Ilford Postcard paper is 4×6″ double weight, Black and White Multicontrast paper. 4×6″ is, as you may remember, your standard photo lab size. When you go to drop off a roll of colour print film to be developed, it comes back printed on 4×6″ colour paper. These days, made by either Fuji or Kodak.

Some people arent too impressed by the humble 4×6″ format, because it’s so common. But, what may not be obvious at first, is that it fits the 35mm format pretty much perfectly.

A 35mm frame is 24x36mm in size. A 4×6″ piece of paper is, in metric, 10x15cm.
The aspect ratio of 35mm is 1.5, and the aspect ratio of 4×6″ is exactly the same – 1.5
To get your aspect ratio, divide the larger side by the smaller size, 36/24 = 1.5. Pretty straight forward, but rather informative.
So you can basically fit everything from a 35mm frame onto a 4×6″ sheet.

Let’s look at the other formats available for Ilford Portfolio paper:

Now this is just for Portfolio paper, Multigrade Deluxe has a much large array of sizes. I’ll post an article covering all the sizes in the Ilford catalogue when I can – it’s a pretty huge catalogue.

But looking at these ratios, you can see that 8×10 doesnt fit 35mm at all well, but despite this it remains the most common size. The world standardised on 8×10″, and for the most part it’s a very appealing size – I have some nice prints in that size on my wall right next to me and I’m very fond of them. But you effectively lose around an inch either side of possible image. Really, 8×12 would be more ideal…11×14 seems like it could be promising though.