Shipping Box and Poly Mailer Fit Calculator for 3D Prints
Add the items and quantities going into one shipment, then compare your box sizes. PlyOps checks rotations and group layouts to find the smallest likely box among your options. Mailers and tight fits remain a physical judgment call.
Find a box for your items
Free to use in this browser. Nothing is saved unless you choose to continue in PlyOps.
Items to pack
Build your shipment
Add each item type and its quantity. Measure after wrapping, before the outer package.
1 item · up to 100
in
in
Shipping containers
Enter internal usable dimensions, not the outside of the package. Inserts, padding, and bubble bags do not belong in this list.
Group fit check
Package fit results
Smallest likely box by internal volume, among your entered sizes and the layouts tested. Mailers and tight fits need review.
6 × 4 × 2 box
Smallest likely boxFits as single item with 0.65 in x 0.55 in x 0.3 in remaining after 0.13 in padding around the group.
Single item · 1 item
Smallest likely box
6 × 4 × 2 in
8 × 6 × 3 box
Fits as single item with 2.65 in x 2.55 in x 1.3 in remaining after 0.13 in padding around the group.
Single item · 1 item
Likely fit
8 × 6 × 3 in
10 × 8 × 4 box
Fits as single item with 4.65 in x 4.55 in x 2.3 in remaining after 0.13 in padding around the group.
Single item · 1 item
Likely fit
10 × 8 × 4 in
10 × 7 mailer
The item plus padding does not fit any checked rotation.
No fit
10 × 7 × 0.75 in
Check saved packaging for a product
Carry this item’s dimensions (5.1 × 3.2 × 1.45 in) into a product review. Compare your saved boxes and mailers; temporary package rows here are not imported.
This result is available in this tab for up to two hours. Nothing is saved until you review and confirm it. How result handoff works.
See the fit method, rotations, and limitsOpen the detailed reference when you want to check how the result is calculated or where the tool stops.
Use inside dimensions, then test the real pack
Add different items and a quantity for each. This calculator uses the same dimensional layout checks as PlyOps’s Box Fit Optimizer: rows, columns, grids, rotations, and optional stacks. It recommends the smallest entered rigid box by internal volume with a tested likely fit. It does not search every possible arrangement or prove that the items are protected well enough to ship.
Repeat the check for the boxes and mailers you actually keep on hand. Start with the smallest likely fit, pack one sample with the intended protection, and move up a size when the closure or protection is not right.
Method last checked .
A practical fit check
1. List the items
Add each different item and its whole-number quantity. Measure after any wrap, sleeve, or bundled parts, but before the outer box. All item rows must be complete.
2. Measure usable space
Enter the package's internal dimensions. Outside dimensions include walls and do not tell you how much room the product has.
3. Add clearance and spacing
Outer clearance adds twice that amount to every group dimension. Space between items leaves a separate gap between neighboring items. Turn stacking off when items must stay in one layer.
4. Compare tested layouts
PlyOps tries rigid rotations and several group layouts against each package's internal dimensions. The result names the arrangement that was checked.
5. Read the result literally
Smallest likely box means the least internal volume among the entered boxes with a tested likely fit. Needs review covers mailers and tight clearances. No fit means none of the tested layouts fit; a different arrangement may still work.
6. Pack one sample
Close the package with the intended protection, then check movement, pressure points, seams, and closure before standardizing it.
The six rigid rotations
A rigid item can turn so any one of its dimensions lines up with any package dimension. The layout engine considers these six axis assignments when checking items and their arranged group:
- 1.length × width × height
- 2.length × height × width
- 3.width × length × height
- 4.width × height × length
- 5.height × length × width
- 6.height × width × length
Equal sides can make two or more rotations identical. Removing those duplicates does not remove a possible fit.
Worked box example
A packed part measures 5.10 × 3.20 × 1.45 inches. With 0.125 inch of clearance on every side, the checked envelope becomes 5.35 × 3.45 × 1.70 inches. That orientation fits inside a box with 6.00 × 4.00 × 2.00 inches of usable interior space.
If 6 × 4 × 2 describes the outside of the box, this result is not valid. Measure the inside space and run the comparison again.
Flexible packages need a physical check
A poly or padded mailer can bend around a product, so three flat measurements do not describe every usable shape. Seams, gussets, closure space, material stiffness, sharp corners, and the way the product is wrapped can all change the real fit. PlyOps therefore leaves flexible-package results at Needs review.
Candidate rows should contain only an actual outer shipping package that can be handed to the carrier: a shipping box or a carrier-ready flexible mailer. Bubble bags used inside a shipment, padding, inserts, labels, and void fill are supporting supplies, not fit candidates.
Related 3D print business tools
3D print pricing
Calculate filament, machine, labor, packaging, and marketplace costs, then see profit, margin, break-even price, and a target sale price.
Calculate a priceFilament and stock reorders
Set a practical low-stock point and restock quantity for filament, finished products, hardware, or shipping supplies.
Set reorder levelsInventory count sheet
Prepare a full or cycle count with locations, blind or expected quantities, notes, and optional item barcodes.
Build a count sheet