LLM Reference

GPT-5.5 vs o3 Deep Research

GPT-5.5 (2026) and o3 Deep Research (2025) are frontier-tier reasoning models from OpenAI. GPT-5.5 ships a 1.05m-token context window, while o3 Deep Research ships a 200k-token context window. On pricing, GPT-5.5 ranges from $5 to $8/1M input tokens by tier; o3 Deep Research costs $10/1M input tokens. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

GPT-5.5 fits 5x more tokens; pick it for long-context work and o3 Deep Research for tighter calls.

Decision scorecard

Local evidence first
SignalGPT-5.5o3 Deep Research
Best forreasoning-heavy apps, multimodal apps, and tool-calling agentsreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsRAG, Agents, and Long context
Context window1.05m200k
Cheapest output$30/1M tokens$40/1M tokens
Provider routes4 tracked1 tracked
Shared benchmarks0 shared0 shared

Decision tradeoffs

Choose GPT-5.5 when...
  • GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • GPT-5.5 has the lower cheapest tracked output price at $30/1M tokens.
  • GPT-5.5 has broader tracked provider coverage for fallback and route flexibility.
  • GPT-5.5 uniquely exposes Code execution in local model data.
  • Local decision data tags GPT-5.5 for Coding, RAG, and Agents.
Choose o3 Deep Research when...
  • Local decision data tags o3 Deep Research for RAG, Agents, and Long context.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate GPT-5.5

GPT-5.5

$11,500

Cheapest tracked route/tier: OpenAI API 0-272K input tokens

o3 Deep Research

$18,000

Cheapest tracked route/tier: Vercel AI Gateway

Estimated monthly gap: $6,500. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

GPT-5.5 -> o3 Deep Research
  • Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
  • o3 Deep Research is $10/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Check replacement coverage for Code execution before moving production traffic.
o3 Deep Research -> GPT-5.5
  • Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
  • GPT-5.5 is $10/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • GPT-5.5 adds Code execution in local capability data.

Specs

Specification
Released2026-04-232025-10-10
Context window1.05m200k
Parameters
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2025-122024-06

Pricing and availability

Pricing attributeGPT-5.5o3 Deep Research
Input price
0-272K input tokens
$5/1M tokens
Standard GPT-5.5 token pricing before the long-context surcharge threshold.
272K+ input tokens
$8/1M tokens
Long-context surcharge applies above 272K input tokens for the full session.
$10/1M tokens
Output price
0-272K input tokens
$30/1M tokens
Standard GPT-5.5 token pricing before the long-context surcharge threshold.
272K+ input tokens
$36/1M tokens
Long-context surcharge applies above 272K input tokens for the full session.
$40/1M tokens
Providers

Capabilities

CapabilityGPT-5.5o3 Deep Research
VisionYesYes
MultimodalYesYes
ReasoningYesYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesNo
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

No shared benchmark scores are currently available for this pair.

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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.