Official specs from Steam

Mount & Blade: Warband system requirements

Minimum and recommended PC specs as listed by the developer on Steam. Native macOS version available. Native Linux build available.

Minimum

OS *Windows® XP
ProcessorIntel Pentium 4 2.0 GHz or AMD 2.5 GHz
Memory512MB RAM
Graphics3D graphics card with 64MB RAM
Hard Drive100 MB available space
SoundStandard audio

Recommended

OS *Windows XP or greater
ProcessorIntel Core Duo 2.0 GHz or AMD Athlon 64 X2 3600+
Memory1GB RAM
GraphicsNVIDIA GeForce FX 5200, ATI Radeon 9600, or better
Hard Drive100MB available space
SoundStandard audio

macOS minimum

OSOS X version El Capitan 10.11, or later.
ProcessorIntel Mac
Memory1 GB RAM
GraphicsNVIDIA GeForce 8600M / ATi Radeon 2400 or better
Hard Drive1 GB available space
SoundStandard audio

FAQ

What graphics card do I need for Mount & Blade: Warband?

Minimum: 3D graphics card with 64MB RAM. Recommended: NVIDIA GeForce FX 5200, ATI Radeon 9600, or better.

How much RAM does Mount & Blade: Warband need?

Mount & Blade: Warband needs 512MB RAM at minimum, 1GB RAM recommended.

How big is Mount & Blade: Warband?

Mount & Blade: Warband requires 100 MB available space.

Does Mount & Blade: Warband run on Mac or Steam Deck/Linux?

Yes, there is a native macOS version. A native Linux build is available.