Image resize calculator
Pick a source size and a constraint. We compute the matching dimension at the same aspect ratio, plus the percentage scale and final byte estimate.
Output dimensions and ratio will appear here.
FAQ
Why a linear byte estimate?
JPEG / PNG / WebP codecs scale roughly with pixel count, but compression efficiency varies. Linear scaling is a useful upper bound for planning.
What's a typical email image size?
Inline email images max out around 600px wide for non-Retina, 1200px for Retina-friendly. Most email clients clip wider images.
Does this resize the image?
No — it only computes dimensions. Use any image editor or CDN parameters to apply the result.
What about device pixel ratio?
If you want crisp display on Retina, double the target width and let the email client downscale via inline CSS.