Benchmark Builder

Free online tool. All processing is client-side. No signup needed.

How to Use the Benchmark Builder

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Benchmark Builder?

A Benchmark Builder measures your computer's CPU performance through JavaScript-based computation tests — mathematical operations, array processing, string manipulation, and cryptographic operations. The result is a relative performance score that lets you compare your device to others or track performance changes over time (after upgrades, thermal throttling, or software changes). While not as precise as native benchmarks (Geekbench, Cinebench), a browser-based benchmark is universally accessible and requires no installation.

How Does It Work?

Click 'Run Benchmark' and the tool executes a suite of CPU-intensive JavaScript tests: (1) Prime Number Calculation (finding all primes up to N via Sieve of Eratosthenes), (2) Array Sorting (sorting large random arrays), (3) String Operations (concatenation, regex matching, encoding), (4) Math Operations (trig, log, and floating-point calculations), (5) JSON Parse/Stringify (data structure processing), (6) Hash Computation (SHA-256 hashing of data chunks). Each test is timed and scored against a baseline. The final score is a weighted composite.

Formula

Benchmark Suite Components:\n\nTest 1: Sieve of Eratosthenes (primes up to 10M)\nScore = 1 / (iterations per second)\n\nTest 2: Array sorting (1M random integers)\nScore = sorts per second\n\nTest 3: String processing (regex, concat, encoding)\nScore = operations per second\n\nTest 4: Floating-point math (trig + log loops)\nScore = calculations per second\n\nTest 5: SHA-256 hashing (1MB chunks)\nScore = MB hashed per second\n\nOverall Score = Geometric Mean of sub-scores\n(Baseline: 1000 = modern mid-range desktop in 2026)\n\nSingle-threaded: all tests run on main thread\nMulti-threaded (optional): uses Web Workers

Who Uses This Tool?

• Comparing device performance before and after hardware upgrades
• Testing browser JavaScript engine performance (V8 vs. SpiderMonkey vs. JavaScriptCore)
• Detecting thermal throttling on laptops and phones
• Comparing different devices (desktop, laptop, tablet, phone)
• Fun: bragging rights and friendly competition

Pro Tips

• Close other tabs and applications before running — background processes reduce available CPU and skew results. Run the benchmark 2-3 times and average
• Browser choice affects score: Chrome V8, Firefox SpiderMonkey, and Safari JavaScriptCore have different JS optimization strategies. Scores are browser-relative, not absolute
• For consistent comparisons, always run the same browser version and close other applications. Scores can vary 5-15% between runs due to OS scheduling
• Mobile devices will score much lower than desktops despite having 'fast' processors due to thermal/power constraints and ARM vs. x86 architecture

Frequently Asked Questions about Benchmark Builder

Is a JavaScript benchmark accurate?

It accurately measures JavaScript engine performance within the browser, which reflects real-world web app performance. It is NOT a comprehensive system benchmark — it doesn't test GPU, disk I/O, or multi-core scaling well. For system benchmarking, use native tools (Geekbench, Cinebench).

Why does my score vary between runs?

Background processes, OS thread scheduling, thermal throttling, and JavaScript garbage collection timing all introduce variance. Always run 2-3 times and take the average. Let your device cool down between runs to avoid thermal throttling.

Free online Benchmark Builder — no signup, 100% client-side processing. All data stays in your browser.