Enter the size of your diploma, certificate or transcript and this calculator tells you the frame opening you need and the mat width that fits it. It also identifies whether the document is US Letter, A4, A3 or one of the non-standard formats that turn up often.
How to use it
- Measure the document flat, in inches or millimetres. Width first, then height.
- Enter both numbers and pick your unit.
- Read the matched format and the frame size for a 1.5, 2 or 3 inch mat.
If the document has been rolled, press it flat between two clean boards for a day before measuring. A curled edge can add a quarter inch to your numbers.
What the numbers mean
- Frame opening — the hole the artwork shows through. This is the number that has to match the document plus the mat, not the document alone.
- Mat width — the border between the document edge and the frame. Two to three inches is the usual range for a diploma; narrower looks cramped, wider starts to dwarf the document.
- Frame size listed in shops — almost always the outside size, and the opening is smaller. Always measure the opening before buying.
Why the opening is not the same as the document size
A mat is cut slightly smaller than the document — about 1/8 inch on each side — so the mat overlaps the edge and holds the document in place. That overlap is what keeps the document from slipping, and it is why a mat cut to exactly the document size is a mistake.
Standard sizes this tool recognises
| Format | Inches | Millimetres |
|---|---|---|
| US Letter | 8.5 × 11 | 216 × 279 |
| A4 | 8.27 × 11.69 | 210 × 297 |
| A3 | 11.69 × 16.54 | 297 × 420 |
| A5 | 5.83 × 8.27 | 148 × 210 |
| 8 × 10 in | 8 × 10 | 203 × 254 |
| 9 × 12 in | 9 × 12 | 229 × 305 |
| 11 × 14 in | 11 × 14 | 279 × 356 |
| Legal | 8.5 × 14 | 216 × 356 |
If your document is not a standard size
You have two options, and the cheaper one is almost always the mat. A custom mat cut to your document size fits inside a standard frame, so you keep the frame you already like. A custom frame costs several times as much and gives you the same result.
Background on how the two standards differ: A4 vs Letter certificate sizes, and the full list of formats: what size is a diploma.
Common questions
Does the calculator work in millimetres?
Yes — switch the unit selector to millimetres and enter the document size as printed on the certificate or measured with a ruler.
What mat width should I choose?
Two inches is the safe default for a diploma. Use 1.5 inches if the frame is small or the document is large, and 3 inches for a single document on a large wall.
My document is 8.27 × 11.69 — is that A4?
Yes. That is A4 exactly, and the calculator will say so.
Why does the tool say non-standard when my document looks normal?
Because it is measuring against the standard formats rather than assuming. Older diplomas are frequently 8 × 10 or 9 × 12, and a document printed slightly off-trim will fall outside the tolerance.
Related guides
- Diploma frame sizes and mat widths
- What size is a diploma?
- How to print a diploma at home
- Diploma covers vs frames
Everything sold on this site is a novelty reproduction for display, keepsake and prop use. It is not an official record and cannot be used to verify a qualification.