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Free Online CPU Benchmark — Test Processor Speed

Relative processing-speed score from in-browser math.

Runs intensive math in your browser for ~8 seconds to estimate relative CPU performance.

How it works

How the browser CPU benchmark works

This benchmark measures how many mathematical operations — prime number generation, array sorting, and hashing — your browser can complete in a fixed time window. The raw count is normalised against a baseline of 1000 to produce your final score. A score of 2000 means the engine performed twice as many operations as the baseline.

Because the test runs entirely in JavaScript, the result reflects the combined performance of your CPU, JavaScript engine, and system state. It is best used as a relative comparison between different browsers on the same machine, or to verify that a laptop's performance is in the expected ballpark.

What affects your score

Thermal throttling

Laptops, especially thin ones, reduce clock speed when they get hot. If your score drops significantly on the second run, try waiting a minute for the system to cool down.

Power mode

Windows "Power Saver" or macOS "Low Power Mode" cap the CPU. Run the test in a "High Performance" or "Balanced" power plan with the charger plugged in.

Background load

Other open tabs, video streaming, or system updates consume CPU time. Close unnecessary applications before benchmarking for a clean reading.

What this benchmark does not tell you

It does not measure single-core vs multi-core directly, GPU compute, memory bandwidth, or native application performance. It is a narrow test of JavaScript math throughput — nothing more. For full diagnosis, use native tools like Geekbench, Cinebench, or your laptop manufacturer's diagnostics.

Related tools

Frequently Asked Questions

What does the CPU benchmark number mean? expand_more
The score is relative to a baseline of 1000. A score of 2000 means the browser's JavaScript engine completed twice as many operations in the same time. It is not a measure of CPU clock speed — it reflects how fast the browser runs math-heavy code on your processor.
Why is my score lower than expected? expand_more
Browser benchmarks are affected by background tabs, thermal throttling, power-saving modes, and browser choice. Run the test with other apps closed, the laptop plugged in, and in a "Performance" power mode for the most accurate result.
Does this measure the same as Geekbench or Cinebench? expand_more
No. Those are native tools that bypass the browser and test raw CPU power directly. This test runs inside JavaScript, which adds overhead and varies between browsers. Use this as a quick sanity check, not a replacement for native benchmarks.
Why is the score different in a different browser? expand_more
Each browser has its own JavaScript engine (V8 in Chrome, SpiderMonkey in Firefox, JavaScriptCore in Safari). The same CPU can score very differently because engines optimize math differently — this is expected.
Should I run the test multiple times? expand_more
Yes. Run 2-3 times and take the median. If the scores vary wildly (more than 20%), thermal throttling or background processes are likely interfering. A stable score is more meaningful than a single peak score.