Photo Mat Size: Find the Frame From Your Picture
Type the size of your picture and the border you want on the sides and top, and read the frame size a photo mat needs. The example is a 20 × 30 cm picture in a 30 × 40 cm frame.
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- Frame size
- Mat opening
- Side borders
- Top border
- Bottom border
How to find a photo mat size
The page opens in the picture and border mode, with a 20 × 30 cm print. Only the boxes for that mode are shown.
- Choose cm or inches. Type the size of the print you will mount, as it comes from the lab, without any white edge.
- Type the overlap. The starting value is 0.5 cm, which hides half a centimetre of the print on each side behind the mat.
- Type the border you want on the sides and the top. For the 20 × 30 cm print, 5.5 cm gives a 30 × 40 cm frame.
- Read the frame size, then the opening. The frame size is the window the mat has to fill, so it is the size to buy or to cut to.
- Tick Weight the bottom if the picture should sit a little higher. The wanted border stays on the top and the bottom grows by half as much again.
Where the 30 × 40 cm example comes from
The example starts from a 20 × 30 cm print. A 5.5 cm border on the sides and top, with the 0.5 cm overlap, gives a 30 × 40 cm frame, which is the size in the frame list on the parent calculator.
The border is the number that changes the frame most. Each extra centimetre of border adds two centimetres to the width and two to the height, one on each side.
Frame sizes for one 20 × 30 cm print
| Picture | Overlap | Border on sides and top | Bottom | Frame |
|---|---|---|---|---|
| 20 × 30 cm | 0.5 cm | 5.5 cm | 5.5 cm | 30.0 × 40.0 cm |
| 20 × 30 cm | 0.5 cm | 10.5 cm | 10.5 cm | 40.0 × 50.0 cm |
| 20 × 30 cm | 0.5 cm | 6.0 cm | 6.0 cm | 31.0 × 41.0 cm |
| 20 × 30 cm, weighted bottom | 0.5 cm | 6.0 cm | 9.0 cm | 31.0 × 44.0 cm |
The print size is the starting point
The frame is built around the print. The opening is the print minus twice the overlap, so a 20 × 30 cm print with a 0.5 cm overlap has a 19 × 29 cm opening. Every frame size on this page starts from that opening and adds the two borders.
Type the print size you will actually mount. A print that is a centimetre smaller than planned moves the whole frame size by a centimetre.
The border you choose decides the frame
The border is the strip of mat between the visible edge of the opening and the edge of the frame. It is added twice in each direction, so the frame is the opening plus two borders. A 5.5 cm border gives 30 × 40 cm and a 10.5 cm border gives 40 × 50 cm for the same print.
The calculator also checks the border against the overlap. A border narrower than the overlap would show the print past the frame, and the page says so instead of giving a frame.
What the weighted bottom adds
Weighting leaves the width alone and makes the frame taller. The wanted border stays on the top, and the bottom border becomes one and a half times it. With a 6 cm top border the bottom is 9 cm, and the vertical border is 15 cm, so the 29 cm opening needs a 44 cm frame instead of 41 cm.
Use the weighted bottom when the print is hung on a wall and should look centred. Leave it off when the frame must stay as short as possible.
Tips for better results
- Type the print size as the lab gives it. A file size on your screen is not the same as the printed size.
- Try two borders side by side, such as 5.5 cm and 10.5 cm. The two frames differ by 10 cm in each direction.
- Keep the overlap at 0.5 cm for a print you will hang behind glass. A wider overlap hides more of the photograph at the edges.
- Use the preview to see how much of the print the mat shows before you order a frame.
- If the frame size is not on the shop list, choose the nearest size and keep the border from the cutting diagram.
Privacy
Your photo, if you add one for the preview, never leaves your device. The numbers are worked out in your browser, and nothing is uploaded or stored.
Frequently asked questions
How big a frame does a photo need?
Take the picture width, subtract twice the overlap and add twice the border; do the same for the height. For a 20 × 30 cm photo with a 0.5 cm overlap and a 5.5 cm border, that is 30 × 40 cm.
Which border should I choose for a photo?
The calculator takes the border you type and does not pick one. A 5.5 cm border gives a 30 × 40 cm frame for a 20 × 30 cm print, and a 10.5 cm border gives 40 × 50 cm, so the border is the choice that sets the size.
Should I measure the file or the print?
Measure the print you will order, because the print is what sits behind the mat. A file that is 3000 pixels wide can print at many sizes, so the frame follows the printed size and not the number of pixels.
Does the calculator need my photo to work?
No. The sizes you type give the frame. The optional photo only fills the preview, and it is read in your browser and not sent anywhere.
What does the weighted bottom do to a photo frame?
It makes the frame taller, not wider. With a 6 cm top border the bottom becomes 9 cm, so a 20 × 30 cm print needs a 31 × 44 cm frame instead of a 31 × 41 cm one.
Related tools and guides
- Picture Mat Calculator: Opening, Borders and Cutting Diagram: Work out the mat opening and borders for a frame and picture, or the frame size from a picture and a border.
- Mat Board Calculator in Inches or Centimetres: A mat board calculator for one job: an 8 × 10 in picture in a 16 × 20 in frame, with the opening and every border in inches and a cutting diagram to cut from.
- Gallery Wall Planner: frames at real sizes: Lay out a gallery wall with ready grids or your own frame sizes, then read the measurements to hang it.
- Work out how large your photo can print: Convert pixels and print dimensions; change JPEG DPI tags.
- Print a Poster on Multiple Pages: Split a large image into paper sheets for a poster, with overlap and a printable PDF.
- Make a contact sheet of your photos: Print a page of thumbnails with captions and EXIF lines as a PDF or page images.
- I Built the Tools I Kept Looking For as a Photographer: Why these calculators run in your browser instead of on a server.