All frames are measured using the inside dimensions, height and width. So if you have a 30x40cm image, you need to order a 30x40cm frame. IIt's common to assume the dimensions relate to the outer edges.

For example, if you're looking for a frame for a 4x6 inches picture and choose a frame with a 2-in wide molding, the outer dimensions of the frame will be 6x8 inches. Traditionally, the most common frame sizes have been 4x6, 5x7 and 8x10. These look great in any room in your house or office!

Although when it comes to picture frames, there is no one-size-fits-all. However, the far most popular picture frame sizes are: 5x7", 8x10", 10x12", 12x16", 16x20", 20x24" and 24x36.

The most common standard poster sizes are 18x24, 24x36, and 27x40 inches. These sizes are popular because they are easy to find frames for, and they are large enough to make an impact without being too expensive.