FedEx. Confirm the dimensions look sane before buying, because the label is priced on the box you approve.
Every table row was captured on 2026-07-27 on the two routes named above it. Carriers refile rates often enough that a dated table is a reference point, not a promise, so run the lane fresh when you're ready to ship.