Pick Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch or computer use and gui automation (61.4% osworld at launch). Pick GPT-6 Sol for openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment or openai says it makes about half as many mistakes as gpt-5.6 sol. On a tight budget at scale, GPT-6 Sol is the value pick.
Claude Sonnet 4.5 (Anthropic) and GPT-6 Sol (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. GPT-6 Sol is openAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: GPT-6 Sol is about 1.5× cheaper on input ($2/$10 per 1M tokens vs $3/$15 per 1M tokens) — modest, but it adds up at steady volume.
Context window: GPT-6 Sol holds 5.3× more — 1.05M tokens (~1,575 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: GPT-6 Sol is the newer model by about 12 months (released September 22, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Sonnet 4.5
GPT-6 Sol
Provider
Anthropic (US)
OpenAI (US)
Released
September 29, 2025
September 22, 2026
Context window
200K (~300 pages)
1.05M tokens (~1,575 pages)
Price (in/out)
$3/$15 per 1M tokens
$2/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image
SWE-Bench Verified
77.2%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch: Claude Sonnet 4.5 — Claude Sonnet 4.5 lists agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch among its strengths; GPT-6 Sol does not.
Computer use and GUI automation (61.4% OSWorld at launch): Claude Sonnet 4.5 — Claude Sonnet 4.5 lists computer use and GUI automation (61.4% OSWorld at launch) among its strengths; GPT-6 Sol does not.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks: Claude Sonnet 4.5 — Claude Sonnet 4.5 lists long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks among its strengths; GPT-6 Sol does not.
OpenAI's everyday-work tier below GPT-6 Astra, built with the same methods that improved Astra's professional work, factuality, coding, computer use, and alignment: GPT-6 Sol — OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens — and it runs cheaper at $2/$10 per 1M tokens.
OpenAI says it makes about half as many mistakes as GPT-5.6 Sol: GPT-6 Sol — OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens — and it carries the larger 1.05M tokens context.
Priced at half of the GPT-5.6 Sol/Luna generation's rates ($2/$10 vs GPT-5.6 Sol's $5/$30): GPT-6 Sol — At $2/$10 per 1M tokens it undercuts Claude Sonnet 4.5 ($3/$15 per 1M tokens), and that gap compounds at volume.
Lowest cost at scale: GPT-6 Sol — At $2/$10 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: GPT-6 Sol — Its 1.05M tokens window is about 5.3× larger than Claude Sonnet 4.5's 200K, fitting roughly 1,575 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: GPT-6 Sol — At $2/$10 per 1M tokens it undercuts Claude Sonnet 4.5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-6 Sol — Larger 1.05M tokens window fits more in one prompt.
Anyone whose priority is agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch: Claude Sonnet 4.5 — It is specifically built for that.
Anyone whose priority is openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment: GPT-6 Sol — That is its strongest area.
Claude Sonnet 4.5: where it fits
September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Released September 29, 2025 by Anthropic, it is built for agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch, computer use and GUI automation (61.4% OSWorld at launch), long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks, and tracking its own remaining token budget natively, which few models do.
Its trade-offs are real: superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price, capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard, and missing the modern API surface: no adaptive thinking, no effort control, and half the max output of newer Sonnets. At $3 in / $15 out per million tokens, it sits in the mid price band.
GPT-6 Sol: where it fits
OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens. Released September 22, 2026 by OpenAI, it is built for openAI's everyday-work tier below GPT-6 Astra, built with the same methods that improved Astra's professional work, factuality, coding, computer use, and alignment, openAI says it makes about half as many mistakes as GPT-5.6 Sol, priced at half of the GPT-5.6 Sol/Luna generation's rates ($2/$10 vs GPT-5.6 Sol's $5/$30), and 1.05M-token context window, input capped at 922K.
Its trade-offs: more reasoning capability than sibling GPT-6 Luna, but still positioned below flagship GPT-6 Astra, and cache-read pricing ($0.20/MTok) still costlier than Luna's ($0.01/MTok) for high-cache workloads. At $2 in / $10 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Sonnet 4.5 and GPT-6 Sol overlap enough that the right pick depends on your specific job. GPT-6 Sol costs less per token; GPT-6 Sol holds the larger context; and each leads in its own area — Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, GPT-6 Sol for openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Sonnet 4.5 or GPT-6 Sol better for coding?
Public SWE-Bench figures are not available for GPT-6 Sol, so the honest test is your own repository — run an identical real bug through both. By design, Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch while GPT-6 Sol leans toward openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Sonnet 4.5 or GPT-6 Sol?
GPT-6 Sol is cheaper — $3/$15 per 1M tokens vs $2/$10 per 1M tokens, roughly 1.5× apart on input.
Which has the bigger context window?
GPT-6 Sol — 1.05M tokens vs 200K, about 5.3× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Sonnet 4.5 and GPT-6 Sol together?
Yes — a multi-model platform like LumiChats gives you Claude Sonnet 4.5, GPT-6 Sol 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 4.5 or GPT-6 Sol?
GPT-6 Sol — released September 22, 2026, about 12 months after Claude Sonnet 4.5.
Claude Sonnet 4.5 vs GPT-6 Sol
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch or computer use and gui automation (61.4% osworld at launch). Pick GPT-6 Sol for openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment or openai says it makes about half as many mistakes as gpt-5.6 sol. On a tight budget at scale, GPT-6 Sol is the value pick.
