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Head-to-head comparison

gpt-oss-120b vs o3

gpt-oss-120b (OpenAI) and o3 (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, o3 holds the stronger ModelCap Index position (#53 vs #132); gpt-oss-120b is 13.3× cheaper per output token ($0.60/1M vs $8.00/1M); o3 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 $8.00/1M, about 13.3× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.15/1M against $2.00/1M.
  • you want to self-host: gpt-oss-120b ships open weights while o3 is api only.
  • you want provider choice — 20 listed API providers against 1.
  • you want the more recently listed model — gpt-oss-120b was listed 5 August 2025, o3 16 April 2025.

Choose o3 if…

  • you want the stronger overall ModelCap Index position — #53 against #132 (66.5 vs 43.3 points).
  • you need the longer context window — 200K tokens against 131K.
  • Arena coding is your yardstick — 1460 against 1391.
  • SWE-bench is your yardstick — 58.4% against 26.0%.
  • AA τ²-Bench Telecom is your yardstick — 80.7% against 65.8%.
  • AA Humanity's Last Exam is your yardstick — 20.1% against 19.6%.

gpt-oss-120b vs o3: specs, pricing and context

Specification comparison of gpt-oss-120b and o3
Fieldgpt-oss-120bOpenAIo3OpenAI
ModelCap Index position#132#53
Index score43.366.5
EvidenceMeasuredMeasured
Input price / 1M tokens$0.15$2.00
Output price / 1M tokens$0.60$8.00
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 o3

Public benchmark boards where gpt-oss-120b or o3 has a published result
Boardgpt-oss-120bo3Leads
Arena codingArena (LMArena)13911383–139814601454–1467o3
ARC-AGI-2ARC Prize Foundation—6.5%HighOnly one result
SWE-benchSWE-bench (Princeton / SWE-agent team)26.0%58.4%o3
BFCL V4UC Berkeley (Gorilla)—63.1PromptOnly 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=true80.7%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="o3":reasoning=trueo3
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=true20.1%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="o3":reasoning=trueo3

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 o3: common questions

Is gpt-oss-120b better than o3?

o3 ranks higher on the ModelCap Index as of 22 September 2026: #53 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 do not overlap, but the aggregate Index does not predict performance on every task; compare the relevant benchmark configurations before choosing.

Is gpt-oss-120b cheaper than o3?

gpt-oss-120b is cheaper on output tokens: $0.60/1M against $8.00/1M. Input tokens are $0.15/1M for gpt-oss-120b and $2.00/1M for o3. 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 $8.00 for o3. gpt-oss-120b costs 92.5% 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 o3?

o3 has the larger context window: 200K tokens against 131K.

Which is better for coding, gpt-oss-120b or o3?

Arena coding: gpt-oss-120b 1391, o3 1460 — o3 leads. SWE-bench: gpt-oss-120b 26.0%, o3 58.4% — o3 leads.

Are gpt-oss-120b and o3 open-weight models?

gpt-oss-120b: Open weights. o3: 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 o3?

ModelCap currently lists 20 API providers for gpt-oss-120b and 1 for o3, 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 o3 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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