Model Details
GPT-5.1 Instant
Quick answer: GPT-5.1 Instant is OpenAI's fast, low-cost model in the GPT-5.1 family — analogous to Claude Haiku in the Anthropic line. Designed for real-time applications, high-volume pipelines, and sub-agent workloads where latency and cost are primary constraints rather than maximum reasoning depth.
What GPT-5.1 Instant Is
GPT-5.1 Instant occupies the speed/cost tier of OpenAI's model family, sitting below GPT-5.1 in capability but well above the previous GPT-3.5 and GPT-4o Mini class. As frontier model capability has cascaded down to the efficient tier (mirroring Haiku 4.5 matching Sonnet 4 on SWE-bench at one-fifth the cost), Instant models have become the default for most production traffic.
For agent architectures, GPT-5.1 Instant is well-suited as a sub-agent or tool router in a multi-agent system, with GPT-5.1 or GPT-5.1 Codex handling orchestration and complex reasoning.
Specifications
| Field | Value |
|---|---|
| Organization | OpenAI |
| Tier | Fast / efficient |
| License | Proprietary |
| Modality | Multimodal (text and vision) |
Pricing
| Input (per 1M tokens) | Output (per 1M tokens) | |
|---|---|---|
| OpenAI | $0.15 | $0.60 |
Related Models & Benchmarks
- Compare: GPT-5.1 · GPT-5.1 Thinking · Claude Haiku 4.5
- Benchmarks: SWE-bench Verified
GPT-5.1 Instant vs Alternatives
| Model | BrowseComp | GPQA-Diamond | HLE | License |
|---|---|---|---|---|
| GPT-5.1 Instant | 90.0% | 88.1% | 6.80% | Proprietary |
| GPT-5.1 Thinking | 90.0% | 88.1% | 23.68% | Proprietary |
GPT-5.1 Instant vs Thinking: identical BrowseComp + GPQA-Diamond, lower HLE (6.80% vs 23.68%). Use Instant for cost/speed; Thinking for frontier reasoning.
Frequently Asked Questions
What is GPT-5.1 Instant?
OpenAI's February 2026 fast variant scoring 90.0% BrowseComp, 88.1% GPQA-Diamond, 6.80% HLE. Proprietary.Scores from Benchgen evaluations. Last updated 2026-07-24.
Benchmark Leaderboards
This model isn’t on any benchmark leaderboard yet.