FRAME SIZE LAB
PICTURE FRAME SIZE GUIDE

20 × 24 frame size

A 20×24-inch print has a 5:6 ratio. A nominal 20×24 frame can also be used as the outer-board reference for smaller artwork, including a 16×20 print.

Calculate a frame for this 20 × 24 print ↗All picture frame sizes

Reviewed 2026-09-11 · Inches first · Original dimensional calculations

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 × 24 inches in cm, mm and both orientations

Nominal sheet dimensions; conversions are calculated, not tolerance allowances.
MeasurementPortrait / listed orderLandscape / reversed order
Inches20 × 2424 × 20
Centimeters50.8 × 60.9660.96 × 50.8
Millimeters508 × 609.6609.6 × 508
Aspect ratio5:66:5

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 20 × 24 sheet

Compare a frame described for a 20 × 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.

20×24 is wider in proportion than 16×20

16×20 is 4:5, while 20×24 is 5:6. Scaling a 16×20 image to 20 inches wide makes it 25 inches tall; filling a 20×24 print removes 1 inch of that scaled height. A mat around an existing 16×20 sheet is a different operation: it preserves the sheet dimensions and covers only the specified edges.

A full 16×20 print in a 20×24 board

The board adds 4 inches in each direction, so the sample 15.75×19.75 window produces equal 2.125-inch borders. This is the smaller-artwork use of the 20×24 frame label. To mat a full 20×24 sheet, look at the separate larger-board table below instead.

Comparing 24×28 and 24×30 outer boards

Both boards add 4 inches in width. The first adds 4 inches in height and gives equal borders; the second adds 6 and gives taller top/bottom borders. The visible frame lip can reduce those modeled border widths, and the listed outside molding dimensions will be larger still.

With a mat around a full 20 × 24 print

These centered examples use ⅛ inch overlap on each artwork edge, producing a 19.75 × 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.

Borders are measured from the window to the outer board edge; the frame lip can hide part of them.
Outer board / nominal frame (in)Window (in)Left / right border (in)Top / bottom border (in)
24 × 2819.75 × 23.752.1252.125
24 × 3019.75 × 23.752.1253.125
24 in nominal board width19.75 × 23.75MAT OPENING · IN
20 × 24 artwork modeled inside a 24 × 28 outer board. The outline represents the nominal board boundary, not the frame molding.

Window = artwork − 2 × overlap
Centered border = (outer board − window) ÷ 2

Open this 24 × 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 20 × 24 outer board

This reverses the question: keep the nominal frame at 20 × 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.

Centered examples on a 20 × 24-inch outer board, with ⅛-inch overlap per artwork edge.
Full artwork (in)Window (in)Left / right border (in)Top / bottom border (in)
16 × 2015.75 × 19.752.1252.125
12 × 1611.75 × 15.754.1254.125

Before comparing a frame listing

Questions about 20 × 24 frames

Is 20×24 the same as 50×60 cm?

The exact inch conversion is 50.8×60.96 cm. The nearby metric format is smaller; it is not an exact nominal match.

Can an 18×24 sheet go into a 20×24 mat board?

The sheet shares the board’s nominal height. A positive visible window border does not create extra board beyond the full sheet in that direction. Ask a supplier about a suitable larger board rather than inferring support from window math alone.

Compare related frame sizes

Return to the frame-size directory · Work backward from a frame you already own · Understand mat terminology