design tool
Print scale percentage calculator
The print scale percentage is the new width divided by the old width, times 100: A4 to A3 is 141.4%, A3 to A4 is 70.7%, and A4 to A0 is about 400%. Pick the two sizes to get the percentage, the figure for going back, the density a photo ends up at, and what is lost or left blank when the shapes differ.
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- Runs on your device, nothing is uploaded
- Free, no sign in
- No watermark, no file limit
How it works
- 1
Pick the from size
Choose the size the artwork was made at, or Custom size and type it in millimetres.
- 2
Pick the to size
Choose the sheet it will be printed on. Orientation is matched for you.
- 3
Enter the photo density
Type the DPI of the photos in the original, 300 if it was made for print. The result shows what they drop or rise to.
- 4
Read the percentage
Use the Scale figure in the print dialog or on the copier. If the shapes differ, choose between the fit and the fill figure in the note.
Why A sizes scale by 141%
Every A size has the same proportions, a ratio of 1 to the square root of 2, and each one is exactly half the area of the size above it. Halving the area means each side shrinks by the square root of 2, so going up one size is 141.4% and going down one size is 70.7%. That is why copiers carry those two buttons. Two steps, A4 to A2, is 200%, and four steps, A4 to A0, is 400%. Because the shapes match, nothing is cropped and no white border appears at any of these percentages.
When the shapes differ
US Letter and A4 are not the same shape, and neither is a 36 by 48 inch board and A0. Scaling one to the other is then a choice. Fit uses the smaller of the two ratios, keeps every part of the artwork and leaves a strip of blank paper on two edges; Letter to A4 fits at 97.3%. Fill uses the larger ratio, covers the sheet edge to edge and cuts some artwork off; Letter to A4 fills at 106.3%. The calculator gives both figures and draws them, the fit tinted and the fill dashed in red, so you can see what each one costs.
What scaling does to photos
Vector shapes and live text scale perfectly, but a photo has a fixed number of pixels, and scaling spreads them further apart. A photo at 300 DPI in an A4 document is 212 DPI at A3 and 75 DPI at A0. Large format printers commonly give 150 DPI as their poster minimum, and 300 is the figure for print held in the hand, so the result names which side of each line you land on. Going down in size works the other way, and a scaled down photo gains density that the printer simply discards.
Scaling a flyer up to a poster
An A4 flyer exported from the flyer builder is 2480 by 3508 pixels, 300 DPI on A4. Enlarged to A0 that becomes 75 DPI, half of the usual poster minimum, so small text and photos will look soft from close up. The poster tab builds the board at A0 from the start instead, on its own 1656 by 2340 canvas with poster layouts, and exports A0 portrait at 3312 by 4680 pixels, which is 100 DPI on the sheet, with the type sized for a poster rather than enlarged from a page.
Limits worth knowing
A percentage assumes the same shape, so between different shapes the page shows both options rather than pretending one number works. Bleed is not scaled for you: a 3 millimetre bleed on A4 becomes 12 on A0 at 400%. All of this is arithmetic in this tab; nothing is uploaded and nothing is stored, ever.
Limits
- Percentage scaling assumes the same shape. When the shapes differ, the page gives both the fit and the fill percentage and shows the crop or the blank margin.
- The target is turned to match the original's orientation, as a printer would, so A4 portrait to A3 landscape reads as A4 to A3.
- The A sizes are whole millimetres, so A4 to A0 shows as 400.4% rather than exactly 400.
What it does not do
- It does not resize a file; it gives the percentage to type into a print dialog or a copier.
- It does not check a particular image; enter its density, or use the pixels to inches converter to find it.
- It does not add bleed, which has to be scaled or added separately.
Questions people ask
What percentage do I use to print A4 on Letter paper?
94.1% to fit the whole page on the sheet, which leaves about 9 millimetres of white at each side because Letter is wider and shorter. Most print dialogs call this Fit to page. Printing at 100% instead loses about 18 millimetres of the A4 page's length, which is often where the footer or the page number sits.
How do I enlarge to poster size on a copier?
Most office copiers stop at A3 or tabloid paper, and many cap enlargement at 400%. For a poster, scale the file instead and send it to a large format printer, or use the copier's poster or tiling mode, which prints the enlargement across several sheets to tape together. Either way, check the photo density first, because a big enlargement shows every soft pixel.
Is enlarging by 200% the same as doubling the size?
It doubles the width and the height, which makes the area four times larger. That is why A4 at 200% becomes A2, not A3: A3 is only double the area of A4, and getting there takes 141.4%. Keep the area and side distinction in mind when a printer quotes by the square metre, because the cost grows with the area.
Will text stay sharp when I scale up?
In a PDF with live text or vector shapes, yes, at any percentage, because those are redrawn at the new size. Text that is part of a photo or a flattened image is just pixels, so it softens like any other raster. If a file was exported as one big image, as many design tools do for flyers, all of its text behaves like a photo.
How do I work out a custom scale between two sizes?
Divide the new width by the old width and multiply by 100, then check that the height gives the same figure. If it does not, the shapes differ, and you pick the smaller result to fit or the larger one to fill. Choose Custom size for either side here and type the millimetres to have it worked out with the crop shown.
Build the poster at A0 instead of enlarging
Take what you made here into posters.
Create a poster with OneCraftMore tools like this
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- DPI calculatorEnter a pixel size and a print size and see the sheet drawn at real proportions, the area your file covers sharply, and a plain verdict on whether it will do.
- Resize PDF pages to A4, Letter or any sizeResize PDF pages to A4, Letter, A3, A5, Legal or a custom size. Each page is scaled to fit or fill and centred, with a preview. Nothing is uploaded.
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Background reading: the question page on this.
Written and checked by the OneCraft team. Last checked .