CPU Stress Test

When you press start, the tool creates one Web Worker for every thread you selected. A Web Worker is a separate JavaScript thread that the browser is free to schedule on its own CPU core, which is what makes a genuine multi-core test possible inside a web page. Each worker immediately enters an endless loop of work: it scrambles a number with bit-shifting operations, takes a square root, and repeats, mixing the integer and floating-point math that real programs rely on.

Every fifth of a second, each worker reports how many operations it finished since its last report. The page adds up these reports across all workers and converts the total into millions of operations per second. It keeps a short rolling window of recent samples for the current reading, a running total for the average, and remembers the single best second as the peak, since one instantaneous number on its own can be misleading.

The number of logical cores comes from the hardwareConcurrency value your browser exposes, which counts hardware threads rather than physical cores. When you stop the test, every worker is terminated instantly and the average throughput per thread is compared against a typical browser target to produce a plain-language score.

The workload never touches your files, network, or hardware settings. It is ordinary JavaScript math running in the browser sandbox, and closing the tab ends it completely.