gpt-oss-120b vs MiMo-V2.5-Pro

OpenAI · US  |  Xiaomi · China · 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 MiMo-V2.5-Pro for complex software engineering (top-ranked on swe-bench pro) or long-horizon autonomous tasks (1,000+ tool calls). On a tight budget at scale, gpt-oss-120b is the value pick.

gpt-oss-120b (OpenAI, US) and MiMo-V2.5-Pro (Xiaomi, China) 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. MiMo-V2.5-Pro is xiaomi's flagship agentic model — autonomous, long-horizon software engineering at a fraction of frontier cost. 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-120bMiMo-V2.5-Pro
ProviderOpenAI (US) Xiaomi (China)
ReleasedAugust 5, 2025 April 22, 2026
Context window131K (~197 pages) 1M (~1,500 pages)
Price (in/out)Open weight (self-host / free) $0.435/$0.87 per 1M tokens
Open weight?Yes — self-hostable Yes — self-hostable
Modalitiestext, code text, image, video, 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.

Complex software engineering (top-ranked on SWE-bench Pro)

MiMo-V2.5-Pro

A core design strength of MiMo-V2.5-Pro.

Long-horizon autonomous tasks (1,000+ tool calls)

MiMo-V2.5-Pro

A core design strength of MiMo-V2.5-Pro.

Strong on GDPVal and ClawEval

MiMo-V2.5-Pro

A core design strength of MiMo-V2.5-Pro.

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

MiMo-V2.5-Pro

Its 1M window is about 7.6× larger, fitting roughly 1,500 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 MiMo-V2.5-Pro, and on millions of tokens that margin decides the monthly bill.

Someone analysing very long documents or codebases

MiMo-V2.5-Pro

Larger 1M 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 complex software engineering (top-ranked on swe-bench pro)

MiMo-V2.5-Pro

That is its strongest area.

An enterprise with regional data-residency rules

gpt-oss-120b or MiMo-V2.5-Pro

Origin (US vs China) 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.

MiMo-V2.5-Pro: where it fits

Xiaomi's flagship agentic model — autonomous, long-horizon software engineering at a fraction of frontier cost. Released April 22, 2026 by Xiaomi, it is built for complex software engineering (top-ranked on SWE-bench Pro), long-horizon autonomous tasks (1,000+ tool calls), strong on GDPVal and ClawEval, and agent-framework integration.

Its trade-offs: benchmark rankings are largely vendor-stated, and limited Western adoption and tooling. At $0.435 in / $0.87 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 MiMo-V2.5-Pro (China) 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 MiMo-V2.5-Pro 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 MiMo-V2.5-Pro better for coding?

Public SWE-Bench figures are not available for MiMo-V2.5-Pro, 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 MiMo-V2.5-Pro leans toward complex software engineering (top-ranked on swe-bench pro), and that positioning usually predicts which feels better on your codebase.

Which is cheaper, gpt-oss-120b or MiMo-V2.5-Pro?

gpt-oss-120b is cheaper — Open weight (self-host / free) vs $0.435/$0.87 per 1M tokens.

Which has the bigger context window?

MiMo-V2.5-Pro — 1M vs 131K, about 7.6× larger. Useful only if the model actually reasons over the full window, which not all do.

Can I use both gpt-oss-120b and MiMo-V2.5-Pro together?

Yes — a multi-model platform like LumiChats gives you gpt-oss-120b, MiMo-V2.5-Pro 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 MiMo-V2.5-Pro?

MiMo-V2.5-Pro — released April 22, 2026, about 9 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.