JPEG Quality Estimator

Read the quantisation tables inside a JPEG and estimate the quality it was saved with.

Estimate JPEG quality

JPEG photo

Estimated quality: —

Marker: choose a JPEG to begin

Tables: —

The estimate compares the stored tables with the standard tables at every quality level from 1 to 100.

Choose the JPEG file whose quality you want to estimate.
The tool reads the DQT segment and compares each table with the standard tables.
Read the estimated quality together with the per table error figures.

Common questions about the free online jpeg quality estimator.

Choose the file and the tool compares its quantisation tables with the standard tables at every quality level to find the closest match.

It lists the divisor applied to each frequency block, and coarser divisors mean smaller files with more visible artefacts.

It is a close estimate rather than an exact reading, because some encoders scale the tables in their own way.

Human vision is less sensitive to colour detail, so encoders quantise chrominance more aggressively than luminance.

Around 80 to 90 keeps photos looking clean, while 60 or below is useful when file size matters more than detail.

No. The quantisation tables are read from the file bytes in your browser and nothing is sent anywhere.

The DQT segment is missing or the file is not a complete JPEG, so the quality cannot be estimated.

No. It only reads the stored tables, so your file is never re-encoded or modified.

Yes. The estimator is fully responsive and works in the browser on phones, tablets and desktops.

Last updated: October 10, 2026