CPU Bottleneck Calculator — CPU vs GPU Pairing Check

Last updated: 24 September 2026 · All math runs in your browser — nothing is uploaded.

How the CPU bottleneck calculator works

A CPU bottleneck calculator answers one question: which part of your PC limits your frame rate — the processor or the graphics card? Pick your CPU and GPU, choose a resolution and workload, and the calculator estimates the maximum FPS each component can sustain, reports the gap as a bottleneck percentage, and tells you which part to upgrade first.

Quick answer: bottleneck % = |CPU FPS cap − GPU FPS cap| ÷ max(CPU FPS cap, GPU FPS cap) × 100, and your effective frame rate is the lower of the two caps. A Ryzen 5 5600 feeding an RTX 4070 at 1080p caps around 145 vs 165 FPS — a 12.1% mild CPU bottleneck; at 4K the same pair flips to a heavy GPU bottleneck, because resolution shifts work onto the graphics card.

Is my CPU bottlenecking my GPU?

If your GPU utilization sits below ~95% while the CPU is maxed, lowering graphics settings barely raises FPS, or performance hardly changes when you drop resolution — yes, the CPU is the limiter. At 1080p with a mid-to-high-end GPU this is common; at 1440p and 4K the GPU usually becomes the bottleneck instead.

How to check CPU bottleneck (3 steps)

1. Choose your processor and graphics card from the curated lists (Intel, AMD and Apple CPUs; NVIDIA, AMD and Intel GPUs).
2. Set the resolution you play at, pick a workload preset — esports, AAA balanced, AAA GPU-heavy or productivity — and enter your target FPS.
3. Read the bottleneck percentage, both FPS caps, which component limits you, whether you hit your target, and the suggested first upgrade — plus a 1080p vs 1440p vs 4K table for the same pair.

CPU bottleneck formulas (FPS caps and percentage)

Every tile on the results panel comes from these formulas:

• CPU FPS cap: cpuCap = CPU performance index × workload multiplier × resolution factor (CPU) × RAM multiplier × background-load factor.
• GPU FPS cap: gpuCap = GPU raster index × workload multiplier × resolution factor (GPU) × background-load factor.
• Bottleneck percentage: bottleneck % = |cpuCap − gpuCap| ÷ max(cpuCap, gpuCap) × 100.
• Effective FPS: effective = min(cpuCap, gpuCap) — the slower component decides what you actually see.
• Resolution factors: 1080p weights the GPU at 1.00 and the CPU at 1.00; 1440p drops the GPU to 0.78 and eases the CPU to 1.04; 4K drops the GPU to 0.52 and eases the CPU to 1.08. Higher resolution = more GPU bottleneck.
• Workload multipliers: esports lets the GPU stretch (×2.00) while the CPU climbs (×1.60); GPU-heavy AAA tightens the GPU (×0.72); productivity switches the CPU to its multi-core index (×3.20).
• Verdict bands: ≤5% well matched · 6–15% mild · 16–30% moderate · >30% severe.

Worked example: Ryzen 5 5600 + RTX 4070 at 1080p

Step 1 — CPU cap: Ryzen 5 5600 index 145 × balanced 1.00 × 1080p 1.00 = 145 FPS. Step 2 — GPU cap: RTX 4070 index 165 × balanced 1.00 × 1080p 1.00 = 165 FPS. Step 3 — bottleneck: |145 − 165| ÷ 165 × 100 = 12.1% — mild, CPU limited. Step 4 — effective FPS: min(145, 165) = 145 FPS, which meets a 144 Hz target exactly. Step 5 — at 4K: CPU 145 × 1.08 = 156.6, GPU 165 × 0.52 = 85.8, so |156.6 − 85.8| ÷ 156.6 = 45.2% GPU bottleneck at 86 FPS — the same pair flips sides when you raise the resolution.

CPU bottleneck vs GPU bottleneck by resolution

CPU bottlenecks dominate at 1080p, where the GPU finishes frames quickly and waits on the processor. GPU bottlenecks dominate at 4K, where millions of pixels swamp the card while the CPU idles. 1440p is the middle ground where well-chosen pairs balance best. Same pair as the worked example (5600 + 4070, AAA balanced):

Resolution	CPU cap	GPU cap	Bottleneck	Limiter
1080p	145 FPS	165 FPS	12.1%	CPU · mild
1440p	151 FPS	129 FPS	14.7%	GPU · mild
4K	157 FPS	86 FPS	45.2%	GPU · severe

That is why “is X bottlenecking Y?” has no single answer — it depends on resolution, settings and the games you play. Run your own pair through the calculator for your exact scenario.

What affects CPU bottleneck in real builds

• Resolution and settings — the biggest lever. 1080p low settings in a competitive title is the classic CPU-bottleneck test; 4K ultra is the GPU-bottleneck test.
• Game engine — CS2, Valorant and sim/strategy titles hammer one or two fast cores; cinematic AAA spreads load across the GPU.
• Target frame rate — chasing 240 FPS makes the CPU the limiter far sooner than playing at 60 FPS with the same pair.
• RAM speed and latency — slow memory costs a few percent of CPU-bound performance, especially on older platforms; DDR5-6000 helps Ryzen 7000/9000 specifically.
• Background load — browsers, launchers, Discord, OBS and antivirus steal CPU time; the advanced field models up to 60% load.
• Clocks, cache and generation — a 7800X3D beats higher-clocked rivals in games thanks to 3D V-Cache; generation-to-generation jumps matter more than core count for gaming.

Frequently Asked Questions