Centered double-mat dimensions
Mistake: Entering the frame outside dimensions or treating overlap as a total.
Fix: Measure the internal rebate and enter overlap separately for each edge; the formula doubles it.
Calculators · Free
Centered double-mat dimensions
Plan two centered mat openings from artwork, frame, overlap and reveal measurements.
01Enter your values
Runs in your browserRuns offline in your browser. Once the page and required files have loaded, processing needs no internet.
02Centered double-mat dimensions
Runs in your browser
How it works
Plan two centered mat openings from artwork, frame, overlap and reveal measurements.
Wₗ = Wₐ − 2o; Wᵤ = Wₗ + 2r; b = (Wf − Wᵤ)/2
Rectangular, centered openings only. Overlap is per edge and reveal is the visible width of the lower mat. Both openings must be positive and fit inside the frame. Measurements describe cut geometry, not bevel allowance, conservation mounting, frame fit tolerance or artwork safety. Calculation works offline after loading.
Your data stays yours
Inputs are processed on this page and are never sent to a server.
About this tool
Use tool ↑Plan two centered mat openings from artwork, frame, overlap and reveal measurements.
Subtract twice the overlap from each artwork dimension to get the lower mat opening. Add twice the reveal to each opening dimension to get the upper mat opening. Center both in the specified frame rebate size. Each border is half the difference between the frame dimension and the corresponding opening dimension.
How to use it
- Enter your values
Artwork width · Artwork height · Frame rebate width · Frame rebate height · Overlap per edge · Lower-mat reveal
- Calculate / generate
Plan two centered mat openings from artwork, frame, overlap and reveal measurements.
- Result
Lower opening width: 190 mm Lower opening height: 290 mm Upper opening width: 196 mm
Calculation method
- Subtract twice the overlap from each artwork dimension to get the lower mat opening.
- Add twice the reveal to each opening dimension to get the upper mat opening.
- Center both in the specified frame rebate size.
- Each border is half the difference between the frame dimension and the corresponding opening dimension.
Wₗ = Wₐ − 2o; Wᵤ = Wₗ + 2r; b = (Wf − Wᵤ)/2
Centered double-mat dimensions
- Artwork width
- 200 mm
- Artwork height
- 300 mm
- Frame rebate width
- 300 mm
- Frame rebate height
- 400 mm
- Overlap per edge
- 5 mm
- Lower-mat reveal
- 3 mm
Result
Lower opening width: 190 mm Lower opening height: 290 mm Upper opening width: 196 mm
Frequently asked questions
What does this result assume?
Rectangular, centered openings only. Overlap is per edge and reveal is the visible width of the lower mat. Both openings must be positive and fit inside the frame. Measurements describe cut geometry, not bevel allowance, conservation mounting, frame fit tolerance or artwork safety. Calculation works offline after loading.
Where does my data go?
Calculations run on your device. Form inputs are not sent to a server.
Terms and definitions
Enter your values
- Measurement system
The initial choice follows your browser region. Your choice is remembered on this device. Gallons are US gallons. Switching units keeps your numbers unchanged and interprets them in the new unit.
Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
- Artwork width
Measured width of the artwork sheet being overlapped.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.000001 · Maximum: 1000000000000 mm
- Artwork height
Measured height of the artwork sheet being overlapped.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.000001 · Maximum: 1000000000000 mm
- Frame rebate width
Internal backing-board width available inside the frame, not its outside dimension.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.000001 · Maximum: 1000000000000 mm
- Frame rebate height
Internal backing-board height available inside the frame.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.000001 · Maximum: 1000000000000 mm
- Overlap per edge
Width covered by the lower mat on each edge of the artwork.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0 · Maximum: 1000000000000 mm
- Lower-mat reveal
Visible lower-mat width between the two openings; zero gives coincident openings.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0 · Maximum: 1000000000000 mm
Result
- Result
Subtract twice the overlap from each artwork dimension to get the lower mat opening. Add twice the reveal to each opening dimension to get the upper mat opening. Center both in the specified frame rebate size. Each border is half the difference between the frame dimension and the corresponding opening dimension.
Calculated from your entries using the method below.
- Lower opening width
Artwork width minus two overlaps.
Calculated from your entries using the method below.
- Lower opening height
Artwork height minus two overlaps.
Calculated from your entries using the method below.
- Upper opening width
Lower opening width plus two reveals.
Calculated from your entries using the method below.
- Value
Subtract twice the overlap from each artwork dimension to get the lower mat opening. Add twice the reveal to each opening dimension to get the upper mat opening. Center both in the specified frame rebate size. Each border is half the difference between the frame dimension and the corresponding opening dimension.
Calculated from your entries using the method below.
- Unit
Subtract twice the overlap from each artwork dimension to get the lower mat opening. Add twice the reveal to each opening dimension to get the upper mat opening. Center both in the specified frame rebate size. Each border is half the difference between the frame dimension and the corresponding opening dimension.
Calculated from your entries using the method below.
- Upper opening height
Lower opening height plus two reveals.
Calculated from your entries using the method below.
- Upper side borders
Equal left and right borders from the frame rebate to the upper opening.
Calculated from your entries using the method below.
- Upper top and bottom borders
Equal top and bottom borders from the frame rebate to the upper opening.
Calculated from your entries using the method below.
Common mistakes and quick fixes
Limits and key assumptions
- Rectangular, centered openings only. Overlap is per edge and reveal is the visible width of the lower mat. Both openings must be positive and fit inside the frame. Measurements describe cut geometry, not bevel allowance, conservation mounting, frame fit tolerance or artwork safety. Calculation works offline after loading.
- Displayed results may be rounded; rounding does not add measurement precision.