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Head-to-head comparison

GPT-5.4 Nano vs gpt-oss-20b

GPT-5.4 Nano (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 22 September 2026

As of 22 September 2026, GPT-5.4 Nano holds the stronger ModelCap Index position (#81 vs #162); gpt-oss-20b is 13.9× cheaper per output token ($0.09/1M vs $1.25/1M); GPT-5.4 Nano offers the longer context window (400K vs 131K tokens); and gpt-oss-20b ships open weights.

Which should you choose?

Choose GPT-5.4 Nano if…

  • you want the stronger overall ModelCap Index position — #81 against #162 (57.3 vs 35.3 points).
  • you need the longer context window — 400K tokens against 131K.
  • Arena coding is your yardstick — 1460 against 1369.
  • AA Intelligence Index is your yardstick — 20.7 against 9.0.
  • AA τ²-Bench Telecom is your yardstick — 76.0% against 60.2%.
  • AA Humanity's Last Exam is your yardstick — 28.3% against 11.0%.
  • you want the more recently listed model — GPT-5.4 Nano was listed 17 March 2026, gpt-oss-20b 5 August 2025.

Choose gpt-oss-20b if…

  • API cost matters — $0.09/1M output tokens against $1.25/1M, about 13.9× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.018/1M against $0.20/1M.
  • you want to self-host: gpt-oss-20b ships open weights while GPT-5.4 Nano is api only.
  • you want provider choice — 11 listed API providers against 2.

GPT-5.4 Nano vs gpt-oss-20b: specs, pricing and context

Specification comparison of GPT-5.4 Nano and gpt-oss-20b
FieldGPT-5.4 NanoOpenAIgpt-oss-20bOpenAI
ModelCap Index position#81#162
Index score57.335.3
EvidenceMeasuredMeasured
Input price / 1M tokens$0.20$0.018
Output price / 1M tokens$1.25$0.09
Context window400K tokens131K tokens
Max output tokens128K33K
API providers listed211
Weight accessAPI onlyOpen weights
Input modalitiesFile, Image, TextText
First listed17 March 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-5.4 Nano vs gpt-oss-20b

Public benchmark boards where GPT-5.4 Nano or gpt-oss-20b has a published result
BoardGPT-5.4 Nanogpt-oss-20bLeads
Arena codingArena (LMArena)14601454–1466High13691356–1382GPT-5.4 Nano
ARC-AGI-2ARC Prize Foundation5.7%X-High—Only one result
AA Intelligence IndexArtificial Analysis20.7intelligence-index:v4.3:xhigh9.0intelligence-index:v4.3:highGPT-5.4 Nano
AA τ²-Bench TelecomArtificial Analysis76.0%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="GPT-5.4 nano (xhigh)":reasoning=true60.2%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="gpt-oss-20b (high)":reasoning=trueGPT-5.4 Nano
AA Humanity's Last ExamArtificial Analysis28.3%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-5.4 nano (xhigh)":reasoning=true11.0%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="gpt-oss-20b (high)":reasoning=trueGPT-5.4 Nano

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-5.4 Nano vs gpt-oss-20b: common questions

Is GPT-5.4 Nano better than gpt-oss-20b?

GPT-5.4 Nano ranks higher on the ModelCap Index as of 22 September 2026: #81 against #162. 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-5.4 Nano cheaper than gpt-oss-20b?

gpt-oss-20b is cheaper on output tokens: $0.09/1M against $1.25/1M. Input tokens are $0.20/1M for GPT-5.4 Nano and $0.018/1M 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 $1.02 for GPT-5.4 Nano versus $0.08 for gpt-oss-20b. gpt-oss-20b costs 92.1% 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-5.4 Nano or gpt-oss-20b?

GPT-5.4 Nano has the larger context window: 400K tokens against 131K.

Which is better for coding, GPT-5.4 Nano or gpt-oss-20b?

Arena coding: GPT-5.4 Nano 1460, gpt-oss-20b 1369 — GPT-5.4 Nano leads.

Are GPT-5.4 Nano and gpt-oss-20b open-weight models?

GPT-5.4 Nano: 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-5.4 Nano and gpt-oss-20b?

ModelCap currently lists 2 API providers for GPT-5.4 Nano and 11 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-5.4 Nano vs gpt-oss-20b 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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