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Head-to-head comparison

gpt-oss-120b vs o4 Mini

gpt-oss-120b (OpenAI) and o4 Mini (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 22 September 2026

As of 22 September 2026, o4 Mini holds the stronger ModelCap Index position (#107 vs #132); gpt-oss-120b is 7.3× cheaper per output token ($0.60/1M vs $4.40/1M); o4 Mini offers the longer context window (200K vs 131K tokens); and gpt-oss-120b ships open weights.

Which should you choose?

Choose gpt-oss-120b if…

  • API cost matters — $0.60/1M output tokens against $4.40/1M, about 7.3× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.15/1M against $1.10/1M.
  • you want to self-host: gpt-oss-120b ships open weights while o4 Mini is api only.
  • you want provider choice — 20 listed API providers against 1.
  • AA τ²-Bench Telecom is your yardstick — 65.8% against 55.6%.
  • AA Humanity's Last Exam is your yardstick — 19.6% against 16.5%.
  • you want the more recently listed model — gpt-oss-120b was listed 5 August 2025, o4 Mini 16 April 2025.

Choose o4 Mini if…

  • you want the stronger overall ModelCap Index position — #107 against #132 (51.6 vs 43.3 points).
  • you need the longer context window — 200K tokens against 131K.
  • Arena coding is your yardstick — 1433 against 1391.
  • SWE-bench is your yardstick — 45.0% against 26.0%.

gpt-oss-120b vs o4 Mini: specs, pricing and context

Specification comparison of gpt-oss-120b and o4 Mini
Fieldgpt-oss-120bOpenAIo4 MiniOpenAI
ModelCap Index position#132#107
Index score43.351.6
EvidenceMeasuredMeasured
Input price / 1M tokens$0.15$1.10
Output price / 1M tokens$0.60$4.40
Context window131K tokens200K tokens
Max output tokens66K100K
API providers listed201
Weight accessOpen weightsAPI only
Input modalitiesTextImage, Text, File
First listed5 August 202516 April 2025
PublisherOpenAIOpenAI

Evidence: 3 public benchmark observations across 3 boards · 3 public benchmark observations across 3 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: gpt-oss-120b vs o4 Mini

Public benchmark boards where gpt-oss-120b or o4 Mini has a published result
Boardgpt-oss-120bo4 MiniLeads
Arena codingArena (LMArena)13911383–139814331426–1440o4 Mini
ARC-AGI-2ARC Prize Foundation—6.1%HighOnly one result
SWE-benchSWE-bench (Princeton / SWE-agent team)26.0%45.0%o4 Mini
BFCL V4UC Berkeley (Gorilla)—53.2Function callingOnly one result
AA Intelligence IndexArtificial Analysis11.6intelligence-index:v4.3:high—Only one result
AA τ²-Bench TelecomArtificial Analysis65.8%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="gpt-oss-120b (high)":reasoning=true55.6%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="o4-mini (high)":reasoning=truegpt-oss-120b
AA Humanity's Last ExamArtificial Analysis19.6%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="gpt-oss-120b (high)":reasoning=true16.5%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="o4-mini (high)":reasoning=truegpt-oss-120b

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

gpt-oss-120b vs o4 Mini: common questions

Is gpt-oss-120b better than o4 Mini?

o4 Mini ranks higher on the ModelCap Index as of 22 September 2026: #107 against #132. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is gpt-oss-120b cheaper than o4 Mini?

gpt-oss-120b is cheaper on output tokens: $0.60/1M against $4.40/1M. Input tokens are $0.15/1M for gpt-oss-120b and $1.10/1M for o4 Mini. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $0.60 for gpt-oss-120b versus $4.40 for o4 Mini. gpt-oss-120b costs 86.4% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, gpt-oss-120b or o4 Mini?

o4 Mini has the larger context window: 200K tokens against 131K.

Which is better for coding, gpt-oss-120b or o4 Mini?

Arena coding: gpt-oss-120b 1391, o4 Mini 1433 — o4 Mini leads. SWE-bench: gpt-oss-120b 26.0%, o4 Mini 45.0% — o4 Mini leads.

Are gpt-oss-120b and o4 Mini open-weight models?

gpt-oss-120b: Open weights. o4 Mini: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run gpt-oss-120b and o4 Mini?

ModelCap currently lists 20 API providers for gpt-oss-120b and 1 for o4 Mini, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this gpt-oss-120b vs o4 Mini comparison?

Every figure comes from the sealed ModelCap dataset published 22 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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