Resize a Photo to a Standard Print Size

How it works

Print sizes are measured in inches or centimetres, files are measured in pixels, and this tool converts between the two. Choose your photos, pick the size and the DPI: at 4×6 inches and 300 DPI the output is 1200×1800 pixels, because 300 dots per inch across 4 inches is 1200 dots. Pick 10×15 cm instead and you get 1181×1772 pixels, since 10 cm divided by 2.54 and multiplied by 300 comes to 1181. The result line spells the arithmetic out, so you never have to guess what you are handing the print shop. When the photo's aspect ratio does not match the frame you have two honest choices: crop to fill takes the largest matching area from the centre and lets the edges run off, or fit inside keeps the whole photo and leaves a white or black band along the short edge. Orientation is automatic by default, so a landscape shot lands in a 6×4 frame rather than being squeezed into a portrait one. Select several files at once and they are all prepared with the same settings. The output is always JPG, because that is what kiosks, labs and printer drivers accept without argument.

This tool is also known as 4x6 photo size in pixels, resize photo for printing, 5x7 print size pixels, 10x15 cm photo size, 300 dpi print dimensions, photo print size converter, a4 photo print size.

What is DPI?

DPI means dots per inch, and it describes how densely a print packs dots onto paper. It is not a property of the pixels themselves but the multiplier that ties a pixel count to a physical size. The same 1200×1800 file prints as 4×6 inches at 300 DPI and as 8×12 inches at 150 DPI — the file has not changed, only how tightly the dots are laid down. Photo labs ask for 300 DPI by habit: at reading distance that is roughly the density at which the eye stops picking out individual dots.

What is aspect ratio?

Aspect ratio is the short edge compared with the long edge, and on its own it decides whether a print needs cropping. A 4×6 inch print, 10×15 cm and 20×30 cm all share the 3:2 ratio, so one photo drops into any of them the same way; 5×7 inches is 1.4 and 13×18 cm about 1.385, so a 3:2 photo loses a strip in either. Paper sizes come from another world entirely: the A series is 1.414 and keeps that ratio when folded in half, but no camera has ever shot in it. Checking the ratio before the pixel count is what saves you a surprise at the counter.

What is crop to fill and fit inside?

When a photo's ratio does not match the target frame, exactly two routes remain. Crop to fill takes the largest correctly-shaped area from the centre of the photo and spreads it over the whole frame: no border is left, at the price of a strip lost from the edges. Fit inside places the whole photo into the frame and leaves a flat band along the short edge: nothing is lost, at the price of a visible white or black margin. Documents, screenshots and pictures where the edges matter belong in fit inside; portraits and landscapes usually look better cropped to fill.

What is the difference between 4×6 inches and 10×15 cm?

They are the same print in two measuring systems, and they are almost but not exactly equal. Four inches is 10.16 cm and six inches is 15.24 cm, so a 4×6 print is a couple of millimetres larger on each side than a 10×15 cm one. Both are exactly 3:2, so a photo that fits one fits the other with the same crop. The files differ slightly: at 300 DPI, 4×6 comes to 1200×1800 pixels and 10×15 cm to 1181×1772 — about 1.6 percent apart, invisible on paper but enough for a strict online order form to complain. Order in inches from a US lab and in centimetres from a European one, and use the size the shop's own form lists rather than converting it yourself.

Why doesn't my phone photo fit a 4×6 print?

A 4×6 inch print is exactly 3:2, and so is 10×15 cm and 20×30 cm. Dedicated cameras usually shoot 3:2, but the default on most phones is 4:3. Squeezing a 4:3 frame into a 3:2 print means giving up a strip of roughly 11 percent from the short edge — which is why the top of someone's head disappears at the lab.

5×7 inches and 13×18 cm are harder still: their ratios are 1.4 and about 1.385, matching neither 3:2 nor 4:3. Some cropping or some border is unavoidable there no matter what camera you used. This tool does not hide that; the result line records which route you took.

• Camera shooting 3:2 → 4×6, 10×15 and 20×30 fit exactly
• Phone shooting 4:3 → 4×6 needs cropping
• A4 and A5 → ratio 1.41, cropping needed for both 3:2 and 4:3

Which size and which DPI?

Size depends on where the print will end up; DPI depends on how closely it will be examined. At arm's length the eye resolves detail up to about 300 DPI, which is why labs ask for it. On a framed print viewed from across the room, 150 and 300 DPI are hard to tell apart.

When in doubt stay at 300 DPI. The file is larger, but a printer can always throw pixels away — nobody can put back pixels that were never there.

• Album and wallet prints → 9×13 cm, 300 DPI
• Everyday snapshots → 4×6 in or 10×15 cm, 300 DPI
• Framed on a desk or wall → 5×7 in, 13×18 or 20×30 cm, 300 DPI
• Full page from a home printer → A4, 200-300 DPI
• Test print you will throw away → 150 DPI

Frequently asked questions

My photo doesn't fit 4×6 exactly — why?

Because its aspect ratio isn't 3:2. A 4×6 inch print is exactly 3:2, while most phones shoot 4:3. When the ratios differ there are only two honest options: crop to fill, which trims the edges, or fit inside, which leaves a plain band along the short edge. There is no third setting that both fills the paper and keeps everything, and stretching the photo would distort faces, so this tool never stretches.

Which DPI should I choose?

Choose 300 DPI for anything held in the hand or looked at closely; that is the figure photo labs ask for. If file size is a problem, 200 DPI passes unnoticed on most prints. Keep 150 DPI for proofs and for images that will only be viewed on screen. If your source photo is already small, a higher DPI adds no quality — it only enlarges the pixels you already have.

Can I print a small photo at 20×30 cm?

You can set the size, but the tool cannot invent detail. 20×30 cm at 300 DPI needs 2362×3543 pixels; if your source is 1000×1500 the image is enlarged and the print looks soft. Check the source dimensions in the result line: when the source is smaller than the target, either drop to a smaller print size or accept a lower DPI.

Why is the output always JPG?

Kiosks, photo labs and printer drivers all open JPG without complaint, while PNG and WEBP occasionally get rejected or come back with a colour surprise. So even a PNG source is saved as JPG. Transparent areas are filled with the border colour you picked, because JPG carries no transparency.

Are my photos uploaded anywhere?

No. Scaling and cropping happen inside your browser; the file, its name and its size are never sent to a server. Once the page has loaded, the tool keeps working even if you go offline.

Does a large photo lose detail on the way to 10×15 cm?

When the print frame stays smaller than half the source, a detail-preserving resampling (the Lanczos method) is used: every pixel of the print is the weighted average of all source pixels landing on that spot. Fabric texture, single hairs and lettering on a sign keep their shape instead of turning into a smear. The result line states which path was taken.