Example
1280 × 720 px (67%)
Image Resize Calculator
Calculate new image dimensions while keeping the aspect ratio instantly in your browser. Free online image resize calculator — find width, height, or percentage.
Enter the values below, then press Calculate (or press Enter). The calculator updates your results instantly. Try different values to see how your inputs change the outcome.
- Original width (px) — enter a numeric amount.
- Original height (px) — enter a numeric amount.
- New width (px, optional) — enter a numeric amount.
- Mode — enter a choice from the options.
- Scale % (when using percentage mode) — enter a numeric amount.
- Review your results — the key output is highlighted, with supporting figures below.
Loading calculator…
Results
New dimensions
| Detail | Value |
|---|---|
| New width (px) | |
| New height (px) | |
| Scale % | |
| New pixel count | |
| Approx file size vs original |
What is this calculator for?
Keep an image’s aspect ratio while scaling to a new width or percentage.
How to Use This Calculator
Enter the values below, then press Calculate (or press Enter). The calculator updates your results instantly. Try different values to see how your inputs change the outcome.
- Original width (px) — enter a numeric amount.
- Original height (px) — enter a numeric amount.
- New width (px, optional) — enter a numeric amount.
- Mode — enter a choice from the options.
- Scale % (when using percentage mode) — enter a numeric amount.
- Review your results — the key output is highlighted, with supporting figures below.
What You'll Need
- Original width (px)
- a numeric amount range 1–∞ · required
- Original height (px)
- a numeric amount range 1–∞ · required
- New width (px, optional)
- a numeric amount range 1–∞ · optional
- Mode
- a choice from the options (Scale by new width, Scale by percentage) · optional
- Scale % (when using percentage mode)
- a numeric amount range 1–500 · optional
About This Calculator
To keep proportions, when you change one dimension you must scale the other by the same factor.
This calculator takes your original width and height plus either a target width or a percentage, computes the matching other dimension, and reports the new pixel count and approximate file-size change.
All math runs locally in your browser.
Worked Examples
Frequently Asked Questions
Why does the height change when I give a width?
To keep the aspect ratio, the height scales by the same factor as the width. Resizing only one dimension would distort the image.
How is file size estimated?
Pixel count scales with width × height. The approximate file-size change is the ratio of new to original pixels, assuming similar compression.