OpenAI
GPT-5 Flagship
Previous-generation OpenAI flagship for complex workflows
Model Summary
Family
GPT-5
Version
5.0
Parameters
2100B (est.)
Parameter counts for closed models are estimates; vendors rarely publish exact sizes.
VRAM Requirements by Quantization
Memory needed to serve GPT-5 Flagship for inference, including a 20% overhead for activations and KV cache.
| Precision | VRAM needed | Smallest single GPU that fits |
|---|---|---|
| INT4 (4-bit) | 1173.47 GB | Multi-GPU required |
| INT8 (8-bit) | 2346.93 GB | Multi-GPU required |
| FP16 (16-bit) | 4693.87 GB | Multi-GPU required |
| FP32 (32-bit) | 9387.73 GB | Multi-GPU required |
Recommended GPU Configurations
Cheapest on-demand configurations to serve GPT-5 Flagship at 8-bit (2347 GB VRAM).
19x AMD Instinct MI250X
2432 GB total VRAM · CDNA 2 · multi-node
~$47.50/h
147x NVIDIA T4
2352 GB total VRAM · Turing · multi-node
~$73.50/h
13x AMD Instinct MI300X
2496 GB total VRAM · CDNA 3 · multi-node
~$78.00/h
Quick GPU Planning
Use the calculator pre-filled with this exact version to estimate memory, speed, and compute requirements in a few clicks.
Access Pre-filled CalculatorFrequently Asked Questions
How much VRAM do you need to run GPT-5 Flagship?
With an estimated 2100B parameters, GPT-5 Flagship needs roughly 2347 GB of VRAM in 8-bit (INT8), 1173 GB in 4-bit, and 4694 GB in FP16, including a 20% overhead for activations and KV cache.
Which GPUs can run GPT-5 Flagship?
At 8-bit quantization, the most cost-effective option is 19x AMD Instinct MI250X (2432 GB combined VRAM, around $47.50/hour on-demand). Higher-end cards like the NVIDIA B200 or AMD MI355X reduce the GPU count needed.
Can GPT-5 Flagship run on a single GPU?
No. Even in 4-bit, GPT-5 Flagship exceeds the memory of any single current GPU, so a multi-GPU cluster is required.
How much does it cost to serve GPT-5 Flagship in the cloud?
Renting 19x Instinct MI250X costs on the order of $47.50/hour, i.e. about $34,675/month running 24/7. Actual prices vary by provider and commitment; spot and reserved capacity can be significantly cheaper.
Deploy on a GPU cloud
Rent 19x Instinct MI250X by the hour instead of buying hardware.
