Resource sizeBaseline · Widely available

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

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Mar 27, 2023. Widely available since Sep 27, 2025.

How to use ↓Compare browsers

Browser support

DesktopChrome

1–53Not supported

54+Supportedsince Oct 12, 2016

Current: 155

Edge

12–16Not supported

17+Supportedsince Apr 30, 2018

Current: 154

Firefox

1–44Not supported

45+Supportedsince Mar 8, 2016

Current: 157

Safari

1–16.3Not supported

16.4+Supportedsince Mar 27, 2023

Current: 27

MobileChrome Android

18–53Not supported

54+Supportedsince Oct 19, 2016

Current: 155

Firefox Android

4–44Not supported

45+Supportedsince Mar 8, 2016

Current: 157

Safari iOS

1–16.3Not supported

16.4+Supportedsince Mar 27, 2023

Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN: decodedBodySize.

Feature detection

JS · check before using

if ("PerformanceResourceTiming" in globalThis && "decodedBodySize" in PerformanceResourceTiming.prototype) {
  // PerformanceResourceTiming.decodedBodySize is available
}

Documentation (MDN)

Specification

Sub-features

Support for each part of the feature (3). The overall table above shows when the whole feature works.

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
PerformanceResourceTiming.decodedBodySize	54	17	45	16.4	54	45	16.4
PerformanceResourceTiming.encodedBodySize	54	17	45	16.4	54	45	16.4
PerformanceResourceTiming.transferSize	54	17	45	16.4	54	45	16.4