Model comparison
GPT-5.3-Codex vs GPT-5.4 Nano
Two OpenAI tiers compared on the figures that decide which one a workload actually needs.
Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below
OpenAI
GPT-5.3-Codex
Frontier
OpenAI
GPT-5.4 Nano
Budget
| Specification | GPT-5.3-Codex | GPT-5.4 Nano |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Tier | Frontier | Budget |
| Context window | 400K | 400K |
| Max output | 128K | 128K |
| Input / 1M tokens | $1.75 | Winner: $0.20 |
| Output / 1M tokens | $14 | Winner: $1.25 |
| Weights | Closed | Closed |
| Parameters | Not disclosedUnverified | Not disclosedUnverified |
| Reasoning levels | none, low, medium, high, xhigh, max | none, low, medium, high |
| Modalities | text, image | text, image |
| API model id | gpt-5.3-codex | gpt-5.4-nano |
| Released | February 5, 2026 | March 17, 2026 |
| Artificial Analysis Intelligence Index [high] (2026-08-14) | Winner: 52 | 40 |
Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.
Benchmark receipts
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
Pricing tiers: GPT-5.3-Codex: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. · GPT-5.4 Nano: Standard $0.20/$1.25 per MTok; cached input $0.02/MTok; batch $0.10/$0.625.
GPT-5.3-Codex
GPT-5.3-Codex is OpenAI's coding-specialised model powering the Codex agent at $1.75/$14.
Best for
- Autonomous coding
- Repo-scale refactors
- Test generation
Watch out
Tuned for coding, not general chat; use GPT-5.6 for broad reasoning.
GPT-5.4 Nano
GPT-5.4 Nano is OpenAI's cheapest small tier for classification and extraction at $0.20/$1.25.
Best for
- Classification
- Summarisation
- High-volume chat
Watch out
Smallest tier; not for hard reasoning or coding.
When the cheaper one wins
GPT-5.4 Nano is cheaper on output at $1.25 per million tokens against $14 for GPT-5.3-Codex — about 11×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.
Run the model pickerEvidence confidence: High
How strong and complete the evidence behind this comparison is — not a prediction of which model is better.
- Pricing verified on both sides — Input and output rates are verified for both models.
- 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
- 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
- Verified within the last 90 days — Newest catalog check was 8 days ago.
- Both models carry source citations — Each side has at least two catalog sources on record.
Source receipts
Each catalog figure was checked against the provider or an independent second source on the date shown.
- GPT-5.3-Codex: OpenAI — Introducing GPT-5.3-Codex (accessed 2026-08-29)
- GPT-5.3-Codex: OpenAI API pricing (gpt-5.3-codex $1.75/$14) (accessed 2026-08-29)
- GPT-5.4 Nano: OpenAI — GPT-5.4 Mini & Nano (accessed 2026-08-29)
- GPT-5.4 Nano: OpenAI API pricing (gpt-5.4-nano $0.20/$1.25) (accessed 2026-08-29)
Related comparisons
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- Claude Haiku 4.5 vs GPT-5.4 Nano
- Claude Mythos 5.1 vs GPT-5.3-Codex
- Claude Opus 5 vs GPT-5.3-Codex
- DeepSeek V3.1 vs GPT-5.4 Nano
Diving deeper on one model? GPT-5.3-Codex · GPT-5.4 Nano
Common questions
GPT-5.3-Codex vs GPT-5.4 Nano
Answered from the verified figures on this page rather than general guidance.
Is GPT-5.3-Codex or GPT-5.4 Nano cheaper for input?
GPT-5.4 Nano is cheaper at $0.20 per million input tokens, against $1.75 for GPT-5.3-Codex — roughly 8.8× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.3-Codex has tiered pricing: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. GPT-5.4 Nano has tiered pricing: Standard $0.20/$1.25 per MTok; cached input $0.02/MTok; batch $0.10/$0.625.
Is GPT-5.3-Codex or GPT-5.4 Nano cheaper for output?
GPT-5.4 Nano is cheaper at $1.25 per million output tokens, against $14 for GPT-5.3-Codex — roughly 11× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.3-Codex has tiered pricing: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. GPT-5.4 Nano has tiered pricing: Standard $0.20/$1.25 per MTok; cached input $0.02/MTok; batch $0.10/$0.625.
Which has the larger context window, GPT-5.3-Codex or GPT-5.4 Nano?
Both accept about 400K tokens of context, so document length will not decide between them.
Do GPT-5.3-Codex and GPT-5.4 Nano support the same reasoning levels?
GPT-5.3-Codex exposes none, low, medium, high, xhigh, max, while GPT-5.4 Nano exposes none, low, medium, high.
Should I use GPT-5.3-Codex or GPT-5.4 Nano?
GPT-5.3-Codex is the frontier tier and GPT-5.4 Nano the budget tier. The useful question is whether your hardest task actually fails on the cheaper one — most production volume such as classification, extraction and summarisation does not.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: GPT-5.4 Nano costs $0.20 per 1M tokens versus $1.75 for GPT-5.3-Codex — a 8.8x difference at the headline tier.
- Measured capability: GPT-5.3-Codex leads Artificial Analysis Intelligence Index 52 to 40 (measured 2026-08-14).
- Positioning: GPT-5.3-Codex sits in the frontier tier, GPT-5.4 Nano in the budget tier — most production volume (classification, extraction, summarisation) does not need the pricier tier.
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.