OpenAI · Closed-API Model
GPT-5.5 Review: ChatGPT's New Default, Tested
OpenAI shipped GPT-5.5 between April 23 and May 5, 2026 across three tiers — Instant, Standard, and Pro — and made it the default model for all ChatGPT users. This review covers what changed from GPT-5, real benchmark performance (95.2% AIME math, 85.1% SWE-Bench), the new 1M context window, pricing across all three tiers, and which open-weight alternatives come closest if you need to self-host.
Note: GPT-5.5 is API-only — it cannot be downloaded or run locally. For self-hostable models with comparable performance, see DeepSeek V4, GLM-5, and Qwen3-Coder-Next.
Key takeaways
- →3 tiers: Instant ($1.50/$6), Standard ($5/$30), Pro ($30/$180) per million tokens.
- →1M context — 8× GPT-5's 128K, on par with Gemini 3.1 Pro.
- →95.2% AIME 2025 — top math benchmark, beats Sonnet 4.6 (91.5%) and Gemini 3.1 (94.0%).
- →85.1% SWE-Bench Verified — strong coding, behind the SWE-Bench frontier (Gemini 3.1 Pro 87.9%; Claude Sonnet 4.6 79.6%).
- →API-only — for self-hosting, DeepSeek V4-Pro is the closest frontier open-weight match.
Quick verdict
GPT-5.5 is the default ChatGPT model and the best general-purpose closed model for math-heavy and ChatGPT-ecosystem workloads. If you live in ChatGPT, use custom GPTs, or rely on OpenAI's function-calling and tools APIs, this is the model you should use.
Where it loses: pricing ($5/$30 is the most expensive of the three frontier closed models — Claude Sonnet 4.6 delivers near-flagship quality at $3/$15, about 1/8 the cost, with a 1M context window — and GPT-5.5 Pro at $30/$180 is pricier still). For local-first deployment, DeepSeek V4-Pro gets you most of GPT-5.5's capabilities at zero per-token cost.
Specs at a glance
| Vendor | OpenAI |
| Release date | April 23, 2026 (standard) · May 5, 2026 (Instant) |
| Tiers | Instant · Standard · Pro |
| Context window | 1,000,000 tokens |
| Max output | 32,000 tokens |
| Modalities | Text · Code · Image · Audio (via Realtime API) |
| License | Proprietary (OpenAI Terms of Service) |
| Local self-hostable? | No |
| API model IDs | gpt-5.5 · gpt-5.5-instant · gpt-5.5-pro |
| Knowledge cutoff | March 2026 |
Three tiers explained
GPT-5.5 ships in three tiers. Picking the right one for each request controls cost and latency.
GPT-5.5 Instant — $1.50 / $6 per Mtok
Sub-200ms latency. Smaller activated parameters, same knowledge cutoff. Use for chat, autocomplete, classification, simple Q&A. Quality ~80-85% of Standard.
GPT-5.5 Standard — $5 / $30 per Mtok
The default ChatGPT model. Best balance of speed (~1-3 sec first token) and quality. Use for coding, content, analysis, function calling. Most production work belongs here.
GPT-5.5 Pro (Extended Thinking) — $30 / $180 per Mtok
Extended reasoning over 30 seconds to several minutes. Use for hardest math, novel algorithms, ambiguous specs, research-grade analysis. Available via ChatGPT Pro ($200/mo) and API at higher rate limits.
Benchmarks vs the competition
| Benchmark | GPT-5.5 | GPT-5 | Claude Sonnet 4.6 | Gemini 3.1 Pro |
|---|---|---|---|---|
| AIME 2025 (math) | 95.2% | 87.4% | 91.5% | 94.0% |
| MMLU-Pro (knowledge) | 90.1% | 86.2% | 87.9% | 89.4% |
| SWE-Bench Verified | 85.1% | 74.9% | 79.6% | 87.9% |
| ARC-AGI-2 (reasoning) | 71.3% | 58.4% | 68.4% | 77.1% |
| GPQA Diamond | 86.0% | 83.1% | 85.7% | 88.2% |
| HumanEval | 94.2% | 92.6% | 95.8% | 93.7% |
Sources: OpenAI GPT-5.5 release notes (April-May 2026), Anthropic Sonnet 4.6 announcement, Google Gemini 3.1 Pro model card, Artificial Analysis leaderboard. · OpenAI release notes
Pricing & access
API pricing
- Instant: $1.50 / $6.00 per 1M tokens
- Standard: $5.00 / $30.00 per 1M tokens
- Pro: $30.00 / $180.00 per 1M tokens
- Cached input: 50% off
- Batch API: 50% off (24h SLA)
Subscription tiers
- ChatGPT Free: Limited GPT-5.5 Instant
- ChatGPT Plus: $20/mo — Standard with daily caps
- ChatGPT Pro: $200/mo — unlimited Standard + Pro
- Team: $30/user/mo — collaboration
- Enterprise: Custom — SSO, audit, custom limits
Heavy GPT-5.5 API users typically pay $50-400/month. For comparison, a self-hosted DeepSeek V4 on a $10-15K multi-GPU rig pays for itself in 2-3 years and gives you unlimited inference + full data privacy.
