Four inches by six is the layout the Postal Service recommends for parcels, and every scanner, roll of label stock and shipping app in the country was built around that choice. Two smaller formats are documented for awkward parcels, but if you buy one kind of stock, buy this one.
This page is about the media and the machine settings rather than the measurements themselves. What to feed a printer, what a letter sheet can do instead, and the one dialog option that quietly ruins a barcode.
Roll, sheet or plain paper. The printed area is identical in all three cases.
The Postal Service is unambiguous about it. Quoting the Parcel Labeling Guide, version 3 release 5, read on postalpro.usps.com on 2026-07-28: the 4x6 label “is the USPS recommended layout for parcel labels” and “allows for optimum spacing of all elements and still allows space for additional information and user elements to be defined by the mailer”.
The same document explains where the space goes. The payment and branding strip runs roughly 1 5/16 inches tall, the barcode segment about 1 1/2 inches, and the delivery address block gets an area of roughly 3 3/20 by 1 5/16 inches including margins. Add those up and a smaller rectangle stops being comfortable, which is precisely what the two alternate formats acknowledge.
Neither alternative is worth stocking for a household or a small shop. Buy 4 by 6 and use it for everything.
One rule outranks all three choices. Whatever the media, the barcode “must be printed on a substrate which is uniform in color”, so anything tinted, patterned or glossy is out regardless of how convenient the pack looked.
Every print dialog offers to fit the page for you, and every one of them is wrong here. Scaling a 4 by 6 label down by even a few percent thins the bars and the gaps together, and the guide requires a clear zone of at least 1/8 inch above and below the barcode where “No text, images, or other markings may appear”. A shrunk label can push a neighbouring element into that zone without looking any different to you.
Set scale to 100 percent or actual size, print one label, and lay a ruler across it. Four inches wide means you are done; anything less means the setting reverted, which some drivers do quietly after an update. On a thermal printer, check the stock size selected in the driver matches the roll you loaded, since a mismatch produces the same shrunken result from a different direction.
The label format is fixed; the price under it is not. Here is one small dense carton at four weights, quoted on 2026-07-28 from Newark, NJ 07102 to Atlanta, GA 30303, showing something most weight tables hide.
| Weight | USPS Ground Advantage | UPS Ground Saver | UPS Ground |
|---|---|---|---|
| 2 lb | $8.48 | $10.18 | $10.67 |
| 5 lb | $10.39 | $10.18 | $10.67 |
| 10 lb | $10.39 | $10.17 | $12.56 |
| 20 lb | $10.39 | $10.17 | $12.56 |
Look down the first two columns. Between 5 lb and 20 lb the price barely twitched, a single cent separating the Ground Saver rows, because a box this small is already priced on the space it occupies rather than on what it holds. Doubling the contents of a small dense carton twice over cost nothing at all on two of the three services.
Because the Postal Service recommends that layout and everything downstream was built around it. The Parcel Labeling Guide states that the 4x6 label is the USPS recommended layout for parcel labels and that it allows optimum spacing of all elements, per postalpro.usps.com read 2026-07-28.
USPS documents two smaller layouts. The 4x4 allows for less information than the 4x6 label but may be a useful format when shipping smaller sized parcels, and the 6x3 may be a useful format when shipping unusually shaped mailpieces such as mailing tubes. Both come from the same Parcel Labeling Guide.
For a thermal printer, 4 by 6 direct thermal rolls or fanfold stacks. For an ordinary home printer, either self-adhesive sheets that split a letter sheet into peel-off labels, or plain copier paper you trim and tape. All three end up as the same 4 by 6 printed area.
The print dialog scaled it. Fit to printable area shrinks the whole label by a few percent, which thins the barcode bars and the gaps between them at the same time. Choose actual size, print one, and measure it across with a ruler before you commit a box of stock.