A pizza box needs an internal size about 0.5 to 1 inch (1 to 2 cm) larger than the pizza. For a 12 inch pizza that means roughly 12.5 to 13 inches inside, or 32 to 33 cm. Enter your pizza diameter below to get the internal size for your dough type, the nearest common box size and an estimate of the external size for E, B or EB flute board.
The rules match the ones in our guide to pizza box sizes, which also covers box depth, party formats and tolerances.
What size box for a 12 inch pizza?
Use a box with an internal size of about 12.5 to 13 inches (32 to 33 cm). Depending on the supplier, the same box is sold as a "12 inch box" or a "13 inch box", so compare internal dimensions in millimetres rather than the name. The calculator gives 12.75 in (323.9 mm) for a 12 inch pizza at standard clearance, and the nearest common box is the 13 inch internal size.
How does the calculator work?
It follows three steps.
- Internal size = pizza diameter + clearance. Clearance is 0.5, 0.75 or 1 inch when you enter inches, and 1, 1.5 or 2 cm when you enter centimetres. Pick the lowest for a pressed or machine-formed base, the highest for hand-stretched dough with a puffy crust, and the middle value if unsure.
- Nearest common box = the smallest common internal size that is at least as large as the internal size you need. If the next size up is much larger, the result says so, and a custom size may suit better.
- External size = internal size + 2 × board caliper + about 2 mm for wall folds, in each direction. This is an estimate: the exact figure depends on the die design and how the walls are folded.
Measure 20 to 30 real pizzas from a normal service before fixing a size. The pizza is usually the largest source of variation, not the box.
Pizza box size table (inches, cm and mm)
| Pizza diameter | Internal size: low / standard / high clearance | Same in mm | Nearest common box (internal) |
|---|---|---|---|
| 10 inch (25.4 cm) | 10.50 / 10.75 / 11.00 in | 267 / 273 / 279 mm | 11 in |
| 12 inch (30.5 cm) | 12.50 / 12.75 / 13.00 in | 318 / 324 / 330 mm | 13 in |
| 14 inch (35.6 cm) | 14.50 / 14.75 / 15.00 in | 368 / 375 / 381 mm | 15 in |
| 16 inch (40.6 cm) | 16.50 / 16.75 / 17.00 in | 419 / 425 / 432 mm | 17 in |
| 18 inch (45.7 cm) | 18.50 / 18.75 / 19.00 in | 470 / 476 / 483 mm | 19 in |
| 26 cm (10.2 in) | 27.0 / 27.5 / 28.0 cm | 270 / 275 / 280 mm | 28 cm |
| 30 cm (11.8 in) | 31.0 / 31.5 / 32.0 cm | 310 / 315 / 320 mm | 32 cm |
| 33 cm (13.0 in) | 34.0 / 34.5 / 35.0 cm | 340 / 345 / 350 mm | 35 cm |
| 36 cm (14.2 in) | 37.0 / 37.5 / 38.0 cm | 370 / 375 / 380 mm | 38 cm |
| 40 cm (15.7 in) | 41.0 / 41.5 / 42.0 cm | 410 / 415 / 420 mm | 42 cm |
Internal sizes are shown for low, standard and high clearance. Treat the table as a starting point for samples, not a specification.
Which common box sizes does the tool use?
The tool matches against the upper end of the typical internal range for each nominal size, so a box chosen this way is never tighter than your clearance setting.
| Box made for | Common nominal internal size used by the tool |
|---|---|
| 10 inch pizza | 11 in (279 mm) |
| 12 inch pizza | 13 in (330 mm) |
| 14 inch pizza | 15 in (381 mm) |
| 16 inch pizza | 17 in (432 mm) |
| 18 inch pizza | 19 in (483 mm) |
| 26 cm pizza | 28 cm (280 mm) |
| 30 cm pizza | 32 cm (320 mm) |
| 33 cm pizza | 35 cm (350 mm) |
| 36 cm pizza | 38 cm (380 mm) |
| 40 cm pizza | 42 cm (420 mm) |
Inch results use the inch list and centimetre results use the centimetre list. Party, pinsa, slice and deep-pan formats are sized from the tray or product, so they are not part of this round-pizza tool; see pizza box sizes for those.
Internal versus external size
The internal size decides whether the pizza fits. The external size decides whether the box fits your delivery bags, hot-holding shelves and storage. The difference is about two board thicknesses plus a small allowance for the folded walls.
| Flute | Board caliper (typical) | External larger than internal (each direction, approx.) | External size for a 345 mm internal box (33 cm pizza, standard clearance) |
|---|---|---|---|
| E | 1.1-1.8 mm | 4.2 to 5.6 mm | 349.2 to 350.6 mm |
| B | 2.5-3.2 mm | 7.0 to 8.4 mm | 352.0 to 353.4 mm |
| EB | 4.0-5.0 mm | 10.0 to 12.0 mm | 355.0 to 357.0 mm |
Worked example: a 33 cm pizza at standard clearance needs 345 mm inside. On B-flute the box measures about 352.0 to 353.4 mm outside in each direction. If you change from E-flute to B-flute for strength, keep the internal size and check the larger outside size against your bags and shelves.
What to send with a quotation
- Nominal pizza sizes and the measured diameter range of real pizzas.
- Required internal length, width and depth in millimetres.
- Maximum external size, if bags or shelves limit it.
- Board preference, if known.
The packaging RFQ guide lists the remaining fields. Final dimensions and tolerances are confirmed at quotation and technical review.