GPT-5.4 Mini (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, GPT-5.4 Mini holds the stronger ModelCap Index position (#34 vs #53); GPT-5.4 Mini is 1.8× cheaper per output token ($4.50/1M vs $8.00/1M); and GPT-5.4 Mini offers the longer context window (400K vs 200K tokens).
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 Mini vs o3
Public benchmark boards where GPT-5.4 Mini or o3 has a published result
GPT-5.4 Mini ranks higher on the ModelCap Index as of 22 September 2026: #34 against #53. 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-5.4 Mini cheaper than o3?
GPT-5.4 Mini is cheaper on output tokens: $4.50/1M against $8.00/1M. Input tokens are $0.75/1M for GPT-5.4 Mini 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 $3.75 for GPT-5.4 Mini versus $8.00 for o3. GPT-5.4 Mini costs 53.1% 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 Mini or o3?
GPT-5.4 Mini has the larger context window: 400K tokens against 200K.
Which is better for coding, GPT-5.4 Mini or o3?
Arena coding: GPT-5.4 Mini 1496, o3 1460 — GPT-5.4 Mini leads.
Are GPT-5.4 Mini and o3 open-weight models?
GPT-5.4 Mini: API only. 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-5.4 Mini and o3?
ModelCap currently lists 2 API providers for GPT-5.4 Mini 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-5.4 Mini 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.