Free local photo tool · no upload
Resize image in cm — image size in cm with exact DPI
This photo resizer in cm prepares images for form uploads and printing at a specified physical size. Enter the photo size in cm the form asks for — or switch to millimeters — and the live conversion shows exactly how many output pixels the selected DPI requires.
Resize in CM
Set your image size
Your image stays on your device.
Output preview
Preview scaled to your screen, not actual print size.
Formats, quality and print sizes
JPG and PNG include the selected DPI. Whole pixels are rounded, so the reported physical size can differ slightly. PDF uses the exact requested page size. Screen previews are not a physical ruler.
Up to 50 MB per source free (80 MB with LensUp Pro), 40 megapixels and 10,000 pixels per side for source and output. These are working limits; some devices may need smaller images. SVG, PSD and camera RAW are not supported. HEIC/HEIF and TIFF decode locally; some variants may be unreadable. TIFF uses only the first page; animations use a static first frame.
JPG is lossy and turns transparency white. PNG keeps transparency in Crop or Stretch; Keep whole image flattens all transparency to white and adds margins when shapes differ. Resizing and a higher DPI cannot create missing detail. Presets describe measurements. Check the current form or authority requirements.
How do I do an image resize in cm to an exact size?
Choose the width and height in centimeters, select a DPI, and convert each physical measurement to pixels with px = cm ÷ 2.54 × DPI. LensUp rounds to the nearest whole pixel, then resamples the photo locally in your browser.
| Physical size | Nearest pixel size |
|---|---|
| 3.5 × 4.5 cm | 413 × 531 px |
| 6 × 2 cm | 709 × 236 px |
| 2 × 2 cm | 236 × 236 px |
An online photo resize width and height in cm task has two independent choices: physical pixel dimensions and framing. LensUp keeps those choices visible. It never silently stretches a face, signature or document to a different aspect ratio.
How to resize a photo in centimeters
- Choose one local imagePick a JPG, PNG or other browser-readable image. Processing stays on your device; there is no sign-up, upload or watermark.
- Set centimeters, millimeters and DPIUse a measured preset or enter custom dimensions. The image resize in cm calculation updates immediately with the nearest whole-pixel result.
- Choose how to fit, then exportKeep whole image is the default and adds white margins when needed. Lock original proportions to adjust one side, or choose Crop to fill, then drag or zoom the frame to pick the part you keep. Inspect the preview, then download JPG, PNG or an exact-size PDF.
Measured: are the pixels and the DPI right?
On 12 October 2026 we resized a test chart with a circle in it to three print sizes, leaving the other settings as the tool opens, and checked each file with a script. “Right” means the pixels are within one pixel of the exact size, the DPI is written into the file, and the circle is still round.
| Size asked | What the file says | Right? |
|---|---|---|
| 3.5 × 4.5 cm at 300 DPI | 413 × 531 px, 300 DPI, 23.4 KB, circle round | Yes |
| 35 × 45 mm at 600 DPI | 827 × 1063 px, 600 DPI, 59.6 KB, circle round | Yes |
| 2 × 2 in at 300 DPItyped as 5.08 × 5.08 cm; the tool takes cm and mm | 600 × 600 px, 300 DPI, 36.1 KB, circle round | Yes |
Where it fell short: The chart is landscape and these sizes are not. On Keep whole image, the setting the tool opens with, each file got white bands above and below the chart: on the 3.5 × 4.5 cm file, 111 of its 531 pixels at the top and 111 at the bottom (42% of the height). With the tool’s other setting, Crop to fill, the same size came out at 413 × 531 px with no bands and the chart’s sides cut off. If your photo is not already this shape, choose Crop to fill before you download and move the frame onto the part to keep. We did not check sharpness.
One run per file, in a desktop browser (Chromium). The test files were made for the test; your own photo or scan can come out differently.
How we tested, the raw data, and 3 other cm resizers on the same file →
Resize image in cm and kb as two separate constraints
A physical size and a file-size ceiling measure different things. The centimeter setting determines output pixels at the chosen DPI. The optional KB ceiling searches JPEG quality while preserving those pixel dimensions, and reports the actual final file size.
A low ceiling can require lower JPEG quality. If it cannot be reached while preserving the required pixels, LensUp keeps the dimensions and says the limit was not met. Keep required text, facial edges and signature strokes readable, and compare the result with the source.
Photo resize in cm presets and printing limits
The measured presets include 3.5 x 4.5 cm for a common passport-style form, 6cm x 2cm for an SSC-style signature field, and 2 x 2 cm. These are convenient dimensions, not acceptance rules for every authority. Always follow the current form and leave a safe content margin.
DPI is a conversion scale, not a promise of print-lab color or extra detail. A 3.5 centimeter source enlarged to many pixels may look soft if the original was small. LensUp sets the requested pixel grid and writes the selected DPI into the JPG or PNG file; it cannot recreate detail that the camera never captured.
Image resizer in cm: width × height in centimeters
Set the width and height your form requests in centimeters, then choose its DPI before exporting. For the page’s existing 3.5 × 4.5 cm example at 300 DPI, the nearest-pixel result is 413 × 531 pixels.
Use Keep whole image to preserve the complete photo with margins, or Crop to fill to remove outer areas without stretching. Review the preview before you download.
Common photo sizes in cm
Choose a preset only when its dimensions match the current form. This page offers 3.5 × 4.5 cm, 6 × 2 cm and 2 × 2 cm; they are starting dimensions, not universal acceptance rules.
If the form asks for another size, enter its width and height rather than forcing the photo into a different preset. DPI controls the pixel conversion; it cannot restore missing detail.
Frequently asked questions
How many pixels is 3.5 x 4.5 cm at 300 DPI?
Using the nearest-pixel rule, 3.5 cm becomes 413 px and 4.5 cm becomes 531 px at 300 DPI. The live converter recalculates both values when you choose another DPI.
How do I resize image in cm 6cm x 2cm for a signature?
Choose the 6 × 2 cm preset and confirm the DPI requested by the current form. Keep whole image fits the complete signature with white margins. Use Crop to fill when the outer areas can be removed safely, and zoom in to crop closer around the signature itself.
How do I print at the requested centimeter size?
Download the exact-size PDF and print at Actual size or 100%, with Fit to page disabled. The PDF page uses the requested dimensions; select paper large enough for the image and printer margins. JPG and PNG include DPI metadata but some print apps override it. No physical printer calibration is performed.
Should I crop or stretch when the aspect ratios differ?
Crop to fill preserves proportions but removes outer image areas; drag the frame to keep important content, and zoom in when you want a tighter crop around a face or a signature. Keep whole image adds white margins without cropping. Stretch keeps every pixel but changes proportions, so use it only when that distortion is acceptable.
Can I zoom in to choose which part of the photo is cropped?
Yes. Choose Crop to fill, then use the Zoom slider or drag the frame. Zooming in makes the frame smaller, so less of the original photo is kept and the subject fills more of the result. You cannot zoom out below 1×, because the frame is already as large as the requested shape allows — choose Keep whole image instead to fit the entire photo with white margins.
How do I resize a photo to a specific width and height in cm online?
Choose a photo, enter the form’s width and height in cm, and select its requested DPI. Use Keep whole image to retain the complete photo with margins or Crop to fill to frame it without stretching. Check the preview, then download JPG, PNG or an exact-size PDF.
What is the difference between an image resizer in cm and in pixels?
Centimeters describe physical dimensions; pixels describe the output grid. A centimeter setting needs DPI to determine pixels: px = cm ÷ 2.54 × DPI, rounded to the nearest whole pixel. More output pixels do not recreate detail missing from the source.