PC requirements

Quake 4 System Requirements

Quake 4 needs at least Intel® Pentium® 4 2.0 GHz or AMD® Athlon® XP 2000+ processor or higher, 512MB RAM and 100% DirectX® 9.0c compatible 64MB 3D hardware accelerated video card required graphics.

Verified Sources: Steam store listing
Quake 4 minimum and recommended PC specifications
Component Minimum
Operating system Windows® XP
Processor Intel® Pentium® 4 2.0 GHz or AMD® Athlon® XP 2000+ processor or higher
Memory 512MB RAM
Graphics 100% DirectX® 9.0c compatible 64MB 3D hardware accelerated video card required
Storage 2.8GB of uncompressed free hard disk space (plus 400MB for Windows® swap file)
Not sure how your PC compares? Use the Can I Run It checker — pick your CPU and GPU and it tells you which column you land in.

Other platforms

Quake 4 is also available on these systems, where hardware is fixed and no per-PC check is needed:

Quick answers

Running Quake 4 on PC

Can my PC run Quake 4?
Compare your CPU, GPU and RAM against the minimum column below. If your parts match or beat every minimum row, the game will launch — though you may need to lower settings. Matching the recommended column is what gets you 60fps at 1080p.
How much storage does Quake 4 need?
2.8GB of uncompressed free hard disk space (plus 400MB for Windows® swap file)