gpt-oss-120b vs Mistral Large 3

OpenAI · US  |  Mistral · France · Updated June 2026

Quick verdict

Pick gpt-oss-120b for self-hostable on a single 80gb h100 gpu via mxfp4 or configurable reasoning depth (low/medium/high). Pick Mistral Large 3 for open-weight (apache 2.0), self-hostable or strong multilingual performance. On a tight budget at scale, gpt-oss-120b is the value pick.

gpt-oss-120b (OpenAI, US) and Mistral Large 3 (Mistral, France) line up two different AI ecosystems against each other — a comparison that is as much about cost philosophy and openness as raw capability. gpt-oss-120b is openAI's open-weight 117B-parameter MoE reasoning model (5.1B active) that runs on a single 80GB GPU and approaches o4-mini on reasoning, coding, and tool use. Mistral Large 3 is france's frontier contender — strong multilingual model with European data residency. They diverge most on price and context window — each quantified below from the models' real specs.

Key differences at a glance

Side-by-side specs

Specgpt-oss-120bMistral Large 3
ProviderOpenAI (US) Mistral (France)
ReleasedAugust 5, 2025 December 2, 2025
Context window131K (~197 pages) 256K (~384 pages)
Price (in/out)Open weight (self-host / free) $0.5/$1.5 per 1M tokens
Open weight?Yes — self-hostable Yes — self-hostable
Modalitiestext, code text, image, code
SWE-Bench Verified62.4% Not published
MRCR v2 @ 1MNot published Not published

Who wins what

Self-hostable on a single 80GB H100 GPU via MXFP4

gpt-oss-120b

A core design strength of gpt-oss-120b.

Configurable reasoning depth (low/medium/high)

gpt-oss-120b

A core design strength of gpt-oss-120b.

Agentic tool use, function calling, and code execution

gpt-oss-120b

A core design strength of gpt-oss-120b.

Open-weight (Apache 2.0), self-hostable

Mistral Large 3

A core design strength of Mistral Large 3.

Strong multilingual performance

Mistral Large 3

A core design strength of Mistral Large 3.

Efficient inference

Mistral Large 3

A core design strength of Mistral Large 3.

Lowest cost at scale

gpt-oss-120b

At Open weight (self-host / free), it is the cheaper of the two — the gap dominates the bill on high-volume workloads.

Largest single-prompt input

Mistral Large 3

Its 256K window is about 2× larger, fitting roughly 384 pages in one prompt.

Which should you pick?

A cost-sensitive startup shipping high volume

gpt-oss-120b

At Open weight (self-host / free) it undercuts Mistral Large 3, and on millions of tokens that margin decides the monthly bill.

Someone analysing very long documents or codebases

Mistral Large 3

Larger 256K window fits more in one prompt.

Anyone whose priority is self-hostable on a single 80gb h100 gpu via mxfp4

gpt-oss-120b

It is specifically built for that.

Anyone whose priority is open-weight (apache 2.0), self-hostable

Mistral Large 3

That is its strongest area.

An enterprise with regional data-residency rules

gpt-oss-120b or Mistral Large 3

Origin (US vs France) affects where data is processed and which compliance regime applies — check the provider's terms for your region.

gpt-oss-120b: where it fits

OpenAI's open-weight 117B-parameter MoE reasoning model (5.1B active) that runs on a single 80GB GPU and approaches o4-mini on reasoning, coding, and tool use. Released August 5, 2025 by OpenAI, it is built for self-hostable on a single 80GB H100 GPU via MXFP4, configurable reasoning depth (low/medium/high), agentic tool use, function calling, and code execution, and full chain-of-thought visibility for debugging.

Its trade-offs are real: text-only, no image, audio, or video input, and 131K context and 5.1B active params trail the largest frontier closed models. As an open-weight model, its running cost is your own hardware rather than a per-token fee.

Mistral Large 3: where it fits

France's frontier contender — strong multilingual model with European data residency. Released December 2, 2025 by Mistral, it is built for open-weight (Apache 2.0), self-hostable, strong multilingual performance, efficient inference, and function calling.

Its trade-offs: smaller context than US/China frontier, and less benchmark coverage. At $0.5 in / $1.5 out per million tokens, it sits in the budget price band.

The bottom line for this matchup

This is less "which is smarter" and more "which ecosystem fits." gpt-oss-120b (US) and Mistral Large 3 (France) differ on pricing philosophy, data-residency, and tooling as much as on raw scores. gpt-oss-120b is the cheaper option, which matters at volume. The pragmatic move is to run one real task through both and judge the outputs against your own constraints — including where your data is allowed to be processed.

Want both gpt-oss-120b and Mistral Large 3 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.

See pricing

Frequently asked questions

Is gpt-oss-120b or Mistral Large 3 better for coding?

Public SWE-Bench figures are not available for Mistral Large 3, so the honest test is your own repository — run an identical real bug through both. By design, gpt-oss-120b leans toward self-hostable on a single 80gb h100 gpu via mxfp4 while Mistral Large 3 leans toward open-weight (apache 2.0), self-hostable, and that positioning usually predicts which feels better on your codebase.

Which is cheaper, gpt-oss-120b or Mistral Large 3?

gpt-oss-120b is cheaper — Open weight (self-host / free) vs $0.5/$1.5 per 1M tokens.

Which has the bigger context window?

Mistral Large 3 — 256K vs 131K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.

Can I use both gpt-oss-120b and Mistral Large 3 together?

Yes — a multi-model platform like LumiChats gives you gpt-oss-120b, Mistral Large 3 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.

Which is newer, gpt-oss-120b or Mistral Large 3?

Mistral Large 3 — released December 2, 2025, about 4 months after gpt-oss-120b.

Related comparisons

Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.