18 × 24 frame size
An 18×24 poster has 3:4 proportions. Use its full sheet size for a nominal frame comparison, then specify any mat window and outer board separately.
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.
18 × 24 inches in cm, mm and both orientations
| Measurement | Portrait / listed order | Landscape / reversed order |
|---|---|---|
| Inches | 18 × 24 | 24 × 18 |
| Centimeters | 45.72 × 60.96 | 60.96 × 45.72 |
| Millimeters | 457.2 × 609.6 | 609.6 × 457.2 |
| Aspect ratio | 3:4 | 4:3 |
Swapping width and height changes portrait to landscape without changing area. 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 18 × 24 sheet
Compare a frame described for a 18 × 24-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.
Same proportions as 12×16, different from 24×36
An 18×24 image is a 1.5-times enlargement of 12×16. A 24×36 rectangle is relatively taller. Fitting an 18×24 image to 24 inches wide produces 24×32, leaving 4 inches of total vertical space on a 24×36 sheet. Printing to fill instead crops the sides of the source image.
When an 18×24 frame contains a smaller poster
“18×24, matted to 12×16” describes an outer board and a smaller picture. It does not promise an 18×24 picture plus a mat. For a full 18×24 sheet, the larger-board table below gives 22×28 and 24×30 geometric examples with equal centered borders at the stated overlap.
A2 artwork is a separate comparison
A2 measures 420×594 mm, while 18×24 inches is 457.2×609.6 mm. The nominal inch board is larger in both directions, but that does not determine the window an included mat provides. Measure the actual sheet and use the calculator if the listing mixes paper names with inch dimensions.
With a mat around a full 18 × 24 print
These centered examples use ⅛ inch overlap on each artwork edge, producing a 17.75 × 23.75-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) |
|---|---|---|---|
| 22 × 28 | 17.75 × 23.75 | 2.125 | 2.125 |
| 24 × 30 | 17.75 × 23.75 | 3.125 | 3.125 |
Window = artwork − 2 × overlap
Centered border = (outer board − window) ÷ 2
Open this 22 × 28 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 18 × 24 outer board
This reverses the question: keep the nominal frame at 18 × 24, 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 × 16 | 11.75 × 15.75 | 3.125 | 4.125 |
| 11 × 17 | 10.75 × 16.75 | 3.625 | 3.625 |
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 18 × 24 frames
What size frame goes around an 18×24 print with a mat?
The answer depends on the desired border. The examples use 22×28 and 24×30 outer boards; neither is a statement of available inventory or a guaranteed fit.
Is 18×24 inches the outside frame size?
Usually the label identifies the insert. Molding changes the external rectangle, which must be obtained separately.
Compare related frame sizes
Return to the frame-size directory · Work backward from a frame you already own · Understand mat terminology