Check Whether a Mat Opening Leaves Your Chosen Artwork Border — Free
A mat opening only leaves a border when it is wider than the artwork. Divide the width difference between the two sides and check it against the margin you planned.
The proof surface
Curtain fullness compares fabric width with a track. This gauge checks the left-and-right border of a single artwork inside a mat opening; it does not plan curtain gathers or frame clearance.
Why the flat version breaks
Comparing the frame outside dimension
The frame does not define the visible mat opening.
Forgetting hidden overlap
A mat can cover some artwork; measure the image that should remain visible.
Expecting the same margin vertically
Portrait and landscape dimensions can differ; check both axes.
How to work the mat-window border gauge
Measure the portion that should remain visible after any overlap under the mat. The outer paper edge can be wider than the printed image.
The mat window is the relevant dimension. Enter both widths in millimetres.
Side border = (opening width − artwork width) ÷ 2. A 220 mm opening around 200 mm of art leaves 10 mm per side.
Use a second row for the vertical dimension. Mat overlap, bevels, paper curl and frame fit are not included.
What the mat-window border gauge replaces
| Question | Before | Visible working |
|---|---|---|
| Comparing the frame outside dimension | The frame does not define the visible mat opening. | Measure the opening, not the frame |
| Forgetting hidden overlap | A mat can cover some artwork; measure the image that should remain visible. | Compute each side margin |
| Expecting the same margin vertically | Portrait and landscape dimensions can differ; check both axes. | Check height independently and test physically |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Framing geometry only, not conservation, glazing, mounting or archival advice. Confirm the actual opening and overlap with the framer, and use conservation guidance for valuable or fragile work. The estimate cannot inspect a physical mat or the condition of the artwork.
Data note: Everything runs in this browser tab on the mat-window border gauge: your artwork | art width mm | mat opening width mm stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a meter band gauge
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the mat-window border gauge reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The mat-window border gauge reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the check whether a mat opening leaves your chosen artwork border companionBoundary
Framing geometry only, not conservation, glazing, mounting or archival advice. Confirm the actual opening and overlap with the framer, and use conservation guidance for valuable or fragile work. The estimate cannot inspect a physical mat or the condition of the artwork.
What this is built on
- Method: the equation is stated next to the result and uses only quantities entered by the reader.
- All sample records are invented examples. No standard, tariff, product rate, schedule or policy is fetched or represented as verified.
- For any threshold or rule, use the current value from the provider, handbook or qualified professional responsible for it.
Before: The frame does not define the visible mat opening. After: the mat-window border gauge shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this mat-window border gauge, an external AI text tool may help format non-sensitive notes if you already use one. No AI service or account is required: manual entry completes the same free core calculation. Do not paste private or sensitive data. Review every value against the source before using it.
Format my non-sensitive notes for a mat-window border gauge. Return plain rows only: artwork | art width mm | mat opening width mm. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: artwork | art width mm | mat opening width mm. No AI response is executed as code.
Walk three labelled examples
First reading. The invented sample Landscape print | 200 | 220 uses desired border per side in millimetres = 12. The displayed narrowest side border is 10.00000 border mm per side. Follow the row note back to the measurements and conversion rather than treating the headline number as a recommendation. The sample is deliberately concrete so the reader can reproduce the arithmetic by hand.
Changed assumption. The alternate input Small drawing | 200 | 228 produces 14.00000 border mm per side for the displayed summary. Compare it with the first reading to see which entered quantity moves the result. In a real plan, change only the assumption that has a traceable source; do not tune a value just to make a row pass.
Boundary case. With Exact border | 210 | 234 and the same setting, the worked result is 12.00000 border mm per side. This case shows how the arithmetic behaves at a useful edge, not that the underlying process has been measured or verified. Check the boundary statement beside the result and confirm any consequential input with the responsible person before acting.