About this tool
Change image width and height by exact pixels, percentage or a practical preset. Aspect-ratio controls help prevent accidental stretching, while Fit and Fill make the trade-off between showing the whole image and covering a fixed canvas explicit. Resizing changes pixels; the DPI calculator only estimates print dimensions.
How to use Image Resizer
Choose the source
Add supported images and check their current pixel dimensions before choosing a larger or smaller canvas.
Set the geometry
Choose pixels, percentage or a preset. Keep the aspect ratio locked, or deliberately choose Fit, Fill or Stretch for a different shape.
Check the framing
Choose Resize Images, then download and verify dimensions and crop position. Enable enlargement only if you accept its detail limits.
When should you use this tool?
- Meeting exact upload dimensions
- Creating a smaller web or email copy
- Fitting an image into a fixed canvas
- Estimating print size from pixels and DPI
Example: fit a 4:3 photo into a 16:9 thumbnail
A 4000 × 3000 landscape photo must become a 1600 × 900 thumbnail. The shapes differ. Unlock the aspect ratio to enter both target dimensions, then choose Fit or Fill rather than accidentally stretching the subject.
- Enter a 1600 × 900 pixel canvas and choose Fit to keep every edge of the photo.
- Alternatively choose Fill and crop, then select a crop position that keeps the subject inside the frame.
- Download and check the 1600 × 900 result. If a face or label is cut off, change the crop position or return to Fit.
The geometry behind Fit, Fill and print size
Aspect ratio = width ÷ height. Fit scale = min(target width ÷ source width, target height ÷ source height); Fill uses max instead. Rounded output dimensions must be whole pixels. Print width in inches = pixel width ÷ pixels per inch. For example, 1800 pixels at 300 PPI correspond to 6 inches (15.24 cm). The DPI-labelled calculator estimates size; it does not write print-resolution metadata.
| Mode | Scaled image | Visible consequence |
|---|---|---|
| Fit | 1200 × 900 | 200-pixel padding at each side |
| Fill | 1600 × 1200 | 150 pixels cropped at top and bottom |
| Stretch | 1600 × 900 | Width scales by 0.4, height by 0.3: shapes distort |
Common mistakes to avoid
- A 50% resize halves each dimension, leaving 25% of the original pixel count.
- Changing the DPI estimate does not create detail or change the exported pixel dimensions.
- Enlargement is opt-in, and interpolation cannot recover an unreadable label.
Accuracy and limits
At most 8192 pixels on either output side and 40 million output pixels. Rounding can alter the aspect ratio slightly at very small sizes. Fit padding and transparent pixels depend on output format and background; JPG has no transparency.
Pixels, percentages and common resolutions
Enter exact dimensions, resize by percentage, or choose presets such as Full HD, 2K, 4K, YouTube thumbnail and Google Play feature graphic.
Fit, crop or stretch
Fit keeps the whole image visible, Fill and crop covers the requested canvas, and Stretch deliberately forces the exact width and height.
Enlargement and image detail
Increasing pixel dimensions cannot restore detail that is missing from the original. Enlargement is disabled until you deliberately allow it.
Dimensions, file size and print size
Pixel dimensions determine the raster resolution, while format and quality affect file size. The DPI calculator estimates physical print size without claiming to write metadata.
Related guides
Private browser-based processing
Your files are decoded and encoded locally in the browser. ConvertHop does not upload image contents, filenames, previews, EXIF or GPS data to a conversion service. Analytics and advertising remain disabled.
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Frequently asked questions
Can I resize to exact pixels?
Yes. Set width and height, or choose presets including Full HD, 2K, 4K and platform sizes.
What is the difference between Fit and Fill?
Fit keeps the entire image visible and may add padding. Fill covers the full output and crops excess.
Does changing DPI add detail?
No. DPI only translates pixel dimensions into an approximate print size. It does not create pixels or restore detail.
Can I prevent distortion?
Yes. Keep the aspect ratio locked, or use Fit or Fill when the target canvas has a different shape.
Does enlarging improve quality?
No. Enlargement interpolates more pixels but cannot recover detail missing from the source.