What is GPT 5.5?
GPT 5.5 is OpenAI’s proprietary model for complex professional work, coding, analysis and agents that need adjustable reasoning depth.
QUICK VERDICT: Choose GPT 5.5 when you need complex professional work, coding, analysis and agents that need adjustable reasoning depth. The main trade-off is that It costs more than GPT 5.6 Sol’s documented promotional pricing and long prompts above 272,000 tokens are billed at higher multipliers.
Field | Verified value |
|---|---|
Provider | OpenAI |
Release date | April 24, 2026 (API) |
Availability | Available |
License | Proprietary |
Context window | 1.05M tokens |
Maximum output | 128K tokens |
Modalities | Text and image input; text output |
API pricing | $5 input / $30 output per million tokens |
Best fit | Professional work, coding, analysis and adjustable reasoning |
Last verified | September 2, 2026 |
GPT 5.5 capabilities and architecture
GPT 5.5 supports reasoning effort from none through xhigh, so latency, cost and output quality vary with configuration.
The model accepts text and images and outputs text. Audio and video are not supported on the model page.
Its documented knowledge cutoff is December 1, 2025. Tool calls and regional processing can add separate charges.
The practical lesson is to evaluate the complete system: model, reasoning level, tool permissions, context strategy, agent harness and verification loop. A strong base model can underperform with weak tools or poor task decomposition. Conversely, an effective harness can make a slightly lower-ranked model the better product choice.
Best use cases for GPT 5.5
- Primary fit: complex professional work, coding, analysis and agents that need adjustable reasoning depth.
- Use it for bounded workflows with explicit success criteria, tool permissions and a review step.
- Run a small representative evaluation before migrating a production workload or committing to a large inference budget.
- Keep the exact model snapshot fixed during testing so silent alias changes do not invalidate the comparison.
Access, pricing and deployment
OpenAI API with aliases and lockable snapshots. The current pricing reference is: $5 per million input tokens, $0.50 cached input and $30 per million output tokens. Pricing changes quickly and often depends on caching, batch processing, long-context multipliers, regions and tool calls. Verify the official page before budgeting.
1,050,000-token context window and up to 128,000 output tokens. Context-window size is a capacity ceiling, not evidence that every token will receive equal attention. For long documents or repositories, measure retrieval accuracy, instruction retention, latency and cost at the actual lengths you expect to use.
Limitations and safety
It costs more than GPT 5.6 Sol’s documented promotional pricing and long prompts above 272,000 tokens are billed at higher multipliers.
Do not rely on benchmark claims alone for high-stakes medical, legal, financial, cybersecurity or safety decisions. Require domain review, log model and prompt versions, test failure cases, minimize tool permissions and keep a rollback path. Open weights provide deployment control, but they also move security, patching and abuse prevention responsibilities to the operator.
How to evaluate GPT 5.5 yourself
Test | What to record |
|---|---|
Task completion | Binary success plus a written quality rubric |
Reliability | Pass rate over repeated runs, not one best attempt |
Tool use | Wrong calls, retries, permission requests and recovery |
Quality | Factuality, instruction adherence, citations and deliverable usefulness |
Efficiency | Wall time, input, output, cached tokens and tool fees |
Safety | Unsafe actions, sensitive-data handling and approval-boundary failures |
Use 20 to 50 tasks drawn from your real workload, freeze them before testing, and run every candidate with equivalent tools and budgets. Keep a hidden holdout set so prompts are not gradually optimized for the public examples. Report medians and failure rates, not only impressive demonstrations.
Frequently asked questions
Is GPT 5.5 the best AI model?
That makes it a strong current candidate, but “best” depends on the task, cost, latency, modalities, deployment constraints and the agent harness.
Is GPT 5.5 open source?
No. GPT 5.5 is proprietary and accessed through OpenAI or approved partners.
What is GPT 5.5 best used for?
Its strongest fit is complex professional work, coding, analysis and agents that need adjustable reasoning depth. Start with a supervised pilot and compare it with at least one neighboring model using the same task set.
Can I compare the score directly with vendor benchmarks?
Not safely. Vendor benchmarks may use different prompts, reasoning budgets, tools, sampling, dates and scoring rules. Compare only results produced under the same evaluation protocol.
Official source and update policy
The primary product reference for this guide isOpenAI’s official GPT 5.5 documentation.
We update this guide when the official model specification, access, pricing, material benchmark documentation changes. Checked August 26, 2026. No vendor payment or affiliate relationship determined the ranking.