GPT-5.5 — Specifications
| Developer | OpenAI |
|---|---|
| Type | LLM (reasoning) |
| Modality | Text, Vision → Text |
| Parameters | Undisclosed |
| Context window | 1.05M |
| Max output | 128K |
| License | Proprietary |
| Open weights | No |
| Released | 2026 |
| Input price | $5.00 /1M |
| Output price | $30.00 /1M |
| API providers | OpenAI, Azure |
What is GPT-5.5?
GPT-5.5 is OpenAI’s flagship, covering frontier reasoning across coding, writing, research
and multimodal tasks with a context window of roughly 1.05M tokens. Pricing is $5 in / $30
out per million tokens, and a GPT-5.5 Pro tier exists for the highest-stakes reasoning.
Two pricing details shape how it should be used. First, prompts above 272K input tokens
are billed at a higher rate, so the effective cost of a long-context feature is not the
headline number — budget the premium explicitly or keep prompts under the threshold with
tighter retrieval. Second, the 6× output-to-input ratio is one of the steepest in the
frontier bracket: at $30 per million output tokens, generation-heavy workloads such as long
report writing or verbose agent traces cost far more than prompt-heavy ones like retrieval
and classification. Teams that instrument their token mix usually find output is where the
bill actually lives, and that trimming verbosity, capping max_tokens and moving first drafts
to a cheaper model saves more than any prompt-compression trick. Compare it directly against
Claude Opus 4.8, which charges $25 output with no long-context premium.
GPT-5.5 pricing: API cost per 1M tokens
| Input (per 1M tokens) | $5.00 |
|---|---|
| Output (per 1M tokens) | $30.00 |
| Output/input ratio | 6× |
| Blended (4:1 in:out) | $10.00 per 1M tokens |
What GPT-5.5 costs per month
Real monthly spend at a 4:1 input-to-output mix — the ratio a typical chat or RAG workload actually produces.
| Workload | Tokens / month | Cost / month |
|---|---|---|
| Side project | 1M in / 0.25M out | $13 |
| Small team | 20M in / 5M out | $250 |
| Production | 200M in / 50M out | $2,500 |
Run your own numbers in the AI API cost calculator.
Cheaper alternatives to GPT-5.5
| Model | Blended $/1M | You save |
|---|---|---|
| Claude Opus 5 | $9.00 | 10% cheaper |
| Kimi K3 open | $5.40 | 46% cheaper |
| Claude Opus 4.8 | $9.00 | 10% cheaper |
Frequently asked questions
How much does GPT-5.5 cost per 1M tokens?
GPT-5.5 costs $5.00 per 1M input tokens and $30.00 per 1M output tokens. At a typical 4:1 input-to-output mix that blends to about $10.00 per 1M tokens.
How much does GPT-5.5 cost per month?
A small-team workload of 20M input and 5M output tokens a month costs about $250 on GPT-5.5. A side project (1M in / 0.25M out) costs roughly $12.50.
What is a cheaper alternative to GPT-5.5?
Claude Opus 5 is the strongest cheaper option in our database at $9.00 per 1M blended — about 10% less than GPT-5.5.
Can I run GPT-5.5 locally?
No. GPT-5.5 is a closed, API-only model — the weights are not released, so it cannot be self-hosted.
Why does GPT-5.5 charge more for output than input?
Output tokens are generated one at a time and cannot be batched the way a prompt can, so they cost the provider more to serve. GPT-5.5 charges 6× more for output, which is why prompt-heavy workloads are far cheaper to run than generation-heavy ones.
Prices are the published list rates for the model's primary API and are reviewed as providers change them. Volume, batch and cached-input discounts are not included. Compare every model side by side in the AI models database or the LLM leaderboard.
