Model comparison
GPT-5.5 vs GPT-5.5 Pro
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-5.5
Frontier
OpenAI
GPT-5.5 Pro
Frontier
| Specification | GPT-5.5 | GPT-5.5 Pro |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Tier | Frontier | Frontier |
| Context window | 1.05M | 1.05M |
| Max output | 128K | 128K |
| Input / 1M tokens | Winner: $5 | $30 |
| Output / 1M tokens | Winner: $30 | $180 |
| Weights | Closed | Closed |
| Parameters | Not disclosedUnverified | Not disclosedUnverified |
| Reasoning levels | none, low, medium, high, xhigh, max | none, low, medium, high, xhigh, max |
| Modalities | text, image | text, image |
| API model id | gpt-5.5 | gpt-5.5-pro |
| Released | April 23, 2026 | April 23, 2026 |
| Artificial Analysis Intelligence Index [xhigh] (2026-08-14) | 58 | Winner: 60 |
| SWE-bench Verified (2026-09-01) | 82.6 | Not verifiedUnverified |
| Terminal-Bench 2.1 (2026-07-27) | 83.4 | Not verifiedUnverified |
| GPQA Diamond (2026-07-27) | 93.5 | Not verifiedUnverified |
| Humanity's Last Exam (2026-04-23) | 52.2 | Not verifiedUnverified |
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
- 2026-09-01: vals.ai SWE-bench Verified leaderboard (independent, mini-swe-agent bash-only); official SWE-bench not publishedReal GitHub issue resolution: does the model's patch pass the hidden tests. Comparability: comparable with caveat — Post-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.
- 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).
- 2026-07-27: Kimi K3 model card (vendor-reported, xhigh); announcement charts show 93.6 — minor conflict preservedAgentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-04-23: OpenAI — Introducing GPT-5.5 (vendor, with tools; 41.4 no tools)Frontier-knowledge ceiling: extremely hard multi-domain questions written to be near-impossible without deep expertise. Comparability: comparable with caveat — Subset/tool configurations (text-only vs with-tools) differ between vendors and materially change scores; must match configuration to compare.
Pricing tiers: GPT-5.5: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. · GPT-5.5 Pro: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
GPT-5.5
GPT-5.5 is OpenAI's previous flagship — strong on Terminal-Bench 2.0 (82.7%) and 1M-token context.
Best for
- Reasoning
- Agentic coding
- Long-context work
Watch out
Superseded by GPT-5.6 Sol on quality; still a capable, widely integrated model.
GPT-5.5 Pro
GPT-5.5 Pro is OpenAI's highest-effort tier for maximal accuracy on the hardest tasks.
Best for
- Maximum-accuracy reasoning
- Research
- Hard enterprise workloads
Watch out
At $30/$180 per MTok it is the most expensive OpenAI tier; reserve for work that needs it.
When the cheaper one wins
GPT-5.5 is cheaper on output at $30 per million tokens against $180 for GPT-5.5 Pro — about 6.0×. 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-5.5: OpenAI — Introducing GPT-5.5 (accessed 2026-08-29)
- GPT-5.5: OpenAI API pricing (gpt-5.5 $5/$30) (accessed 2026-08-29)
- GPT-5.5 Pro: OpenAI — Introducing GPT-5.5 (accessed 2026-08-29)
- GPT-5.5 Pro: OpenAI API pricing (gpt-5.5-pro $30/$180) (accessed 2026-08-29)
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- Claude Mythos 5.1 vs GPT-5.5
- Claude Mythos 5.1 vs GPT-5.5 Pro
Diving deeper on one model? GPT-5.5 · GPT-5.5 Pro
Common questions
GPT-5.5 vs GPT-5.5 Pro
Answered from the verified figures on this page rather than general guidance.
Is GPT-5.5 or GPT-5.5 Pro cheaper for input?
GPT-5.5 is cheaper at $5 per million input tokens, against $30 for GPT-5.5 Pro — roughly 6.0× 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-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. GPT-5.5 Pro has tiered pricing: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
Is GPT-5.5 or GPT-5.5 Pro cheaper for output?
GPT-5.5 is cheaper at $30 per million output tokens, against $180 for GPT-5.5 Pro — roughly 6.0× 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-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. GPT-5.5 Pro has tiered pricing: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
Which has the larger context window, GPT-5.5 or GPT-5.5 Pro?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do GPT-5.5 and GPT-5.5 Pro support the same reasoning levels?
Yes — both accept the same effort settings: "none", "low", "medium", "high", "xhigh", "max". Higher effort costs more and takes longer, so start low and raise it only where output quality actually improves.
Should I use GPT-5.5 or GPT-5.5 Pro?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. GPT-5.5 suits reasoning; GPT-5.5 Pro suits maximum-accuracy reasoning.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: GPT-5.5 costs $5 per 1M tokens versus $30 for GPT-5.5 Pro — a 6x difference at the headline tier.
- Measured capability: GPT-5.5 Pro leads Artificial Analysis Intelligence Index 60 to 58 (measured 2026-08-14).
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.