# Why are 2:3 standard frame sizes not exactly 2:3?

I have some photos in a standard 2:3 aspect ratio that I want to print and put in a frame. However, all the options for printing as well as the standard frame sizes I found are not exactly in a 2:3 ratio, but slightly off.

For example, here are some standard sizes I found that are suggested by both the photo printing service I use and the frame sizes that are available at some online stores:

• 9cm x 13cm
• 11cm x 17cm
• 13cm x 18cm

But those aren't actually 2:3 ratios. The exact length for the long side should be `9 x 1.5 = 13,5`, `11 x 1.5 = 16,5` and `13 x 1.5 = 19.5`. So why are the ratios off like that? I first thought it's because of the bleeding or something like that, but that doesn't make sense either since the actual ratio for those formats vary and the cutoff differs between them (as well as between the long and the short edge).

So what's up with those standard sizes? And how will they fit in the frame? I had some pictures printed out at 11x17 cm, I've measured them now and they are actually more like 11.2x17 cm, which is pretty much 2:3 ratio. What's up with that?

For example, for this purpose I would like to get the 13cm frame & print. However, between the mentioned 13x18 format and an actual 2:3 format is some disparity. So what will happen? Will the print service cut the long edge by 1.5 cm? Will the short edge be slightly shorter? Or what?

So what's up with those standard sizes?

The dimensions you mention are very close to the B7 (88x125mm), C6 (114x162mm), and B6 (125x176mm) standard sizes, respectively. So I think you're just seeing European standards in action. There's some useful method to their madness -- each size in a given series is 1/2 the size of the next larger size.

And how will they fit in the frame?

It's a good bet that if Europe has standard sizes for paper, they also have standard-sized frames to fit those paper sizes. You should be able to find frames that fit your prints.

So what will happen? Will the print service cut the long edge by 1.5 cm?

You'll need to either crop your image to the right aspect ratio, or print the entire thing with white bands on two sides. It's just like printing an image at 5x7in or 8x10in, which people do all the time in the US.

• Exactly, these are sizes of photographic paper sold in Europe. The frames just reflect paper sizes on the market. One exception is the 11x17, typical size is 11x15 (approx. equivalent of 4x6") – MirekE Sep 16 '16 at 14:41
• This is only partially true. Most of the photographic paper sizes in Europe are translated measures from the traditional paper sizes in inch. E.g., 10 cm × 15 cm is in reality almost always 4" × 6". And, concerning aspect ratios, the printing machines usually work on paper rolls and will adapt the length of the paper to the image's aspect ratio (sometimes the customer can decide), e.g., a 13 cm × 18 cm from a 2:3 image will be more a 13 cm × 19.5 cm. – Chris Sep 16 '16 at 16:05
• @Chris It's hard to tell if you're responding to my answer or MirekE's comment. The question here is essentially why the provider doesn't offer something with a 2x3 aspect ratio such as 10x15cm, and why they offer these seemingly oddball sizes instead. I don't claim that no providers in Europe print at 2x3 aspect ratio, but the sizes the OP lists do seem to correspond pretty closely to the B7, C6, and B6 standard sizes. – Caleb Sep 16 '16 at 16:30
• Actually, at least in Sweden, "10x15 cm" was for a very long time the most common size for prints from film (it was what you got unless you told the lab to give you some other size). I checked some old prints that go back to the early 1990s or so and measured them as 102x153 mm, for as close to a perfect 2:3 ratio as I'm able to measure. – user Sep 16 '16 at 19:26
• The European standard paper sizes all have the same aspect ratio, based on the square root of 2: `1.414`. That's very close but not the same as the 3:2 ratio of `1.5`. The situation is the U.S. is much more confusing, it seems every standard picture size has a different aspect ratio! – Mark Ransom Jul 17 '17 at 22:37

Predating photography, the Dutch automated paper-making and became a major supplier of paper products. The paper making machines outputted a large sheet of paper that was sized to the span of a typical workman’s outstretched arms. This sheet was then cut down to make various sizes of writing and drawing paper. The Dutch marketed an 8 X 10 drawing paper that was very popular in England. The 8 X 10 inch was typically cut in quarters to make 4 X 5 sheets, and these were cut down to make 3 ½ X 5 inch sheets. The 8 X 10 was also cut in half making two 5 X 8 inch sheets. These were trimmed to 5 X 7 inch, a more pleasing aspect ratio. You should research the “Golden Rectangle” an aspect ratio handed down by pre-renaissance artists. Photo prints sizes naturally followed these popular artist formats.

The first practical photographic process was the Daguerreotype, an image on metal plates. Initially the camera accepted a plate that measured 6 ½ X 8 ½ inches (165 X 216 mm). The camera back could be re-positioned to allow partial plate imaging. The sizes offered were: Half Plate 4 ½ X 5 ½ inches (114 X 130mm), Quarter Plate 3 ¼ X 4 ¼ inches (83 X 108mm), Sixth Plate 2 ¾ X 3 ¾ inches (70 X 83mm), Ninth Plate 2 X 2 ½ inches (51 X 64mm). These sizes became the international standard for photo prints and picture frames.

In the early 1900’s, Thomas Edison was working on a motion picture and viewing system for Penny Arcades. His team, headed by W K L Dickson and William Heise, bargained with George Eastman (Kodak) for film. Kodak was making 70mm wide long rolls for the Brownie camera. The Edison team purchased the 70mm long rolls and slit them into two rolls of 35mm. The motion picture camera required that the film had edge perforation to engage sprockets teeth. These smoothly transported the moving film in the camera. The sprocket holes were spaced on both edges of the film. The space between for an image was 24mm. The Edson team set the format at 24mm long 18mm height. This became the initial motion picture aspect ratio.

In 1913, Ernst Leitz tasked his chief engineer Oskar Barnack to invent a still camera to accept the now popular 35mm socketed film. The camera was to held primarily in the horizontal position to Barnack set the frame length twice the 18mm = 36mm and retained the 24mm as the image height. The result was a frame that measured 24mm height by 36mm length. This was the Leica marketed 1924.

Also, keep in mind that for most of photographic history, the final output was a paper print made from a semitransparent negative. The film needed to we wider than the actual image size as this lip or opening was needed supported the film during exposure. Likewise, a negative gate was required to support the negative by the edges during the printing exposure. The camera’s film mask and the enlarger negative mask extended past the image, it cut off about 2% of the frame, both top and bottom and sides.

That’s just some of the rest of the story regarding popular photo image sizes. .

• This is all interesting, but I don't think you've answered the OP's question. – Caleb Sep 16 '16 at 16:31

I have some photos in a standard 2:3 aspect ratio that I want to print and put in a frame. However, all the options for printing as well as the standard frame sizes I found are not exactly in a 2:3 ratio, but slightly off.

If you want to print and frame at your own chosen aspect ratio, you can do two things:

1. Print smaller picture on a larger paper. For example, print 10x15 on a 13x18 paper. The white border around your image is necessary in some frames where the photograph is mounted to the front mate anyways.
2. Use custom sized framing mats or even custom sized frames. A framing shop should be able to help with both.

Lots of stuff is "not exactly ..." because of historical compromises. Many of these involved adapting something new to something old.

• This answer doesn't add anything useful. – Harry Harrison Sep 17 '16 at 8:21