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Image Optimisation Savings Calculator

Work out image optimisation savings instantly with clear inputs, formula shown and shareable results.

About Image Optimisation Savings Calculator

Savings are applied as the typical size reduction for the target format at visually equivalent quality, then multiplied by the number of images on the page. AVIF roughly halves JPEG weight but encodes slowly, which is why WebP remains the pragmatic default for large image libraries.

Formulas

New weight

new KB = original KB x (1 - typical saving)

Page saving

total saved = saving per image x number of images

Worked example

With the default values below, Image Optimisation Savings Calculator returns Saved per image of 270.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Current image weightminimum 0.1 KB
900 KB
Target formatone of WebP (about 30% smaller than JPEG), AVIF (about 50% smaller), JPEG at lower quality (about 40% smaller)
WebP (about 30% smaller than JPEG)
Images on the pageminimum 1
12

Results

Saved per image
270.0 KB
New image weight
630.0 KB
Typical saving for this format
30.0%
Saved across all images on the page
3,240.0 KB

Step by step

  1. 1Values used
  2. 2New weight
  3. 3Page saving
  4. 4Saved per image= 270.0 KB
  5. 5New image weight= 630.0 KB
  6. 6Typical saving for this format= 30.0
  7. 7Saved across all images on the page= 3,240.0 KB

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Image Optimisation Savings figure worked out?

new KB = original KB x (1 - typical saving). Savings are applied as the typical size reduction for the target format at visually equivalent quality, then multiplied by the number of images on the page.

Why does this matter?

AVIF roughly halves JPEG weight but encodes slowly, which is why WebP remains the pragmatic default for large image libraries.

What do I need to enter?

Enter current image weight, target format, images on the page. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

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