Both are Anthropic models. Claude Opus 5 is the newer, generally stronger default; reach for Claude Sonnet 4.5 when its lower price or a specific cost or latency profile matters more than the latest capabilities.
Claude Opus 5 and Claude Sonnet 4.5 are both Anthropic models, so the real question is not which lab to trust but which tier fits your workload and budget. Claude Opus 5 is anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences
Price: Claude Sonnet 4.5 is about 1.7× cheaper on input ($3/$15 per 1M tokens vs $5/$25 per 1M tokens) — modest, but it adds up at steady volume.
Context window: Claude Opus 5 holds 5× more — 1M (~1,500 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: Claude Opus 5 is the newer model by about 10 months (released July 24, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Opus 5
Claude Sonnet 4.5
Provider
Anthropic (US)
Anthropic (US)
Released
July 24, 2026
September 29, 2025
Context window
1M (~1,500 pages)
200K (~300 pages)
Price (in/out)
$5/$25 per 1M tokens
$3/$15 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
77.2%
MRCR v2 @ 1M
Not published
Not published
Who wins what
Frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1: Claude Opus 5 — Claude Sonnet 4.5 is comparatively weak here — superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price
Agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures): Claude Opus 5 — Claude Sonnet 4.5 is comparatively weak here — capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard
Computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost: Claude Opus 5 — Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak — and it carries the larger 1M context.
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch: Claude Sonnet 4.5 — Claude Opus 5 is comparatively weak here — all launch benchmarks are Anthropic-reported and not yet independently reproduced
Computer use and GUI automation (61.4% OSWorld at launch): Claude Sonnet 4.5 — September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded — and it runs cheaper at $3/$15 per 1M tokens.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks: Claude Sonnet 4.5 — Claude Opus 5 is comparatively weak here — behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account
Lowest cost at scale: Claude Sonnet 4.5 — At $3/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: Claude Opus 5 — Its 1M window is about 5× larger than Claude Sonnet 4.5's 200K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Claude Sonnet 4.5 — At $3/$15 per 1M tokens it undercuts Claude Opus 5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Claude Opus 5 — Larger 1M window fits more in one prompt.
Anyone whose priority is frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1: Claude Opus 5 — It is specifically built for that.
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 — That is its strongest area.
Claude Opus 5: where it fits
Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Released July 24, 2026 by Anthropic, it is built for frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1, agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures), computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost, and a native effort setting (low, medium, high, xhigh, max) that trades token cost against capability on a single model.
Its trade-offs are real: behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account, all launch benchmarks are Anthropic-reported and not yet independently reproduced, no published SWE-Bench Verified score, so head-to-head coding comparisons rely on Anthropic's own benchmark suite, and fast mode's throughput costs double the base price ($10/$50 per 1M). At $5 in / $25 out per million tokens, it sits in the premium price band.
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: 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.
The bottom line for this matchup
Because Claude Opus 5 and Claude Sonnet 4.5 come from the same lab (Anthropic), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. Claude Opus 5 is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to Claude Opus 5 and drop down only with a concrete reason.
Frequently asked questions
Is Claude Opus 5 or Claude Sonnet 4.5 better for coding?
Public SWE-Bench figures are not available for Claude Opus 5, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 5 leans toward frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1 while Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 5 or Claude Sonnet 4.5?
Claude Sonnet 4.5 is cheaper — $5/$25 per 1M tokens vs $3/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Claude Opus 5 — 1M vs 200K, about 5× larger. Useful only if the model actually reasons over the full window, which not all do.
Should I upgrade from Claude Sonnet 4.5 to Claude Opus 5?
Since both are Anthropic models, the newer one (Claude Opus 5) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, Claude Opus 5 or Claude Sonnet 4.5?
Claude Opus 5 — released July 24, 2026, about 10 months after Claude Sonnet 4.5.
Claude Opus 5 vs Claude Sonnet 4.5
Anthropic · US | Anthropic · US · Updated June 2026
Quick verdict
Both are Anthropic models. Claude Opus 5 is the newer, generally stronger default; reach for Claude Sonnet 4.5 when its lower price or a specific cost or latency profile matters more than the latest capabilities.
Claude Opus 5 and Claude Sonnet 4.5 are both Anthropic models, so the real question is not which lab to trust but which tier fits your workload and budget. Claude Opus 5 is anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences at a glance
▸Price: Claude Sonnet 4.5 is about 1.7× cheaper on input ($3/$15 per 1M tokens vs $5/$25 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: Claude Opus 5 holds 5× more — 1M (~1,500 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: Claude Opus 5 is the newer model by about 10 months (released July 24, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Opus 5
Claude Sonnet 4.5
Provider
Anthropic (US)
Anthropic (US)
Released
July 24, 2026
September 29, 2025
Context window
1M (~1,500 pages)
200K (~300 pages)
Price (in/out)
$5/$25 per 1M tokens
$3/$15 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
77.2%
MRCR v2 @ 1M
Not published
Not published
Who wins what
Frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1
Claude Opus 5
Claude Sonnet 4.5 is comparatively weak here — superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price
Agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures)
Claude Opus 5
Claude Sonnet 4.5 is comparatively weak here — capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard
Computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost
Claude Opus 5
Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak — and it carries the larger 1M context.
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch
Claude Sonnet 4.5
Claude Opus 5 is comparatively weak here — all launch benchmarks are Anthropic-reported and not yet independently reproduced
Computer use and GUI automation (61.4% OSWorld at launch)
Claude Sonnet 4.5
September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded — and it runs cheaper at $3/$15 per 1M tokens.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks
Claude Sonnet 4.5
Claude Opus 5 is comparatively weak here — behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account
Lowest cost at scale
Claude Sonnet 4.5
At $3/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Claude Opus 5
Its 1M window is about 5× larger than Claude Sonnet 4.5's 200K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Claude Sonnet 4.5
At $3/$15 per 1M tokens it undercuts Claude Opus 5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Claude Opus 5
Larger 1M window fits more in one prompt.
Anyone whose priority is frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1
→ Claude Opus 5
It is specifically built for that.
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
That is its strongest area.
Claude Opus 5: where it fits
Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Released July 24, 2026 by Anthropic, it is built for frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1, agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures), computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost, and a native effort setting (low, medium, high, xhigh, max) that trades token cost against capability on a single model.
Its trade-offs are real: behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account, all launch benchmarks are Anthropic-reported and not yet independently reproduced, no published SWE-Bench Verified score, so head-to-head coding comparisons rely on Anthropic's own benchmark suite, and fast mode's throughput costs double the base price ($10/$50 per 1M). At $5 in / $25 out per million tokens, it sits in the premium price band.
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: 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.
The bottom line for this matchup
Because Claude Opus 5 and Claude Sonnet 4.5 come from the same lab (Anthropic), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. Claude Opus 5 is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to Claude Opus 5 and drop down only with a concrete reason.
Want both Claude Opus 5 and Claude Sonnet 4.5 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.
Is Claude Opus 5 or Claude Sonnet 4.5 better for coding?
Public SWE-Bench figures are not available for Claude Opus 5, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 5 leans toward frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1 while Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 5 or Claude Sonnet 4.5?
Claude Sonnet 4.5 is cheaper — $5/$25 per 1M tokens vs $3/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Claude Opus 5 — 1M vs 200K, about 5× larger. Useful only if the model actually reasons over the full window, which not all do.
Should I upgrade from Claude Sonnet 4.5 to Claude Opus 5?
Since both are Anthropic models, the newer one (Claude Opus 5) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, Claude Opus 5 or Claude Sonnet 4.5?
Claude Opus 5 — released July 24, 2026, about 10 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.