Quick Answer
Open the Device Information tool - it reports your available logical CPU cores using the browser's hardware concurrency figure, which reflects how many parallel execution threads your browser can actually use, not necessarily the exact physical core count listed on your processor's spec sheet.
Logical Cores vs. Physical Cores: Why the Number Can Look Different
Some CPUs support simultaneous multithreading (Intel Hyper-Threading is one example), which lets a physical core expose more than one logical processor. A 6-core CPU with two threads per core may therefore expose 12 logical processors, but this is not universal: some cores expose one thread, and hybrid CPU designs can have different core types. The browser's hardwareConcurrency value is an estimate of logical processors available to the page, not a direct count of physical cores, and browsers may limit or adjust the value for privacy or resource management.
Checking This When Shopping for or Comparing Computers
This is also a handy quick check if you're evaluating a computer you're considering buying secondhand, or trying to verify what's actually inside a prebuilt machine without opening it up or trusting a listing's description. Comparing the reported figure against the seller's claimed CPU model's known specs (searching the exact CPU model name online shows its official core/thread count) is a fast sanity check that the machine's actual hardware matches what's being advertised.
Step-by-Step: Checking Your Reported Core Count
- Open the Device Information tool and note the reported core count.
- Compare it against your CPU's known physical core count (checkable via your OS's Task Manager, Activity Monitor, or the manufacturer's spec sheet for your exact CPU model).
- If the reported number is higher than the physical core count, compare it with the exact CPU model's logical processor specifications; SMT can explain the difference, but core designs vary.
- If the numbers match exactly, that alone does not prove SMT is unsupported or disabled. Check the CPU's official specifications and your operating system's processor details.
- For a broader performance picture beyond just core count, pair this with the CPU Benchmark tool to see actual single-core processing speed.
How to Interpret the Results
- Reported cores roughly double your known physical core count - possible on CPUs with SMT enabled, but compare against the exact processor model because core/thread layouts vary.
- Reported cores exactly match physical core count - not enough information by itself to determine whether SMT is supported or disabled; check the CPU specifications and OS details.
- Reported cores seem unexpectedly low for your known CPU - some browsers cap the maximum reported hardware concurrency value for privacy/fingerprinting reasons, similar to the device memory cap, so very high core-count workstation CPUs may not show their true full figure through this API.
Why This Number Is Capped on Some High-End Systems
Similar to device memory reporting, hardware concurrency can be part of a device's fingerprint when combined with other details, so some browsers apply a cap to the maximum reported value on very high core-count systems as a privacy measure. This mainly affects workstation and server-class CPUs with unusually high core counts rather than typical consumer desktop or laptop processors, which may report a reduced value depending on browser, operating system, and privacy/resource policies.
What This Number Is Actually Used For
Websites use this figure mainly to decide how many parallel worker threads to spin up for computationally heavy tasks - things like in-browser video editing, complex data processing, or certain games and simulations that can meaningfully benefit from splitting work across multiple threads. A site with access to more reported cores can make smarter decisions about how much parallel work to schedule without risking overwhelming a lower-powered device, which is the main practical reason this API exists at all.
FAQ
Does a higher core count always mean better browser performance?
Not directly for everyday browsing, which is usually more dependent on single-core speed and memory. More
cores matter mostly for specific parallel workloads like video encoding or heavy computational tasks running in the browser.
Why would Hyper-Threading be disabled on my system?
Sometimes it's disabled in BIOS/UEFI for specific compatibility or security reasons, or on certain
budget/mobile CPU variants where the manufacturer doesn't include the feature at all.
Does this number change if I close other applications?
No - hardware concurrency reflects the total available logical cores on your system, not how many are
currently free or in use by other applications.
Is this the same as how many cores a specific website is actually using right now?
No, this only reports how many cores are available for a website to potentially use; it's up to that specific
site's own code whether it actually uses multiple threads at all.