OpenAI · Released May 5, 2026GPT-5.5 Instant
Compact GPT model for low-latency assistance and high-volume workloads.
- Capability
- 142.5ECI · #89 of 148
- Input
- $5.00per 1M tokens
- Output
- $30.00per 1M tokens
- Context
- 400K128K max output
What it costs
- Input
- $5.00per million tokens
- Output
- $30.00per million tokens
- Blended (3:1)
- $11.25pricier than 94% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $25.00 |
| Team assistant25M input + 5M output tokens | $275.00 |
| Production app250M input + 50M output tokens | $2,750 |
Median of 3 paid API providers on models.dev.
Independent benchmarks
#89 of 148 scored models
The shaded band is Epoch AI’s confidence range (140.0–145.3); the tick marks the median scored model.
Scores from Epoch AI, run independently of OpenAI.
The details
- Lab
- OpenAI
- Released
- May 5, 2026
- Knowledge cutoff
- Dec 1, 2025
- Context window
- 400,000 tokens
- Max output
- 128,000 tokens
- Inputs
- Text, Images, PDFs
- Output
- Text
- Reasoning
- Always on
- Tool calling
- Yes
- Structured output
- Yes
- Weights
- Proprietary
- Availability
- 3 API providerslisted on models.dev
More from OpenAI
About GPT-5.5 Instant
How much does GPT-5.5 Instant cost?
GPT-5.5 Instant costs $5.00 input / $30.00 output per million tokens (median across 3 API providers). At a 3:1 input-to-output mix that is $11.25 per million tokens, more expensive than 94% of the 360 priced models we track.
What is the context window of GPT-5.5 Instant?
GPT-5.5 Instant accepts up to 400,000 tokens per request and can write up to 128,000 tokens in one response.
How good is GPT-5.5 Instant?
Epoch AI gives GPT-5.5 Instant a Capabilities Index score of 142.5 (likely range 140.0–145.3), ranking it #89 of 148 models Epoch has scored. Epoch AI benchmark results: GPQA Diamond 82.5%, FrontierMath Tiers 1–3 26.3%, OTIS Mock AIME 2024–2025 68.1%.
Is GPT-5.5 Instant open source?
No. GPT-5.5 Instant is proprietary; you use it through an API or partner platforms.
What inputs does GPT-5.5 Instant support?
GPT-5.5 Instant accepts text, images and PDFs and replies in text. It is a reasoning model, supports tool calling and can return structured JSON output.
When was GPT-5.5 Instant released?
OpenAI released GPT-5.5 Instant on May 5, 2026. Its training data runs to Dec 1, 2025.
What are the best alternatives to GPT-5.5 Instant?
The closest current models from other labs on capability, price and release date are Mistral Medium 3.5 (Mistral AI, ECI 141.4, $1.50 / $7.50), Claude Sonnet 4 (Anthropic, ECI 141.7, $3.00 / $15.00), Inkling (Thinking Machines, ECI 148.6, $3.74 / $9.36) and Qwen3 Max (Alibaba (Qwen), ECI 142.4, $1.20 / $6.00).