Pick Claude Sonnet 5 for agentic workflows that plan, use tools, and run autonomously or multi-step coding, debugging, and tool use. Pick GPT-5.5 for terminal, cli and computer-use automation or long-horizon tool sequencing. On a tight budget at scale, Claude Sonnet 5 is the value pick.
Claude Sonnet 5 (Anthropic) and GPT-5.5 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Sonnet 5 is anthropic's most agentic Sonnet, with near-Opus-4.8 performance at Sonnet prices; the default model on Free and Pro. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Their biggest split is price, and the breakdown below shows exactly how that plays out for your workload.
Key differences
Price: Claude Sonnet 5 is about 1.7× cheaper on input ($3/$15 per 1M tokens vs $5/$30 per 1M tokens) — modest, but it adds up at steady volume.
Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
Recency: Claude Sonnet 5 is the newer model by about 2 months (released June 30, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Sonnet 5
GPT-5.5
Provider
Anthropic (US)
OpenAI (US)
Released
June 30, 2026
April 23, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$3/$15 per 1M tokens
$5/$30 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic workflows that plan, use tools, and run autonomously: Claude Sonnet 5 — A core design strength of Claude Sonnet 5.
Multi-step coding, debugging, and tool use: Claude Sonnet 5 — A core design strength of Claude Sonnet 5.
Everyday professional and knowledge work: Claude Sonnet 5 — A core design strength of Claude Sonnet 5.
Terminal, CLI and computer-use automation: GPT-5.5 — A core design strength of GPT-5.5.
Long-horizon tool sequencing: GPT-5.5 — A core design strength of GPT-5.5.
Strong agentic coding and reasoning: GPT-5.5 — A core design strength of GPT-5.5.
Lowest cost at scale: Claude Sonnet 5 — At $3/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume: Claude Sonnet 5 — At $3/$15 per 1M tokens it undercuts GPT-5.5, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is agentic workflows that plan, use tools, and run autonomously: Claude Sonnet 5 — It is specifically built for that.
Anyone whose priority is terminal, cli and computer-use automation: GPT-5.5 — That is its strongest area.
Claude Sonnet 5: where it fits
Anthropic's most agentic Sonnet, with near-Opus-4.8 performance at Sonnet prices; the default model on Free and Pro. Released June 30, 2026 by Anthropic, it is built for agentic workflows that plan, use tools, and run autonomously, multi-step coding, debugging, and tool use, everyday professional and knowledge work, and long-document analysis and reasoning.
Its trade-offs are real: lower peak accuracy than Opus 4.8 on the hardest tasks, and an updated tokenizer that can use 1.0-1.35x more tokens for the same text. At $3 in / $15 out per million tokens, it sits in the mid price band.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Sonnet 5 and GPT-5.5 overlap enough that the right pick depends on your specific job. Claude Sonnet 5 costs less per token; and each leads in its own area — Claude Sonnet 5 for agentic workflows that plan, use tools, and run autonomously, GPT-5.5 for terminal, cli and computer-use automation. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Sonnet 5 or GPT-5.5 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Sonnet 5 leans toward agentic workflows that plan, use tools, and run autonomously while GPT-5.5 leans toward terminal, cli and computer-use automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Sonnet 5 or GPT-5.5?
Claude Sonnet 5 is cheaper — $3/$15 per 1M tokens vs $5/$30 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Sonnet 5 and GPT-5.5 together?
Yes — a multi-model platform like LumiChats gives you Claude Sonnet 5, GPT-5.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Sonnet 5 or GPT-5.5?
Claude Sonnet 5 — released June 30, 2026, about 2 months after GPT-5.5.
Claude Sonnet 5 vs GPT-5.5
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Sonnet 5 for agentic workflows that plan, use tools, and run autonomously or multi-step coding, debugging, and tool use. Pick GPT-5.5 for terminal, cli and computer-use automation or long-horizon tool sequencing. On a tight budget at scale, Claude Sonnet 5 is the value pick.
Claude Sonnet 5 (Anthropic) and GPT-5.5 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Sonnet 5 is anthropic's most agentic Sonnet, with near-Opus-4.8 performance at Sonnet prices; the default model on Free and Pro. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Their biggest split is price, and the breakdown below shows exactly how that plays out for your workload.
Key differences at a glance
▸Price: Claude Sonnet 5 is about 1.7× cheaper on input ($3/$15 per 1M tokens vs $5/$30 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
▸Recency: Claude Sonnet 5 is the newer model by about 2 months (released June 30, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Sonnet 5
GPT-5.5
Provider
Anthropic (US)
OpenAI (US)
Released
June 30, 2026
April 23, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$3/$15 per 1M tokens
$5/$30 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic workflows that plan, use tools, and run autonomously
Claude Sonnet 5
A core design strength of Claude Sonnet 5.
Multi-step coding, debugging, and tool use
Claude Sonnet 5
A core design strength of Claude Sonnet 5.
Everyday professional and knowledge work
Claude Sonnet 5
A core design strength of Claude Sonnet 5.
Terminal, CLI and computer-use automation
GPT-5.5
A core design strength of GPT-5.5.
Long-horizon tool sequencing
GPT-5.5
A core design strength of GPT-5.5.
Strong agentic coding and reasoning
GPT-5.5
A core design strength of GPT-5.5.
Lowest cost at scale
Claude Sonnet 5
At $3/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Claude Sonnet 5
At $3/$15 per 1M tokens it undercuts GPT-5.5, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is agentic workflows that plan, use tools, and run autonomously
→ Claude Sonnet 5
It is specifically built for that.
Anyone whose priority is terminal, cli and computer-use automation
→ GPT-5.5
That is its strongest area.
Claude Sonnet 5: where it fits
Anthropic's most agentic Sonnet, with near-Opus-4.8 performance at Sonnet prices; the default model on Free and Pro. Released June 30, 2026 by Anthropic, it is built for agentic workflows that plan, use tools, and run autonomously, multi-step coding, debugging, and tool use, everyday professional and knowledge work, and long-document analysis and reasoning.
Its trade-offs are real: lower peak accuracy than Opus 4.8 on the hardest tasks, and an updated tokenizer that can use 1.0-1.35x more tokens for the same text. At $3 in / $15 out per million tokens, it sits in the mid price band.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Sonnet 5 and GPT-5.5 overlap enough that the right pick depends on your specific job. Claude Sonnet 5 costs less per token; and each leads in its own area — Claude Sonnet 5 for agentic workflows that plan, use tools, and run autonomously, GPT-5.5 for terminal, cli and computer-use automation. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Sonnet 5 and GPT-5.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Sonnet 5 leans toward agentic workflows that plan, use tools, and run autonomously while GPT-5.5 leans toward terminal, cli and computer-use automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Sonnet 5 or GPT-5.5?
Claude Sonnet 5 is cheaper — $3/$15 per 1M tokens vs $5/$30 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Sonnet 5 and GPT-5.5 together?
Yes — a multi-model platform like LumiChats gives you Claude Sonnet 5, GPT-5.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Sonnet 5 or GPT-5.5?
Claude Sonnet 5 — released June 30, 2026, about 2 months after GPT-5.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.