Dimensions / Industrial & logistics / Shipping labels / 4 × 6 thermal label
A 4 × 6 shipping label is 4 in wide and 6 in tall, 101.6 × 152.4 mm. USPS calls it its preferred label size and recommended layout; UPS uses 4 × 6 or 4 × 8 in when the extended area is needed (its regular label is 4 × 4.25 in); FedEx prints it as Format 435 without a doc-tab and makes it 4 × 6.75 in with one. Desktop rolls hold 475 labels on a 1 in core (Uline, Labelident) and run on a 104 mm liner, so a 4-inch printer such as the Zebra ZD421 (104 mm print width at 203 dpi) prints it edge to edge. It is not A6 (105 × 148 mm), and 100 × 150 mm is a separate stock.
| Label: width × height (USPS preferred) | Same in mm | FedEx with doc-tab (Format 354) |
|---|---|---|
| 4 × 6in | 101.6 × 152.4mm | 4 × 6.75in |
Sources: USPS, Labelident, FedEx. Checked October 2026.
A USPS barcode, a carton and Labelident’s 475-label roll on a Zebra ZD421 are filled in. Enter your own; each check follows a rule or figure on this page.
The barcode runs across the label width. With quiet zones it is (11N + 66) narrowest bars wide (GS1 General Specifications): 176 for an SSCC, 264 for a 34-digit IMpb. The narrowest bar has to be a whole number of printer dots.
3 dots at 203 dpi make the narrowest bar 0.375 mm (14.76 mil), inside USPS’s 13–21 mil. With quiet zones the IMpb is 264 of those, 99 mm, within the 101.6 mm label.
A 34-digit USPS IMpb printed at 203 dpi with a 3-dot bar (0.375 mm, 14.76 mil) is filled in. At 4 dots the bars are 0.5 mm and the barcode needs 132 mm, more than the label.
With 20 mm clear all round, the 101.6 × 152.4 mm label needs a face of 141.6 × 192.4 mm; the 305 × 229 mm face has room.
A 12 × 9 in carton top (305 × 229 mm) and FedEx’s “at least 2cm from edges” are filled in. USPS wants the address side, or the largest side if none is marked.
The 104 mm liner fits the printer’s 108 mm media width and the 119 mm roll its 127 mm maximum. At 0.144 mm a turn, the roll holds about 473 labels.
Labelident’s 475-label roll on a Zebra ZD421. Its stated roll length works out to 0.144 mm a turn; Uline’s 475 on a 5 in roll implies a thicker stock.
Selling 4 × 6 labels or printers? Photograph the roll, mark the label, liner and core in SizeMarker and send it with your quote.
Mark a photo| Carrier or standard | What it says |
|---|---|
| USPSParcel Labeling Guide 3.4.2 | Preferred size is the shipping industry standard of 4x6 inches, 4 wide by 6 high, the recommended layout; 4x4 and 6x3 inch labels are also described |
| USPS returnsPublication 199 | Standard return label sizes are 4x6, 4x4 and 3x6 inches |
| UPSGuide to Labeling 2017, third-party copy | Regular labels 4" x 4.25"; 4"x 6" and 4"x 8" when the extended area is used |
| FedEx thermalShip API; Ship Manager 3300 | 4 × 6 without a doc-tab (Format 435); 4 × 6.75 with or without one (Format 354 has it); 4 × 8, 4 × 8.5, 4 × 9 and 4 × 10.5 |
| FedEx doc-tab stockFedEx Office | 4" wide in 6.75" and 9" lengths, tab included |
| FedEx plain paperShip API | 4 × 6 PNG labels not on peel-and-stick stock are rejected, plain paper included |
| GS1General Specifications R26 | 4 x 6 inch and A6 (105 mm x 148 mm) listed as separate sizes, both for an SSCC with limited data |
| GLS Denmark | Calls its Zebra label A6 but gives 4x6 inches or 101.6 x 152.4 mm |
| DHL PaketGermany | Its own thermal labels are 103 x 199 mm |
Sources: USPS · USPS · UPS · FedEx · FedEx · FedEx Office · GS1 · GLS · DHL Paket
| Roll | Labels; core | Roll size; liner; gap |
|---|---|---|
