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Head-to-head comparison

GPT-6 Astra vs gpt-oss-20b

GPT-6 Astra (OpenAI) and gpt-oss-20b (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 9 September 2026

As of 9 September 2026, GPT-6 Astra holds the stronger ModelCap Index position (#1 vs #135); gpt-oss-20b is 384.6× cheaper per output token ($0.13/1M vs $50.00/1M); GPT-6 Astra offers the longer context window (1M vs 131K tokens); and gpt-oss-20b ships open weights.

Which should you choose?

Choose GPT-6 Astra if…

  • you want the stronger overall ModelCap Index position — #1 against #135 (93.7 vs 27.9 points).
  • you need the longer context window — 1M tokens against 131K.
  • AA Intelligence Index is your yardstick — 52.8 against 9.0.
  • AA Terminal-Bench 2.1 is your yardstick — 88.4% against 13.9%.
  • AA Humanity's Last Exam is your yardstick — 54.7% against 11.0%.
  • you want the more recently listed model — GPT-6 Astra was listed 4 September 2026, gpt-oss-20b 5 August 2025.

Choose gpt-oss-20b if…

  • API cost matters — $0.13/1M output tokens against $50.00/1M, about 384.6× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.03/1M against $10.00/1M.
  • you want to self-host: gpt-oss-20b ships open weights while GPT-6 Astra is api only.
  • you want provider choice — 12 listed API providers against 2.

GPT-6 Astra vs gpt-oss-20b: specs, pricing and context

Specification comparison of GPT-6 Astra and gpt-oss-20b
FieldGPT-6 AstraOpenAIgpt-oss-20bOpenAI
ModelCap Index position#1#135
Index score93.727.9
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$0.03
Output price / 1M tokens$50.00$0.13
Context window1M tokens131K tokens
Max output tokens128K118K
API providers listed212
Weight accessAPI onlyOpen weights
Input modalitiesFile, Image, TextText
First listed4 September 20265 August 2025
PublisherOpenAIOpenAI

Evidence: 4 public benchmark observations across 4 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-6 Astra vs gpt-oss-20b

Public benchmark boards where GPT-6 Astra or gpt-oss-20b has a published result
BoardGPT-6 Astragpt-oss-20bLeads
Arena codingArena (LMArena)—13691356–1382Only one result
LMArena AgentLMArena12.5%10.4%–14.7%Max—Only one result
ARC-AGI-2ARC Prize Foundation95.0%Max—Only one result
ARC-AGI-3ARC Prize Foundation62.7%Max—Only one result
AA Intelligence IndexArtificial Analysis52.8intelligence-index:v4.3:max9.0intelligence-index:v4.3:highGPT-6 Astra
AA Terminal-Bench 2.1Artificial Analysis88.4%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GPT-6 Astra (max)":reasoning=true13.9%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="gpt-oss-20b (high)":reasoning=trueGPT-6 Astra
AA τ²-Bench TelecomArtificial Analysis—60.2%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="gpt-oss-20b (high)":reasoning=trueOnly one result
AA Humanity's Last ExamArtificial Analysis54.7%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-6 Astra (max)":reasoning=true11.0%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="gpt-oss-20b (high)":reasoning=trueGPT-6 Astra
Terminal-Bench 4.0Terminal-Bench (Laude Institute)58.2%55.4%–61.0%Codex · Max—Only one result

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-6 Astra vs gpt-oss-20b: common questions

Is GPT-6 Astra better than gpt-oss-20b?

GPT-6 Astra ranks higher on the ModelCap Index as of 9 September 2026: #1 against #135. 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-6 Astra cheaper than gpt-oss-20b?

gpt-oss-20b is cheaper on output tokens: $0.13/1M against $50.00/1M. Input tokens are $10.00/1M for GPT-6 Astra and $0.03/1M for gpt-oss-20b. 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 $45.00 for GPT-6 Astra versus $0.13 for gpt-oss-20b. gpt-oss-20b costs 99.7% 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-6 Astra or gpt-oss-20b?

GPT-6 Astra has the larger context window: 1M tokens against 131K.

Which is better for coding, GPT-6 Astra or gpt-oss-20b?

AA Terminal-Bench 2.1: GPT-6 Astra 88.4%, gpt-oss-20b 13.9% — GPT-6 Astra leads.

Are GPT-6 Astra and gpt-oss-20b open-weight models?

GPT-6 Astra: API only. gpt-oss-20b: Open weights. 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-6 Astra and gpt-oss-20b?

ModelCap currently lists 2 API providers for GPT-6 Astra and 12 for gpt-oss-20b, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this GPT-6 Astra vs gpt-oss-20b comparison?

Every figure comes from the sealed ModelCap dataset published 9 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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