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Head-to-head comparison

gpt-oss-20b vs o3

gpt-oss-20b (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 #163); gpt-oss-20b is 88.9× cheaper per output token ($0.09/1M vs $8.00/1M); o3 offers the longer context window (200K vs 131K tokens); and gpt-oss-20b ships open weights.

Which should you choose?

Choose gpt-oss-20b if…

  • API cost matters — $0.09/1M output tokens against $8.00/1M, about 88.9× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.018/1M against $2.00/1M.
  • you want to self-host: gpt-oss-20b ships open weights while o3 is api only.
  • you want provider choice — 11 listed API providers against 1.
  • you want the more recently listed model — gpt-oss-20b was listed 5 August 2025, o3 16 April 2025.

Choose o3 if…

  • you want the stronger overall ModelCap Index position — #53 against #163 (66.5 vs 35.3 points).
  • you need the longer context window — 200K tokens against 131K.
  • Arena coding is your yardstick — 1460 against 1369.
  • AA τ²-Bench Telecom is your yardstick — 80.7% against 60.2%.
  • AA Humanity's Last Exam is your yardstick — 20.1% against 11.0%.

gpt-oss-20b vs o3: specs, pricing and context

Specification comparison of gpt-oss-20b and o3
Fieldgpt-oss-20bOpenAIo3OpenAI
ModelCap Index position#163#53
Index score35.366.5
EvidenceMeasuredMeasured
Input price / 1M tokens$0.018$2.00
Output price / 1M tokens$0.09$8.00
Context window131K tokens200K tokens
Max output tokens33K100K
API providers listed111
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-20b vs o3

Public benchmark boards where gpt-oss-20b or o3 has a published result
Boardgpt-oss-20bo3Leads
Arena codingArena (LMArena)13691356–138214601454–1467o3
ARC-AGI-2ARC Prize Foundation—6.5%HighOnly one result
SWE-benchSWE-bench (Princeton / SWE-agent team)—58.4%Only one result
BFCL V4UC Berkeley (Gorilla)—63.1PromptOnly one result
AA Intelligence IndexArtificial Analysis9.0intelligence-index:v4.3:high—Only one result
AA τ²-Bench TelecomArtificial Analysis60.2%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="gpt-oss-20b (high)":reasoning=true80.7%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="o3":reasoning=trueo3
AA Humanity's Last ExamArtificial Analysis11.0%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="gpt-oss-20b (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-20b vs o3: common questions

Is gpt-oss-20b better than o3?

o3 ranks higher on the ModelCap Index as of 22 September 2026: #53 against #163. 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-20b cheaper than o3?

gpt-oss-20b is cheaper on output tokens: $0.09/1M against $8.00/1M. Input tokens are $0.018/1M for gpt-oss-20b 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 $0.08 for gpt-oss-20b versus $8.00 for o3. gpt-oss-20b costs 99.0% 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-20b or o3?

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

Which is better for coding, gpt-oss-20b or o3?

Arena coding: gpt-oss-20b 1369, o3 1460 — o3 leads.

Are gpt-oss-20b and o3 open-weight models?

gpt-oss-20b: 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-20b and o3?

ModelCap currently lists 11 API providers for gpt-oss-20b 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-20b 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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