| Uline S-22378This page | 475; 1" core | 5" OD |
| Uline S-6264Industrial | 1,000; 3" core | Roll diameter (actual) 7 1/8" |
| Uline S-10774 | 2,450; 3" core | 12" diameter |
| Uline S-7901With 2" tab | 185 a roll | — |
| Labelident ERT-E102X152Z1-475101.6 x 152.4 mm | 475; 1 in (25.4 mm) | 119 mm across; 104 mm liner; 3.175 mm gap; 73.9 m of labels |
| FedEx Office, 1" core | 3,400 a carton of 8 rolls: 425 a roll (our division) | — |
| FedEx Office, 3" core | 5,550 a carton of 6 rolls: 925 a roll (our division) | — |
| Labelident ERT-E100X150Z1-P500Not 4 × 6 | 100 x 150 mm; 500; 1 in core | 103 mm liner; 2.4 mm gap |
Sources: Uline · Uline · Uline · Uline · Labelident · FedEx Office · Labelident
| Item | Figure |
|---|---|
| Zebra ZD421Desktop | Print width 104 mm at 203 dpi, 106 mm at 300 dpi; direct-thermal media 15 to 108 mm; roll up to 127 mm (5.00 in) |
| Zebra ZD4112-inch model | Prints 56 mm (2.2 in) at 203 dpi: too narrow for 4 × 6 |
| Zebra ZT411Industrial | Print width 104 mm; roll 203 mm on a 76 mm (3 in) core; gap 2 to 4 mm, preferably 3 mm |
| Brother QL-1100 | Max label width 102 mm (~4"); max print width 4 |
| DYMO LabelWriter 5XLOffice Depot listing | Maximum print width 105.73; works only with DYMO labels |
| Dot pitchZebra | 0.125 mm at 203 dpi, 0.085 mm at 300 dpi |
| USPS IMpbPublication 199; Parcel Labeling Guide | Up to 34 digits; X 13 to 21 mil (15 to 17 preferred); at least 3/4 in tall; clear zone 10 X each side, 1/4 in recommended; 1/8 in above |
| IMpb on a 4 in labelOur calculation, GS1 (11N + 66) X | 264 narrowest bars with quiet zones: 3.43 in at 13 mil, 3.96 in at 15 mil, 4.49 in at 17 mil; at 203 dpi only 3 dots (14.76 mil) fits |
| UPS 1Z barcodeGuide to Labeling 2017 | X 15 to 21 mil; at least 0.7 in tall; 2.84 to 4.47 in wide with quiet zones |
| USPS layout | Payment segment about 1 5/16 in high; IMpb segment about 1 1/2 in |
| Label stockZebra Z-Perform 1000D | Direct thermal, phenol-free paper; 5.3 mil thick in all on a 40 lb kraft liner |
| Where it goesFedEx | Top or largest side, at least 2cm from edges if possible; not wrapped round edges |
Sources: Zebra · Zebra · Zebra · Brother · Office Depot · USPS · USPS · GS1 · UPS · Zebra · FedEx
101.6 × 152.4 mm: 4 in wide, 6 in tall. A6 is 105 × 148 mm, and 100 × 150 mm is a third size, sold on a 103 mm liner instead of 104 mm.
Yes. UPS’s guide uses 4 × 6 or 4 × 8 in when the extended area is used and 4 × 4.25 in otherwise; FedEx prints 4 × 6 as Format 435 and 4 × 6.75 in with a doc-tab.
475 on a 1 in core (Uline S-22378, Labelident), 1,000 on a 3 in core (Uline S-6264) and 2,450 on a 12 in roll; FedEx Office rolls work out to 425 and 925.
A 4-inch thermal printer whose print width covers 101.6 mm: the Zebra ZD421 and ZT411 print 104 mm at 203 dpi. A 2-inch model such as the ZD411 (56 mm) cannot.
A 34-digit USPS IMpb is 264 narrowest bars wide with quiet zones: 3.96 in at 15 mil, but 4.49 in at 17 mil, wider than the label. At 203 dpi that leaves a 3-dot bar, 14.76 mil.
Buyers ask for the label size in inches and millimetres, the liner width and the gap, the core and the roll diameter, labels a roll and rolls a case, the face stock and whether it is phenol-free, the adhesive and its temperature range, and which printers and carriers it suits. Mark the real roll, its liner and its core on your own photo in SizeMarker, as in the picture at the top, and send one product card for WhatsApp or WeChat.
Shipping the parcel
Volumetric weight calculatorDimensional weight of the labelled carton