Claude Sonnet 4.5 (Anthropic) and GPT-6 Sol (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. GPT-6 Sol is openAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: GPT-6 Sol is about 1.5× cheaper on input ($2/$10 per 1M tokens vs $3/$15 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: GPT-6 Sol holds 5.3× more — 1.05M tokens (~1,575 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: GPT-6 Sol is the newer model by about 12 months (released September 22, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Sonnet 4.5
GPT-6 Sol
Provider
Anthropic (US)
OpenAI (US)
Released
September 29, 2025
September 22, 2026
Context window
200K (~300 pages)
1.05M tokens (~1,575 pages)
Price (in/out)
$3/$15 per 1M tokens
$2/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image
SWE-Bench Verified
77.2%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch
Claude Sonnet 4.5
Claude Sonnet 4.5 lists agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch among its strengths; GPT-6 Sol does not.
Computer use and GUI automation (61.4% OSWorld at launch)
Claude Sonnet 4.5
Claude Sonnet 4.5 lists computer use and GUI automation (61.4% OSWorld at launch) among its strengths; GPT-6 Sol does not.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks
Claude Sonnet 4.5
Claude Sonnet 4.5 lists long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks among its strengths; GPT-6 Sol does not.
OpenAI's everyday-work tier below GPT-6 Astra, built with the same methods that improved Astra's professional work, factuality, coding, computer use, and alignment
GPT-6 Sol
OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens — and it runs cheaper at $2/$10 per 1M tokens.
OpenAI says it makes about half as many mistakes as GPT-5.6 Sol
GPT-6 Sol
OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens — and it carries the larger 1.05M tokens context.
Priced at half of the GPT-5.6 Sol/Luna generation's rates ($2/$10 vs GPT-5.6 Sol's $5/$30)
GPT-6 Sol
At $2/$10 per 1M tokens it undercuts Claude Sonnet 4.5 ($3/$15 per 1M tokens), and that gap compounds at volume.
Lowest cost at scale
GPT-6 Sol
At $2/$10 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-6 Sol
Its 1.05M tokens window is about 5.3× larger than Claude Sonnet 4.5's 200K, fitting roughly 1,575 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-6 Sol
At $2/$10 per 1M tokens it undercuts Claude Sonnet 4.5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-6 Sol
Larger 1.05M tokens window fits more in one prompt.
Anyone whose priority is agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch
→ Claude Sonnet 4.5
It is specifically built for that.
Anyone whose priority is openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment
→ GPT-6 Sol
That is its strongest area.
Claude Sonnet 4.5: where it fits
September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Released September 29, 2025 by Anthropic, it is built for agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch, computer use and GUI automation (61.4% OSWorld at launch), long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks, and tracking its own remaining token budget natively, which few models do.
Its trade-offs are real: superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price, capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard, and missing the modern API surface: no adaptive thinking, no effort control, and half the max output of newer Sonnets. At $3 in / $15 out per million tokens, it sits in the mid price band.
GPT-6 Sol: where it fits
OpenAI's September 22, 2026 mid-tier update — Astra-derived improvements at half the GPT-5.6 Sol price, $2/$10 per million tokens. Released September 22, 2026 by OpenAI, it is built for openAI's everyday-work tier below GPT-6 Astra, built with the same methods that improved Astra's professional work, factuality, coding, computer use, and alignment, openAI says it makes about half as many mistakes as GPT-5.6 Sol, priced at half of the GPT-5.6 Sol/Luna generation's rates ($2/$10 vs GPT-5.6 Sol's $5/$30), and 1.05M-token context window, input capped at 922K.
Its trade-offs: more reasoning capability than sibling GPT-6 Luna, but still positioned below flagship GPT-6 Astra, and cache-read pricing ($0.20/MTok) still costlier than Luna's ($0.01/MTok) for high-cache workloads. At $2 in / $10 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Sonnet 4.5 and GPT-6 Sol overlap enough that the right pick depends on your specific job. GPT-6 Sol costs less per token; GPT-6 Sol holds the larger context; and each leads in its own area — Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, GPT-6 Sol for openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Sonnet 4.5 and GPT-6 Sol 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.
Is Claude Sonnet 4.5 or GPT-6 Sol better for coding?
Public SWE-Bench figures are not available for GPT-6 Sol, so the honest test is your own repository — run an identical real bug through both. By design, Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch while GPT-6 Sol leans toward openai's everyday-work tier below gpt-6 astra, built with the same methods that improved astra's professional work, factuality, coding, computer use, and alignment, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Sonnet 4.5 or GPT-6 Sol?
GPT-6 Sol is cheaper — $3/$15 per 1M tokens vs $2/$10 per 1M tokens, roughly 1.5× apart on input.
Which has the bigger context window?
GPT-6 Sol — 1.05M tokens vs 200K, about 5.3× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Sonnet 4.5 and GPT-6 Sol together?
Yes — a multi-model platform like LumiChats gives you Claude Sonnet 4.5, GPT-6 Sol 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 4.5 or GPT-6 Sol?
GPT-6 Sol — released September 22, 2026, about 12 months after Claude Sonnet 4.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.