🏠 New in High Baseline Support: Resource size

September 27, 2025

caniuse · mdn · [spec]([‘https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-decodedbodysize’, ‘https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-encodedbodysize’, ‘https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-transfersize’])

The decodedBodySize, encodedBodySize, and transferSize properties of the PerformanceResourceTiming API reports the size of resources loaded.

Source features

• api.PerformanceResourceTiming.decodedBodySize [mdn]
• api.PerformanceResourceTiming.encodedBodySize [mdn]
• api.PerformanceResourceTiming.transferSize [mdn]