GPT-OSS 120B Q4 VRAM Requirement and Ollama Model Size
GPT-OSS 120B Q4 needs 70GB minimum VRAM, 80GB optimal VRAM, and 128GB+ system RAM for a safer Ollama run. Top-20 curated profile from ollama.com popular list.. Caveat: Estimated values are placeholders unless marked measured..
Hardware Snapshot
| Family | GPT-OSS |
|---|---|
| Scenario | reasoning |
| License scope | open-weight |
| Quantization | Q4 |
| VRAM minimum | 70GB |
| VRAM optimal | 80GB |
| Best local GPU | Dual RTX 4090 (model parallel) |
| Cloud fallback | A100 80GB |
| Updated | 2026-02-24 |
| Data status | Estimated baseline (pending measurement) |
| Ollama source | Library reference (verified: 2026-02-24) |
| Ollama tag | gpt-oss:120b |
| Popularity | Open-Weight Large |
| Category | Reasoning / Large |
Benchmark Anchors
| Hardware | Expected tok/s |
|---|---|
| RTX 3090 24GB | 1.9 |
| RTX 4090 24GB | 2.6 |
| A100 80GB | 4.6 |
Quick Answers
- How much VRAM does GPT-OSS 120B Q4 need?
- GPT-OSS 120B Q4 needs about 70GB minimum VRAM and 80GB optimal VRAM for a safer local run target.
- Can GPT-OSS 120B Q4 run on an RTX 3090 24GB?
- Not as a comfortable local target. GPT-OSS 120B Q4 needs about 70GB minimum and 80GB optimal VRAM, so cloud or larger local GPUs are safer.
- What is the Ollama command for GPT-OSS 120B Q4?
- Use ollama run gpt-oss:120b. Check the Ollama tag gpt-oss:120b before running.
- What is the approximate Ollama model size for GPT-OSS 120B Q4?
- GPT-OSS 120B Q4 uses the gpt-oss:120b Ollama tag. Treat the Q4 120 profile as smaller than the runtime VRAM budget; use 70GB minimum VRAM and 80GB optimal VRAM as the safer sizing numbers.
- How much system RAM does GPT-OSS 120B Q4 need in Ollama?
- Plan for at least 128GB system RAM alongside 70GB minimum VRAM and 80GB optimal VRAM. More RAM helps if layers spill to CPU or if you run multiple models.
- What is the RAM vs VRAM requirement for GPT-OSS 120B Q4?
- GPT-OSS 120B Q4 should be sized by GPU VRAM first: 70GB minimum and 80GB optimal. System RAM should be at least 128GB so Ollama has room for CPU-side layers, context, and the surrounding app process.
- What is GPT-OSS 120B Q4 VRAM usage on an RTX 3090?
- GPT-OSS 120B Q4 is not recommended for an RTX 3090 24GB target. The page estimates 70GB minimum and 80GB optimal VRAM, with spill risk marked as high without a larger GPU or cloud.
- Which LocalVRAM profiles share the gpt-oss:120b Ollama tag?
- LocalVRAM tracks these profiles for the same Ollama tag or model family: GPT-OSS 120B Q4 (Q4, 70GB min/80GB optimal); GPT-OSS 120B Q5 (Q5, 80GB min/82GB optimal); GPT-OSS 120B Q8 (Q8, 74GB min/84GB optimal); GPT-OSS 120B FP16 (FP16, 80GB min/92GB optimal); GPT-OSS 120B CLOUD (CLOUD, 70GB min/78GB optimal). Use the table on this page to compare quantization and VRAM targets before choosing a run command.
- Is GPT-OSS 120B Q4 benchmark data measured or estimated?
- GPT-OSS 120B Q4 currently uses estimated baseline anchors on this page. Verified benchmark data will replace the estimate after a local hardware run is available.
Ollama Model Size and RAM Notes
| Ollama tag | gpt-oss:120b |
|---|---|
| Run command | ollama run gpt-oss:120b |
| Model size guidance | Q4 quantization, 120 profile; size runtime by VRAM, not download size alone |
| Runtime VRAM target | 70GB minimum, 80GB optimal |
| System RAM planning | 128GB or more when running this tag locally with Ollama |
Download size alone is not a safe runtime budget. Runtime memory also includes KV cache, context length, and GPU layer placement.
Ollama RAM vs VRAM Requirements
| GPU VRAM usage estimate | 70GB minimum / 80GB optimal |
|---|---|
| System RAM requirement | 128GB or more for Ollama runtime headroom |
| RTX 3090 24GB fit | Not recommended |
| CPU spill risk | High without larger GPU or cloud |
| Context warning | Longer context increases KV cache memory, so real VRAM usage can exceed short-prompt estimates. |
For Ollama, VRAM is the first fit check. System RAM matters when layers spill to CPU, when context grows, or when the local app stack runs beside the model.
Available Tag Variants and VRAM Targets
| Profile | Quantization | VRAM target | Ollama tag |
|---|---|---|---|
| GPT-OSS 120B Q4 | Q4 | 70GB min / 80GB optimal | gpt-oss:120b |
| GPT-OSS 120B Q5 | Q5 | 80GB min / 82GB optimal | gpt-oss:120b |
| GPT-OSS 120B Q8 | Q8 | 74GB min / 84GB optimal | gpt-oss:120b |
| GPT-OSS 120B FP16 | FP16 | 80GB min / 92GB optimal | gpt-oss:120b |
| GPT-OSS 120B CLOUD | CLOUD | 70GB min / 78GB optimal | gpt-oss:120b |
Ollama library tags often group multiple quantization choices under one model family. LocalVRAM separates them into VRAM profiles so you can pick the right local target.
Real Hardware Benchmark (RTX 3090)
Real benchmark data not available yet for this tag. Estimated anchors are shown above.
Performance Curve
Reference anchors are baseline estimates. Measured RTX 3090 data is overlaid when available.
Best Hardware for GPT-OSS 120B Q4
- Local run: RTX 3090 (24GB) (Check latest deal) for around 1.9 tok/s on this profile.
- Cloud run: RunPod A100 80GB , about 2.4x the local 3090 speed anchor.
- Alternative cloud: Vast.ai options for flexible spot pricing.
Local vs Cloud Cost Hint
| Mode | 40h / month | 120h / month |
|---|---|---|
| Local power only (3090 baseline) | $2.24 | $6.72 |
| A100 80GB | $102 | $306 |
Related Model Profiles
- GPT-OSS 120B Q5 80GB min, 82GB optimal
- GPT-OSS 120B Q8 74GB min, 84GB optimal
- GPT-OSS 120B FP16 80GB min, 92GB optimal
- GPT-OSS 120B CLOUD 70GB min, 78GB optimal
ollama run gpt-oss:120b More reasoning models More 100b-250b models Benchmark changelog Submit your test result Run on RunPod Try Vast.ai We may earn a commission if you click links on this page.
This page currently uses estimated benchmark baselines. Measured data will replace it after validation.