20 × 20 frame size
A 20×20-inch frame is square at the nominal insert. The same outer-board label can describe a mat around a smaller square or rectangular picture.
Artwork is the full sheet. Nominal frame size is the stated insert reference. The visible opening is the area left after the frame lip or mat covers the edges. Actual frames, mats, rabbets and listed openings vary by manufacturer; these dimensions do not guarantee fit, preservation, hanging safety, load capacity or compatibility.
20 × 20 inches in cm, mm and both orientations
| Measurement | Portrait / listed order | Landscape / reversed order |
|---|---|---|
| Inches | 20 × 20 | 20 × 20 |
| Centimeters | 50.8 × 50.8 | 50.8 × 50.8 |
| Millimeters | 508 × 508 | 508 × 508 |
| Aspect ratio | 1:1 | 1:1 |
This is a square, so reversing width and height leaves a 1:1 ratio. Product features determine which orientations a particular frame supports. A matching ratio preserves shape when scaling an image; it does not make different physical sheet sizes interchangeable.
Without a mat: start with the full 20 × 20 sheet
Compare a frame described for a 20 × 20-inch insert. Measure any printed paper margin as part of that sheet. Do not subtract the front lip from the artwork dimensions unless the supplier explicitly asks for a visible-window measurement. The back opening, depth and clearance must come from the specific product; no universal rabbet allowance is assumed here.
Compare a square print with a rectangular picture
A 16×16 square picture behind a 20×20 board produces equal 2.125-inch borders at the sample overlap. A 12×16 rectangle produces 4.125-inch side borders and 2.125-inch top/bottom borders. This preserves the rectangular picture’s full-sheet dimensions without requiring it to be printed as a square.
A 12×12 image scales to 20×20 in proportion
Both shapes are 1:1, with a scale factor of 5/3 in each direction. The physical print gets larger, but the ratio stays the same. Frame sizing still depends on the final paper dimensions, and the image file’s pixel count remains a separate print-resolution consideration.
20 inches is larger than 50 centimeters
The exact width is 50.8 cm. A frame labeled for a 50×50 cm insert is nominally smaller by 8 mm in each direction. Check a specific product’s dimensional drawing rather than assuming its clearance will cover that difference.
With a mat around a full 20 × 20 print
These centered examples use ⅛ inch overlap on each artwork edge, producing a 19.75 × 19.75-inch window. This is an editable illustration, not a prescribed cut. Board sizes are comparison scenarios, including possible custom dimensions; stock availability is not asserted.
| Outer board / nominal frame (in) | Window (in) | Left / right border (in) | Top / bottom border (in) |
|---|---|---|---|
| 24 × 24 | 19.75 × 19.75 | 2.125 | 2.125 |
| 28 × 28 | 19.75 × 19.75 | 4.125 | 4.125 |
Window = artwork − 2 × overlap
Centered border = (outer board − window) ÷ 2
Open this 24 × 24 mat example in the calculator to change the board or overlap. Some suppliers take artwork dimensions and make their own deduction; others want the final window size.
Smaller artwork inside a 20 × 20 outer board
This reverses the question: keep the nominal frame at 20 × 20, then compare smaller pictures. It is useful when a listing says “matted to” a smaller photo size. These are calculated scenarios, not a claim about an included mat.
| Full artwork (in) | Window (in) | Left / right border (in) | Top / bottom border (in) |
|---|---|---|---|
| 12 × 12 | 11.75 × 11.75 | 4.125 | 4.125 |
| 16 × 16 | 15.75 × 15.75 | 2.125 | 2.125 |
| 12 × 16 | 11.75 × 15.75 | 4.125 | 2.125 |
Before comparing a frame listing
- Confirm the full sheet and the portion of the image that must remain visible.
- Identify the nominal insert, outer mat board and exact cut window separately.
- Request the actual back opening, rabbet depth and manufacturer tolerances. Width and height alone cannot establish suitability for thick artwork.
- Use the listed outside dimensions for a visual gallery layout; these tables do not provide them.
Questions about 20 × 20 frames
Does a full 20×20 print need a custom mat?
A mat requires a larger outer board and a chosen visible window. The 24×24 and 28×28 examples show the geometry; this guide does not establish which cuts or products a supplier stocks.
Is the outside frame also square?
The nominal insert is square. Most symmetrical profiles would produce a square exterior, but actual external dimensions and construction must be verified from the product.
Compare related frame sizes
Return to the frame-size directory · Work backward from a frame you already own · Understand mat terminology