When to pick GPT-5.5 vs alternatives
| Workload | Best pick | Why |
|---|---|---|
| Math / scientific computation | GPT-5.5 Pro | 95.2% AIME 2025; extended thinking handles hardest problems. |
| Best-value coding | Claude Sonnet 4.6 | 79.6% SWE-Bench at $3/$15 (~1/8 GPT-5.5's cost) + 1M context. |
| Whole-codebase analysis | Gemini 3.1 Pro | Both 1M context; Gemini is cheaper per token at long context. |
| ChatGPT ecosystem (custom GPTs, plugins) | GPT-5.5 Standard | Native integration; nothing else comes close. |
| High-volume routine tasks | GPT-5.5 Instant | $1.50/$6 per Mtok at 80-85% of Standard quality. |
| Privacy-required workloads | DeepSeek V4 | Self-hostable, MIT licensed, 1M context. |
Open-weight alternatives
GPT-5.5 is API-only. If you need a frontier-class model that you can self-host — for privacy, cost, or offline operation — these come closest:
| Model | License | Active params | Strength |
|---|---|---|---|
| DeepSeek V4-Pro | MIT | 49B (1.6T total) | Closest general-purpose match |
| GLM-5 | MIT | 44B (745B total) | 77.8% SWE-Bench, smaller hardware footprint |
| Kimi K2.6 | Modified MIT | 32B (1T total) | Ties GPT-5.5 on coding |
| Mistral Medium 3.5 | Modified MIT | 128B dense | Runs on 4 GPUs, near-frontier |
When to pick GPT-5.5
- ✓You live in ChatGPT, use custom GPTs, or rely on OpenAI plugins/function-calling.
- ✓Math-heavy workloads (95.2% AIME is the highest production score).
- ✓You need three tiers (Instant / Standard / Pro) for cost-sensitive routing.
- ✓You're on Azure and need first-class OpenAI integration.
When to pick something else
- →Best-value frontier coding → Claude Sonnet 4.6 (79.6% SWE-Bench at $3/$15, ~1/8 GPT-5.5's price, 1M context).
- →Cheapest long-context analysis → Gemini 3.1 Pro (1M context like GPT-5.5, lower per-token cost).
- →Privacy-required → DeepSeek V4 or other self-hosted open weight.
- →Predictable monthly costs → any local-first deployment.
Frequently asked questions
Can I run GPT-5.5 locally?
How much does GPT-5.5 cost?
GPT-5.5 vs GPT-5: what changed?
GPT-5.5 vs Claude Sonnet 4.6 vs Gemini 3.1 Pro: which is best?
What is GPT-5.5 Pro and when should I use it?
What is GPT-5.5 Instant?
How big is GPT-5.5's context window?
When should I use an open-weight model instead of GPT-5.5?
Cut your GPT-5.5 API bill 60-85%
The Local AI Master deployment course shows you how to run open-weight alternatives like DeepSeek V4 and Qwen3-Coder-Next on your own hardware. Use them for the routine 80% of traffic, keep GPT-5.5 for the hard 20%.
See the deployment course →Related models
- → GPT-5 — predecessor; still available, cheaper at $4/$16
- → Claude Sonnet 4.6 — best-value frontier-class model: $3/$15, 1M context
- → Gemini 3.1 Pro — 1M context + thinking tiers
- → DeepSeek V4 — open-weight frontier alternative
- → Kimi K2.6 — open-weight 1T MoE that ties GPT-5.5 on coding
- → Grok 4.3 — xAI's frontier model at $1.25/$2.50, undercutting GPT-5.5's $5/$30
- → Claude Fable 5 & Mythos 5 — Anthropic's Mythos-class tier, suspended worldwide by export order: why a cloud model can vanish overnight
- → Best AI models May 2026: complete comparison
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