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-5.2, 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%). The full SWE-bench Verified leaderboard ranks every current model.
- →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 (successor: GLM-5.2) | MIT | 44B (745B total) | 77.8% SWE-Bench, smaller hardware footprint |
| Kimi K2.6 (successor: Kimi K3) | 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-5.6 — OpenAI's next release, split into Luna, Terra and Sol tiers
- → Best Claude model for coding — Sonnet 4.6 is the best-value frontier-class pick: $3/$15, 1M context
- → Gemini 3.1 Pro — 1M context + thinking tiers
- → DeepSeek V4 — open-weight frontier alternative
- → Kimi K3 — Moonshot's successor to Kimi K2.6, the open-weight 1T MoE that tied GPT-5.5 on coding
- → AI model leaderboard: local and frontier models ranked
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Written by
Barsha Mohapatra
Founder and Editor, Local AI Master · Founder, Little AI Master
Founder of Little AI Master and the editor behind every course and guide on Local AI Master. Years of tutoring students taught her where AI education actually fails.