Current documented limits
| Constraint | Current value | Scope | Verified source |
|---|---|---|---|
| API rate-limit scopeOpenAI measures RPM, RPD, TPM, TPD, IPM, and certain audio limits; the first exhausted limiter applies. | Varies by model and usage tier | All API organizations | OpenAIAug 22, 2026 |
| GPT-5.6 Sol / Terra / Luna context windowModel-specific API context window; output is also bounded separately. | 1,050,000 tokens | GPT-5.6 | OpenAIAug 22, 2026 |
| GPT-5.6 maximum outputSeparate output ceiling shown for the current GPT-5.6 Sol, Terra, and Luna models. | 128,000 tokens | GPT-5.6 | OpenAIAug 22, 2026 |
How to apply OpenAI API limits safely
The monitored baseline covers API rate-limit scope, GPT-5.6 Sol / Terra / Luna context window, GPT-5.6 maximum output. Treat these as separate constraints rather than one platform-wide capacity number: a workload can fit one row and still fail another because the plan, model, endpoint, runtime, region, invocation mode, or account scope differs.
- Match the production workload to the exact scope printed beside each value and confirm it in the active OpenAI API console, configuration, or response headers.
- Measure the serialized request, token volume, duration, concurrency, storage, or connection demand at realistic percentiles, then preserve headroom for bursts and retries.
- Check every adjacent layer—client, SDK, gateway, proxy, queue, database, and downstream service—for a smaller effective limit before changing architecture.
Specific limit pages
These pages exist because the constraint has a distinct implementation or troubleshooting intent. Closely related keyword variations stay consolidated.
OpenAI API rate limits
How OpenAI API rate limits work across models, usage tiers, projects, and response headers, with the current official source.
OpenAI API context windows
Current source-backed GPT-5.6 context-window and maximum-output values, plus the budgeting distinction developers need.
Errors linked to these limits
context_length_exceeded
OpenAI Context Length Exceeded Error: direct meaning, scoped diagnosis, corrective action, official source, and linked current limit.
insufficient_quota
OpenAI Insufficient Quota Error: direct meaning, scoped diagnosis, corrective action, official source, and linked current limit.
429 — Rate limit reached for requests
Diagnose OpenAI API 429 rate-limit responses, distinguish temporary throughput limits from billing/usage errors, and retry safely.
Compare alternatives
Gemini API vs OpenAI API Limits
Gemini API vs OpenAI API Limits using the same verified structured observations as each underlying limit page, with scope and comparability caveats.
OpenAI API vs Anthropic API
Compare current context-window and rate-limit models while preserving model, tier, project, and organization caveats.