Picture Frame Sizes: Standard US and Metric Chart

A frame’s size is the size of the picture it holds, not the size of the frame. An 8×10 frame holds an 8 × 10 inch picture; the frame itself is bigger by the width of its molding. Keep that in mind and the rest of frame sizing is simple.

Standard US frame sizes

Frame size	In cm	Shape (ratio)	Common use
4 × 6 in	10.2 × 15.2	2:3	Standard photo prints
5 × 7 in	12.7 × 17.8	5:7	Photos, cards, invitations
8 × 10 in	20.3 × 25.4	4:5	Portraits, small art prints
8.5 × 11 in	21.6 × 27.9	17:22	Certificates, US Letter documents
11 × 14 in	27.9 × 35.6	11:14	Art prints; 8×10 with a mat
12 × 12 in	30.5 × 30.5	1:1	Square prints, records, scrapbook pages
16 × 20 in	40.6 × 50.8	4:5	Large photos; 11×14 with a mat
18 × 24 in	45.7 × 61.0	3:4	Posters, art prints
24 × 36 in	61.0 × 91.4	2:3	Full-size posters

To see a size for real, the actual size viewer shows a 4×6 photo on your screen at true size once calibrated.

Metric frame sizes

Outside North America, frames come in centimeters and ISO paper sizes. They’re close to US sizes but not the same, so a US print can rattle in a metric frame or not fit at all.

Metric frame	In inches	Closest US size
10 × 15 cm	3.9 × 5.9	4 × 6
13 × 18 cm	5.1 × 7.1	5 × 7
20 × 25 cm	7.9 × 9.8	8 × 10
A4 (21 × 29.7 cm)	8.27 × 11.69	8.5 × 11 (A4 is longer)
30 × 40 cm	11.8 × 15.7	12 × 16
40 × 50 cm	15.7 × 19.7	16 × 20
50 × 70 cm	19.7 × 27.6	20 × 28

How mats change the size

A mat is the card border between the picture and the frame. A matted frame is sized for the outside of the mat, so it holds a smaller picture than its size suggests:

• 8×10 frame with a mat → 5×7 photo
• 11×14 frame with a mat → 8×10 photo
• 16×20 frame with a mat → 11×14 photo

The window in the mat is cut ½ inch smaller than the picture in each direction, so the picture overlaps the mat by ¼ inch on every side. A 5×7 photo sits behind a 4½ × 6½ inch opening; an 8×10 behind a 7½ × 9½ opening. If a small part of the image must stay visible, such as a signature near the edge, ask for a larger opening.

Which frames crop your photo?

Frames have different shapes, so a photo may not fill one without cropping. Cameras usually take photos in 3:2, and phones in 4:3. Here’s how much of the photo’s long side is trimmed to fit (for the 4:3 phone photo in a 4×6 frame, the short side is trimmed instead):

Frame	3:2 camera photo	4:3 phone photo
4 × 6	No crop	11% of the short side
5 × 7	7%	5% of the short side
8 × 10	17%	6%
8.5 × 11	14%	3%
11 × 14	15%	5%
12 × 12	33%	25%
18 × 24	11%	No crop
24 × 36	No crop	11% of the short side

So a camera photo fits 4×6 perfectly but loses about a sixth of its length in an 8×10. A phone photo fits 18×24 exactly and needs little trimming for 8×10 or 11×14. Printing services let you choose the crop before ordering.

Pixels you need for a sharp print

For a sharp print at 300 pixels per inch, multiply the frame size by 300: a 4×6 print needs 1200 × 1800 pixels, a 5×7 needs 1500 × 2100, and an 8×10 needs 2400 × 3000. The pixels to inches converter works this out for any size.

Measuring a frame you already have

Take the backing out and measure the opening at the back (the rabbet), where the glass sits, with a ruler. It’s usually about ⅛ inch larger than the nominal size so the picture slides in easily; an 8×10 frame might measure 8⅛ × 10⅛ inches. Measure the picture you want to use, too: a print that’s even ⅛ inch too big won’t fit.