How to size an acrylic file box, file holder or paper tray for A4, US Letter and Legal: the paper sizes, the clearance documents need, how deep a box must be for a given number of sheets, and the measurements to put on the drawing.
Inside dimensions are confirmed at drawing review before a sample is made
Size an acrylic file box from the inside out. Start with the paper: A4 is 210 × 297 mm, US Letter is 215.9 × 279.4 mm (8.5 × 11 in) and US Legal is 215.9 × 355.6 mm (8.5 × 14 in). Add clearance so documents slide in and out — a few millimetres for loose paper, more for folders and sleeves, and the measured size of the binder for binders. For depth, allow about 0.1 mm per sheet of standard 80 g/m² or 20 lb paper, so 500 sheets need about 50 mm plus clearance. A box that must take both A4 and Letter needs a width of at least 215.9 mm and a depth of at least 297 mm inside. Put inside dimensions, not outside, on the drawing, and state the wall thickness separately.
Paper sizes by market
| Size | Millimetres | Inches | Main markets |
| A4 | 210 × 297 | 8.27 × 11.69 | Europe, Asia, Middle East, Africa, Australia, Latin America (most) |
| US Letter | 215.9 × 279.4 | 8.5 × 11 | United States, Canada, Mexico, Philippines |
| US Legal | 215.9 × 355.6 | 8.5 × 14 | United States legal and government use |
| A5 | 148 × 210 | 5.83 × 8.27 | Notebooks, menus, brochures |
| A3 | 297 × 420 | 11.69 × 16.54 | Drawings, plans, large prints |
A4 is narrower and longer than Letter: 5.9 mm narrower and 17.6 mm longer. A box sized tightly for one will not take the other.
Clearance: what goes in decides the inside size
| Contents | Starting allowance on width and length | Why |
| Loose paper | A few millimetres | Sheets must drop in and lift out without catching on the walls |
| Paper in a folder or clear sleeve | More than loose paper; measure the folder | Folders are larger than the paper they hold and have covers that flex |
| Ring binders and lever-arch files | The measured binder plus clearance | Binder sizes vary between brands and markets; measure the ones your customers use |
| Magazines and catalogues | The largest title the product is sold for | Magazine formats vary more than office paper |
These are starting points, not standards. Confirm with the actual documents or folders your customers use, and approve a sample before production.
How deep for a given number of sheets
| Sheets of 80 g/m² (20 lb) paper | Stack height, approx. |
| 100 | 10 mm |
| 250 | 25 mm |
| 500 (one ream) | 50 mm |
| 1,000 | 100 mm |
Based on about 0.1 mm per sheet for standard office paper; heavier paper is thicker. Add clearance above the stack so the top sheet can be picked up, and more if the box has a lid.
What to put on the drawing
| Item | Example |
| Inside width, length and height | Inside 222 × 303 × 60 mm, to take A4 and Letter loose paper |
| Wall thickness | Stated separately from the inside size |
| Orientation | Paper flat (tray) or upright (file holder, magazine file) |
| Cut-outs | Finger notch, front cut-away, label window |
| Stacking | Whether units stack, and how they locate on each other |
| Construction | Bent from one sheet, bonded panels, or both |
| Market | A4, Letter or both, so the size is checked against the right paper |
Bent and bonded construction change how corners and inside dimensions are measured; see bent vs bonded acrylic boxes.
File boxes at AcrylicFabWorks
AcrylicFabWorks, the acrylic division of SinoPlastix, makes acrylic file boxes, file holders, magazine files, paper trays and desk organizers to brands’ designs in Suzhou, China, from Calypto cast acrylic sheet cast on the same site. We check inside dimensions against the paper and folders at drawing review, before the sample is made. Production starts at 20 pieces per design; samples take 48 hours and production 7 days from drawing approval. See acrylic file boxes and desk organizers.
FAQ
What size is an A4 acrylic file box?
The inside must be larger than A4 paper, which is 210 × 297 mm. Add a few millimetres for loose paper and more for folders or sleeves; the outside size then adds the wall thickness.
Will an A4 file box hold US Letter paper?
Only if it is at least 215.9 mm wide inside. Letter is 5.9 mm wider than A4 but 17.6 mm shorter, so a box for both needs at least 215.9 mm width and 297 mm length inside.
How deep should a paper tray be for 500 sheets?
About 50 mm of stack height for standard 80 g/m² or 20 lb paper, plus clearance above the stack so the top sheet can be lifted out.
Should I give inside or outside dimensions?
Give inside dimensions for anything that holds paper or folders, and state the wall thickness separately. The supplier then works out the outside size and the cut parts.
Sizing an acrylic file range?
Send the paper size, contents and quantity per design. We reply within 12 hours.
Or email [email protected]