Tab Memory Estimator
A playful rule of thumb, not a lab measurement; real tab weight varies wildly, and browsers park background tabs to save RAM. All readings stay on your device.
How it works
仕組みHow many tabs is too many for this machine? Where the browser allows it, this tool reads the live JavaScript heap of the current tab (memory used, the ceiling it’s allowed, and a sparkline of the last few minutes) alongside your device’s reported memory class and CPU threads. From that it offers a cheerfully rough “comfortable tab budget”, assuming a typical tab weighs 100-300 MB. It’s an estimate, clearly labelled as one, but it’s computed from your actual hardware, which is something no generic listicle about tab hoarding can do.
The performance.memory readout is a non-standard Chromium extra, so only Chrome, Edge, and friends expose live heap numbers. Firefox and Safari simply don’t offer an equivalent to web pages. On those browsers the tool still shows device memory and CPU threads where available, and the tab budget still works from those.
That’s deliberate. navigator.deviceMemory is rounded to a coarse scale and capped at 8 GB precisely so it can’t become a sharp fingerprinting signal. It tells sites your device’s rough class, not its true spec, so treat the tab budget on big machines as a floor rather than a ceiling.
Less than they used to. Modern browsers freeze or discard inactive tabs: Chrome’s Memory Saver and Safari’s tab suspension reclaim most of a sleeping tab’s RAM and reload it when you return. Heavy pages left in the foreground, like busy web apps with live feeds, are the real budget-eaters.