THE NUMBERS, EXPLAINED
How to use this calculator.
Centered rectangular window; overlap hides the same amount of artwork on every edge. Mat outer size equals the entered frame opening.
Start with your inputs
Enter artwork width (mm), artwork height (mm), artwork overlap under mat on each edge (mm), frame opening width (mm), frame opening height (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Artwork width (mm) | 200 |
| Artwork height (mm) | 150 |
| Artwork overlap under mat on each edge (mm) | 5 |
| Frame opening width (mm) | 300 |
| Frame opening height (mm) | 250 |
A worked example
With the example inputs above, mat window width (mm) is 190. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Mat window width (mm) | 190 |
| Mat window height (mm) | 140 |
| Left and right border (mm) | 55 |
| Top and bottom border (mm) | 55 |
How this is calculated
Mat window width (mm)
Subtract overlap on both horizontal edges.
Mat window height (mm)
Subtract overlap on top and bottom.
Left and right border (mm)
Split remaining mat width equally.
Top and bottom border (mm)
Split remaining mat height equally.
Symbols and units
- a
- Artwork width (mm)
- b
- Artwork height (mm)
- c
- Artwork overlap under mat on each edge (mm)
- d
- Frame opening width (mm)
- e
- Frame opening height (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Centered rectangular window; overlap hides the same amount of artwork on every edge. Mat outer size equals the entered frame opening.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Mat window width (mm); Mat window height (mm); Left and right border (mm); Top and bottom border (mm). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Centered rectangular window; overlap hides the same amount of artwork on every edge. Mat outer size equals the entered frame opening.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax Prealgebra 2e — arithmetic and proportions ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →