Reference squares: 1 wide (4 squares down). Drawing squares: 5 wide.
Scaling in proportion
To enlarge or reduce a picture without stretching it, both sides must change by the same factor. If a photo is 6 inches wide and 4 inches tall and you want it 30 inches wide, the factor is 30 ÷ 6 = 5, so the height becomes 4 × 5 = 20 inches. The calculator does this division and multiplication for you, and also shows the scale as a percentage, which is what copiers and print dialogs ask for.
It works with any unit, including pixels, centimetres, inches or grid squares, so you can use it to plan a mural from a sketch, resize an image for a frame, enlarge a sewing or woodworking pattern, or work out how big a cross-stitch design needs to be. Keep every value in the same unit and the answer will be in that unit too.
From proportion to grid
Artists often combine proportional scaling with the grid method. Divide the reference into a number of equal squares across, then divide your drawing surface into the same number across. The calculator shows both square sizes: on a 6-inch reference with six squares across, each square is 1 inch; on a 30-inch drawing, each square is 5 inches. Copy one square at a time and the proportions take care of themselves.
If you are working from a photo, the add grid to image tool draws the grid on the picture for you and prints a matching labelled grid for your paper. For printed grids at a set square size, use grid drawing paper.
Common sizes and ratios
Photos are usually 3:2 (6 × 4, 12 × 8 inches) or 4:3 (phone cameras), A-series paper is about 1.414:1, US Letter is 11:8.5, and widescreen images are 16:9. When the ratio of your picture and your frame differ, decide which side matters most and let the calculator tell you how much the other side will be cropped or padded.
Frequently asked questions
Which unit should I use?
Any unit, as long as every box uses the same one: inches, centimetres, pixels or even grid squares. The answer comes back in that unit.
How is the scale percentage worked out?
It is the new size divided by the original size, times 100. Enlarging a 6-inch-wide picture to 30 inches is a scale of 500%; reducing it to 3 inches is 50%.
What does the aspect ratio tell me?
The ratio of width to height in lowest terms, for example 3:2 for a 6 × 4 photo. Any size with the same ratio keeps the picture's shape without cropping or stretching.
How do I use the grid result?
Divide your reference into the number of squares across shown, then draw the same number of squares across your paper at the drawing-square size. Copy the picture square by square.
Last updated · About us