Official specs from Steam

Borderlands 2 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 SP3
Processor2.4 GHz Dual Core Processor
Memory2 GB(XP)/ 2 GB(Vista)
Hard Disk Space13 GB free
Video Memory256 MB
Video CardNVIDIA GeForce 8500 /ATI Radeon HD 2600
SoundDirectX 9.0c Compatible
Other RequirementsInitial installation requires one-time internet connection for Steam authentication; software installations required (included with the game) include Steam Client, DirectX 9, Microsoft .NET 4 Framework, Visual C++ Redistributable 2005, Visual C++ Redistributable 2008, Visual C++ Redistributable 2010, and AMD CPU Drivers (XP Only/AMD Only)

Recommended

OS *Windows XP SP3/Vista/Win 7
Processor2.3 GHz Quad Core processor
Memory2 GB
Hard Disk Space20 GB free
Video Memory512MB
Video CardNVIDIA GeForce GTX 560 / ATI Radeon HD 5850
SoundDirectX 9.0c Compatible
Other RequirementsInitial installation requires one-time internet connection for Steam authentication; software installations required (included with the game) include Steam Client, DirectX 9, Microsoft .NET 4 Framework, Visual C++ Redistributable 2005, Visual C++ Redistributable 2008, Visual C++ Redistributable 2010, and AMD CPU Drivers (XP Only/AMD Only)

macOS minimum

OS10.12 (Sierra)
Processor2.4 GHz Intel Core 2 Duo (Dual-Core)
Memory4 GB RAM
Hard Disk Space13 GB
Video Memory256 MB
Video CardATI Radeon HD 2600 / NVidia Geforce 8800/ Intel HD 3000
AdditionalMacintosh mouse and keyboard. Borderlands 2 supports both the Xbox 360 wired gamepad AND the PlayStation 3 Dualshock 3 Wireless Controller
NOTICEIt is possible for Mac and PC to become out of sync during updates. Within this short time period, Mac users will only be able to play other Mac users.
NOTICEThis game is not supported on volumes formatted as Mac OS Extended (Case Sensitive)
NOTICEThe following video chipsets are unsupported for Borderlands 2: ATI RADEON HD 2400, NVIDIA 8600m, NVIDIA 9400m, 9600m, Intel Integrated GMA 950, Intel Integrated x3100 NOTICE:The Mac version is only available in English, French, Italian, German, and Spanish.

macOS recommended

OS10.12 (Sierra)
Processor2.2GHz Intel Quad Core
Memory4 GB RAM
Video Memory512 MB
Video CardATI Radeon HD 5750 / NVidia Geforce 650M / Intel HD 4000

FAQ

What graphics card do I need for Borderlands 2?

Minimum: 256 MB. Recommended: 512MB.

How much RAM does Borderlands 2 need?

Borderlands 2 needs 2 GB(XP)/ 2 GB(Vista) at minimum, 2 GB recommended.

How big is Borderlands 2?

Borderlands 2 requires 13 GB free.

Does Borderlands 2 run on Mac or Steam Deck/Linux?

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