Picture Frame Calculator
Size a picture, mat, glazing area, frame opening, outer frame, and total molding length from one consistent set of measurements.
Frame inputs
The calculator opens with a complete demonstration setup. Replace any value and results update automatically.
Changing units converts the current numeric measurements.
Frame adjustments
Live results
All dimensions use the selected unit. Molding length assumes a four-sided rectangular frame with 45° corner joints and no waste allowance.
Molding length
64.00 in
Glaze height
16.00 in
Glaze width
12.00 in
Inner frame height
15.85 in
Inner frame width
11.85 in
Outer frame height
18.00 in
Outer frame width
14.00 in
Dimension breakdown
A compact cross-check of the picture, picture-plus-mat glaze size, inner opening, and outer frame.
| Layer | Height | Width | Unit |
|---|---|---|---|
| Picture | 12.00 | 8.00 | in |
| Glaze size | 16.00 | 12.00 | in |
| Inner frame | 15.85 | 11.85 | in |
| Outer frame | 18.00 | 14.00 | in |
How to use this picture frame calculator
What this calculator does
This calculator turns a picture size, optional mat margins, frame molding width, rabbet overlap, and a small fitting allowance into the main dimensions needed to plan a rectangular picture frame. It reports the picture-plus-mat glaze size, the inner frame opening, the outer frame size, and the total molding length around the outside perimeter. It is a measurement-planning tool rather than a cutting optimization system: it does not add saw-kerf waste, defect allowance, stock-length optimization, backing-board thickness, or a safety margin for a particular joinery method. For valuable photographs or works on paper, dimensions are only one part of good framing practice; the Library of Congress provides detailed preservation guidelines for matting and framing, including guidance on matboard, glazing, backing, and keeping the object away from the glazing surface.
When to use it
Use it when you are ordering a custom frame for a known print size, comparing how different mat widths change the finished footprint, checking whether a frame will fit a wall or shelf location, or estimating how much molding a four-sided frame needs before you add workshop waste. It is also useful for sanity-checking a framer's quoted inner and outer dimensions when you know the picture, mat, and molding widths.
How to calculate
- The calculator opens with a ready-to-use demonstration: a 12 × 8 in picture, 2 in mat on each axis, 1 in molding, 0.125 in rabbet, and 0.05 in fitting allowance. The matching Excel workbook is validated and available immediately.
- Choose the Unit of measurement. Switching among inches, centimeters, and millimeters converts the numbers already in the controls, so the physical size does not change.
- Replace Border width, Picture height, and Picture width. These are the required measurements. Results update live without a Calculate button.
- Enter Mat height and Mat width if you want a mat. Leave either optional field blank to treat that mat dimension as zero. Open Frame adjustments to set Rabbet width and Fudge factor; blank optional adjustment fields are treated as zero.
- Read the live result cards and the Dimension breakdown table, then use Download Excel to save the current typed measurements and calculated outputs. Reset clears the demonstration and all entered measurement fields, closes Frame adjustments, removes calculated content, and may disable Download Excel until the required fields form a valid state again.
Input guide
Unit of measurement is a required selector with in, cm, or mm; it changes only presentation and converts existing values. Border width is the positive width of the visible frame molding, such as 1 in; a larger border increases both outer dimensions and total molding length. Picture height and Picture width are required positive decimal measurements, such as 12 in and 8 in; swapping them rotates the same rectangular size, while increasing either one increases the corresponding glaze, inner, and outer dimension. Numeric fields accept ordinary decimal notation with a dot as the decimal separator and correctly placed comma thousands separators; scientific notation, unit symbols pasted into the field, decimal commas, negative values, and malformed grouping are rejected rather than silently reinterpreted.
Mat height is the top-and-bottom mat amount used in the height calculation, and Mat width is the left-and-right amount used in the width calculation. Both are optional nonnegative decimals; 2 in is a typical example for a modest presentation border. Higher mat values increase glaze and outer dimensions. Rabbet width is an optional nonnegative overlap of the molding over the framed package; 0.125 in is the demonstration value. Increasing it reduces the calculated visible inner opening. Fudge factor is an optional nonnegative per-side fitting allowance; 0.05 in is the demonstration value. Increasing it slightly enlarges the inner opening calculation. A common mistake is to use rabbet depth – the front-to-back recess depth – where this calculator expects rabbet width, the face overlap that changes the opening dimension.
Output guide
Glaze height and Glaze width measure the picture plus twice the corresponding mat amount; they are exact geometric identities in the selected unit. Inner frame height and Inner frame width estimate the visible frame opening after subtracting rabbet overlap and adding the selected fitting allowance on both sides. Outer frame height and Outer frame width give the overall nominal footprint using picture + two mat margins + two border widths. Molding length is the perimeter of that outer rectangle, so it is an estimate of net frame molding rather than a purchasing recommendation; real projects normally need extra stock for kerf, miters, defects, and grain matching.
The Dimension breakdown table repeats the same current model in four rows: Picture, Glaze size, Inner frame, and Outer frame. Its Height and Width columns are numeric measurements, while Unit shows the active unit. Zero mat values make the picture and glaze rows equal. Very large or very small valid values remain measurements, not recommendations about structural suitability or aesthetics.
Worked example
With the startup values, the 12 × 8 in picture receives a 2 in mat on every side. The glaze therefore measures 12 + 2 × 2 = 16.00 in high and 8 + 2 × 2 = 12.00 in wide. The inner opening is 12 + 2 × (2 – 0.125 + 0.05) = 15.85 in high and 8 + 2 × (2 – 0.125 + 0.05) = 11.85 in wide. The 1 in border produces an outer frame of 12 + 2 × (2 + 1) = 18.00 in high and 8 + 2 × (2 + 1) = 14.00 in wide. The net molding perimeter is 2 × (18 + 14) = 64.00 in, matching the first-open result and workbook.
Learn more
If the framed object is paper-based, material selection matters as much as size. The Canadian Conservation Institute explains why a window mat can create protective air space in its guidance on matting works on paper. For a broader framing package, including selecting a frame with enough rabbet depth for mat, backing, and glazing, see its guidance on framing works of art on paper.
How the model works
The calculator uses a symmetric mat model: Mat height applies equally to the top and bottom, while Mat width applies equally to the left and right. The glaze dimensions are the picture dimensions plus both mat margins. The outer dimensions add the border width on both sides. The inner-frame calculation treats the rabbet width as the amount the molding overlaps the framed package and the fudge factor as a small per-side clearance allowance.
Glaze = Picture + 2 × Mat · Inner frame = Picture + 2 × (Mat – Rabbet + Fudge) · Outer frame = Picture + 2 × (Mat + Border) · Molding length = 2 × (Outer height + Outer width)
Practical framing notes
Measure the physical artwork rather than relying only on a nominal print size, especially for hand-cut paper or older photographs. Decide whether your mat dimension describes the visible border you want around the image and verify the actual overlap created by your frame profile. The nominal molding perimeter is useful for comparing frame sizes, but a workshop cut list usually needs additional material because every 45° cut consumes stock and because grain, knots, dents, or finishing defects can force recuts. For conservation framing, also verify that the artwork does not touch the glazing and that the frame has enough depth for the full package.