PC Bottleneck Calculator.
No guessing.

A bottleneck happens when one component in your PC limits the performance of another. In games, your CPU prepares each frame and your GPU draws it. If the CPU finishes its work faster than the GPU can draw, the CPU sits idle waiting — that's a GPU bottleneck. If the GPU finishes drawing faster than the CPU can feed it new frames, the GPU sits idle — that's a CPU bottleneck. A perfectly balanced build keeps both components busy with no idle time, which gives you the highest possible FPS for the parts you own.

The fastest check is to load a game and watch hardware usage with MSI Afterburner or Task Manager. If GPU usage stays at 95–100% and CPU usage is below 70%, you're GPU-bound — your CPU has headroom. If CPU usage is at 100% (or one core is pinned) and GPU usage is below 90%, you're CPU-bound. Bottleneck calculators like this one estimate the same answer from the parts' performance indices without you needing to run the game first, which is useful when planning an upgrade.

There is no single magic number, despite what other calculators claim. A 5–10% imbalance between CPU and GPU is normal and fine — neither part is wasted. A 20%+ imbalance means one component is clearly limiting the other, and you'd see meaningful gains from upgrading the weaker one. We report imbalance as a percentage *and* tell you which component is the limit, not a single context-free number that means nothing.

Yes, significantly. At 1080p the CPU is doing relatively more work per frame, so weak CPUs become the bottleneck. At 4K the GPU is doing massively more work per pixel, so even mid-range CPUs are usually enough — the GPU becomes the limit. Our calculator runs the same parts through three resolutions (1080p, 1440p, 4K) so you can see how the answer changes. A build that's CPU-bound at 1080p can be perfectly balanced at 4K.

For most modern games at 1440p and 4K, the GPU matters more — it's doing the heavy lifting of rendering pixels, lighting, and effects. Budget for the best GPU you can afford, then pair it with a CPU that won't bottleneck it. For competitive esports games (CS2, Valorant, League of Legends) at 1080p with high refresh rates, the CPU becomes more important because frame rates are so high that the CPU has to feed the GPU many more frames per second.

Upgrade whichever one our calculator flags as your bottleneck — that's the component holding back the other. If you're GPU-bound (the most common case at 1440p+), a new GPU gives you immediate FPS gains. If you're CPU-bound (common at 1080p with a recent GPU), a new CPU lifts your frame rate ceiling. Upgrading the part that *isn't* the bottleneck gives you almost no real-world benefit until you also upgrade the limiting part.

For an RTX 4070, a Ryzen 5 7600X or Intel Core i5-13600K is balanced and won't bottleneck — both have CPU pairing pages on this site with measured FPS data. For an RTX 4080, step up to a Ryzen 7 7800X3D or Core i7-13700K. For an RTX 4090, the Ryzen 7 7800X3D is the gold standard for gaming, with the i9-13900K or Ryzen 9 7950X3D as alternatives if you also do heavy productivity work.

RAM speed and capacity can absolutely bottleneck a build — Ryzen CPUs in particular benefit from DDR5-6000 over slower kits, and 16 GB is the minimum for modern games (32 GB is the sweet spot). Slow storage (a SATA SSD vs. an NVMe SSD) causes texture-streaming stutters in open-world games but doesn't change steady-state FPS. An undersized PSU can cause crashes and throttling under load but isn't technically a bottleneck — it's a stability issue. Our PSU recommendation in the result panel accounts for both parts' TDP with appropriate headroom.

Most online bottleneck calculators are based on opaque rules and return suspicious-looking percentages like '67.4% bottleneck' that don't map to anything measurable. Our engine derives a 0–100 performance index for each CPU and GPU from PassMark, Geekbench, and TechPowerUp data, anchored to real-world game benchmarks. We report a verdict (CPU-bound / GPU-bound / balanced), a confidence score based on data quality, and predicted FPS for popular games at three resolutions. Every assumption is documented on our methodology page.

Yes, completely free with no signup. We monetize through Amazon affiliate links on individual CPU and GPU pages — if you buy hardware through one of our links, we earn a small commission at no cost to you. We do not sell data, do not require an account, and use privacy-friendly analytics (Plausible) without cookies or cross-site tracking.