Picture Frame Size & Cost Calculator
Use this free online frame calculator to estimate inner opening size, outside frame dimensions, cut lengths, total moulding required, and a simple cost estimate.
How this online frame calculator helps
Framing projects often go wrong for one reason: tiny measurement mistakes. A difference of just 1/8 inch can create a loose fit, visible gaps, or a frame that simply won’t assemble cleanly. This online frame calculator is designed to prevent those common problems by turning your artwork dimensions into a practical cut and material plan.
Whether you are framing a poster, photo print, canvas panel, diploma, or custom art piece, the tool helps you estimate:
- Inside opening dimensions
- Outside frame dimensions
- Miter cut lengths for each side
- Total moulding needed with waste allowance
- A basic materials cost estimate
What each input means
Artwork width and height
This is the actual size of what you are framing. Measure the piece directly, not the old frame. If paper edges are irregular, use the visible area you want to show.
Mat border per side
If using a mat, enter the border width on one side. The calculator adds this on both sides of width and height. Enter 0 for a no-mat frame.
Fitting allowance per dimension
This gives your content room inside the frame opening so assembly is easier and seasonal movement is less likely to cause binding. A common allowance is 1/16 to 1/8 inch total per dimension.
Moulding face width
This is the visible width of the frame from inner edge to outer edge on the front face. It determines outside size and long-point miter cuts.
Waste allowance
Extra moulding is recommended for saw kerf, defects, grain matching, and mistakes. Many framers use 10% to 15% for routine work and more for expensive hardwood profiles.
Core formulas used in the calculator
The calculator uses straightforward geometry suitable for typical 45° mitered rectangular frames:
- Opening width = artwork width + (2 × mat border) + fitting allowance
- Opening height = artwork height + (2 × mat border) + fitting allowance
- Outside width = opening width + (2 × face width)
- Outside height = opening height + (2 × face width)
- Moulding perimeter = 2 × (outside width + outside height)
- Moulding with waste = perimeter × (1 + waste%)
- Fill area = opening width × opening height
Best practices for accurate frame builds
1) Measure twice in consistent units
Switching between inches and centimeters mid-project can introduce avoidable errors. Pick one unit and stick to it across measuring, cutting, and ordering materials.
2) Verify your saw setup before final cuts
A perfectly calculated length can still fail if your miter angle is slightly off. Test cuts on scrap stock first, then confirm corner closure before cutting expensive moulding.
3) Plan for glazing type and thickness
Acrylic, glass, foam board, and mat stacks affect fit depth. If your rabbet is shallow, you may need thinner materials or spacers.
4) Don’t skip waste factors
Many first-time builders under-order moulding. Even careful cuts produce kerf loss and occasional rejects. The waste allowance in this calculator reduces the chance of running short.
Example workflow
Suppose your artwork is 16 × 20 inches, mat border is 2 inches, face width is 1.25 inches, and fitting allowance is 1/8 inch. After calculation, you get:
- A larger opening to accommodate art + mat + fit clearance
- Outside dimensions that reflect moulding width on all sides
- Long-point cut lengths for top/bottom and left/right pieces
- Total linear moulding including your waste percentage
From there, you can make a clean cut list, buy materials once, and reduce trial-and-error in the workshop.
Frequently asked questions
Does this work for metric framing?
Yes. Select centimeters and keep all measurements and cost units in centimeters and square centimeters.
Are these measurements exact for every profile?
They are accurate for common rectangular, 45° mitered profiles. Specialty profiles, slip frames, float mounts, or non-rectangular builds may require additional adjustments.
Can I use this as a picture frame cost calculator?
Absolutely. Enter your local unit pricing for moulding, glazing, mat board, backing, and hardware to produce a quick estimate. For client quotes, add labor, overhead, and markup separately.
Final tip
A good frame project starts with clear dimensions and consistent assumptions. Use this online frame calculator before you cut anything, save your settings, and keep a small build log for repeatable results on future projects.