Use case

Compress images for a website

Reduce image file sizes to improve page load speed — without uploading your images to a third-party server.

Compression runs in your browser — images never leave your device.

Compress image — files stay local How local processing works →

Why image size matters for web performance

Images are typically the largest assets on a web page and the most common cause of slow load times. A single unoptimised photograph can be larger than all the CSS, JavaScript, and HTML on the same page combined.

Reducing image file size directly reduces the amount of data the browser needs to download before the page appears. For users on slower connections or mobile data, this difference is significant. Search engines also factor page speed into ranking, so optimised images have an indirect SEO benefit.

The goal is the smallest file size that preserves acceptable visual quality at the display size you are using. A 4000 × 3000 px photo displayed at 800 × 600 px carries three times more data than necessary even before compression.

Choosing the right format

Format	Best for	Compression type
JPEG	Photography, hero images	Lossy — smaller files, some quality loss
PNG	Screenshots, logos, icons	Lossless — exact pixels, larger files
WebP	Any web image	Lossy or lossless — typically smallest at same quality

Compress image — files stay local

Common questions

What image formats can be compressed?

JPEG and PNG are supported. JPEG compression reduces file size by adjusting quality. PNG compression uses lossless optimisation, which typically gives smaller reductions but preserves exact pixel values.

What quality setting should I use for web images?

For most web images, a quality setting of 75–85% is a good starting point. At this range, visual degradation is minimal and file sizes are significantly reduced. Hero images and photography where quality is critical can stay at 85–90%. Icons and diagrams often compress well at 70–80%.

Should I convert to WebP for my website?

WebP typically achieves smaller file sizes than JPEG or PNG at comparable quality. If your website supports it (most modern browsers do), converting to WebP is a worthwhile step. Filecraft's image converter supports JPEG and PNG to WebP conversion.

Are images uploaded during compression?

No. Compression runs entirely in your browser. Images are read into browser memory, compressed locally, and written to your device. Nothing is transmitted to Filecraft's servers.

Batch convert images →How local processing works →Compress a PDF for email →

Why image size matters for web performance

Format

Best for

Compression type

JPEG

Photography, hero images

Lossy — smaller files, some quality loss

PNG

Screenshots, logos, icons

Lossless — exact pixels, larger files

WebP

Any web image

Lossy or lossless — typically smallest at same quality