Claude Opus 5 vs Claude Sonnet 5
Claude Opus 5 vs Claude Sonnet 5
Opus 5 wins every comparison that resolves as a real gap, and never trails. DeepSWE (74.0 vs 54.0), Humanity's Last Exam without tools (54.9 vs 41.3) and — since 2026-10-08 — Terminal-Bench 4.0 (53.54 vs 9.6, both vals.ai mini-swe-agent runs at max effort) are three confirmed real gaps, independently run on both sides, none close — the smallest margin is 13.6 points against a 2-point noise band, and Terminal-Bench 4.0's 44.0-point gap is the largest resolved gap in any verdict on this site against its 12.4-point band. LiveBench was a third until 2026-10-02: its 80.1 vs 76.0 was a 4.1-point lead, but Opus 5's row is the board's Max Effort run while Sonnet 5's is an xHigh Effort run, and more thinking is not a free upgrade, so that comparison no longer counts. HLE is tier-matched, max against max. DeepSWE is not matched — neither row records a tier — so that 20-point gap rests on the two boards' default configurations. AA-AnalystAgent, added 2026-09-29, is the one resolved comparison that is not a real gap: 53.75 vs 46.25 pass^5, both Artificial Analysis runs, a 7.5-point lead that sits inside that benchmark's 11.2-point noise band and so reads as a tie. SWE-bench Verified (97.0 vs 79.6), GPQA Diamond (93.43 vs 88.89) and, since 2026-09-29, LiveCodeBench (89.03 vs 82.43) count as neither real nor tied: each of those benchmarks is graded saturated on this site, so a score there reflects a ceiling, not evenly matched models — LiveCodeBench was a fourth real gap until that call. Terminal-Bench 2.1 is independently run on both sides but through different evaluation harnesses (Artificial Analysis for Opus 5, tbench.ai's official board for Sonnet 5) and at different effort tiers, so it fails two setup checks at once — not a fair comparison even though neither number is a vendor claim; vals.ai's single-harness runs of both read 84.64 vs 74.53, 10.1 points apart, inside the 10.6 band. OSWorld 2.0, added 2026-10-08, looks like a fourth blowout (77.67 vs 57.0 on the v2.1 full slice) but stays unverified rather than real: Opus 5's number is the benchmark authors' own independent run while Sonnet 5's is Anthropic's own claimed number, so only one side of the comparison has been independently measured. Three benchmarks don't yield a comparable line at all: Agents' Last Exam and ARC-AGI-2 are tracked for Opus 5 only, Toolathlon-Verified for Sonnet 5 only. Sonnet 5's case is price — $2/$10 versus Opus 5's $5/$25, a 60% discount on both input and output — though Sonnet 5's newer tokenizer produces roughly 30% more tokens for the same text, so the effective cost gap runs smaller than the sticker prices alone suggest.
Claude Opus 5 vs Claude Sonnet 5: benchmark by benchmark
Across 16 rows comparing Claude Opus 5 and Claude Sonnet 5: 3 rows carry a confirmed real gap, 1 row lands inside the noise band, and 12 rows carry other caveats — unverified, tainted, or run on mismatched tool setups. Read each row’s Signal label before ranking Claude Opus 5 against Claude Sonnet 5.
Who should pick Claude Opus 5, and who should pick Claude Sonnet 5
- Coding or reasoning work where capability is the constraint → Claude Opus 5 (three confirmed real gaps, 13.6 to 44.0 points each, every number independently run on both sides — neither close)
- Budget-constrained or high-volume workloads → Claude Sonnet 5.5 (Sonnet 5.5 ships at Sonnet 5's unchanged $2/$10 list price, and its independently-run HLE no-tools score is 55.0 against Sonnet 5's 41.3 — the budget tier moved up around Sonnet 5, so the pick inherits the upgrade rather than the older model)
- An existing Sonnet integration already in production → Claude Sonnet 5 (hedged pick: Opus 5's wins are real and not marginal, but if the switching cost exceeds what the performance gap is worth to your workload, that's a legitimate reason to stay put — though Sonnet 5.5 is a same-price drop-in within the same line)
Claude Opus 5 vs Claude Sonnet 5 pricing
| Input / 1M tokens | $5.00 | $2.00 |
| Output / 1M tokens | $25.00 | $10.00 |
Claude Opus 5 vs Claude Sonnet 5 FAQ
Is Claude Opus 5 better than Claude Sonnet 5?
Opus 5 wins every comparison that resolves as a real gap, and never trails. DeepSWE (74.0 vs 54.0), Humanity's Last Exam without tools (54.9 vs 41.3) and — since 2026-10-08 — Terminal-Bench 4.0 (53.54 vs 9.6, both vals.ai mini-swe-agent runs at max effort) are three confirmed real gaps, independently run on both sides, none close — the smallest margin is 13.6 points against a 2-point noise band, and Terminal-Bench 4.0's 44.0-point gap is the largest resolved gap in any verdict on this site against its 12.4-point band. LiveBench was a third until 2026-10-02: its 80.1 vs 76.0 was a 4.1-point lead, but Opus 5's row is the board's Max Effort run while Sonnet 5's is an xHigh Effort run, and more thinking is not a free upgrade, so that comparison no longer counts. HLE is tier-matched, max against max. DeepSWE is not matched — neither row records a tier — so that 20-point gap rests on the two boards' default configurations. AA-AnalystAgent, added 2026-09-29, is the one resolved comparison that is not a real gap: 53.75 vs 46.25 pass^5, both Artificial Analysis runs, a 7.5-point lead that sits inside that benchmark's 11.2-point noise band and so reads as a tie. SWE-bench Verified (97.0 vs 79.6), GPQA Diamond (93.43 vs 88.89) and, since 2026-09-29, LiveCodeBench (89.03 vs 82.43) count as neither real nor tied: each of those benchmarks is graded saturated on this site, so a score there reflects a ceiling, not evenly matched models — LiveCodeBench was a fourth real gap until that call. Terminal-Bench 2.1 is independently run on both sides but through different evaluation harnesses (Artificial Analysis for Opus 5, tbench.ai's official board for Sonnet 5) and at different effort tiers, so it fails two setup checks at once — not a fair comparison even though neither number is a vendor claim; vals.ai's single-harness runs of both read 84.64 vs 74.53, 10.1 points apart, inside the 10.6 band. OSWorld 2.0, added 2026-10-08, looks like a fourth blowout (77.67 vs 57.0 on the v2.1 full slice) but stays unverified rather than real: Opus 5's number is the benchmark authors' own independent run while Sonnet 5's is Anthropic's own claimed number, so only one side of the comparison has been independently measured. Three benchmarks don't yield a comparable line at all: Agents' Last Exam and ARC-AGI-2 are tracked for Opus 5 only, Toolathlon-Verified for Sonnet 5 only. Sonnet 5's case is price — $2/$10 versus Opus 5's $5/$25, a 60% discount on both input and output — though Sonnet 5's newer tokenizer produces roughly 30% more tokens for the same text, so the effective cost gap runs smaller than the sticker prices alone suggest.
Which is cheaper, Claude Opus 5 or Claude Sonnet 5?
Claude Sonnet 5 costs less per output token ($10.00 vs $25.00 per 1M tokens, official listed rates).
How big is the real gap between Opus 5 and Sonnet 5?
Two confirmed real gaps, both independently run on both sides: DeepSWE at 74.0 vs 54.0 and Humanity's Last Exam without tools at 54.9 vs 41.3. The smallest margin is 13.6 points against a 2-point noise band, so neither is close.
Should a new project start on Sonnet 5?
No — start on Claude Sonnet 5.5. It ships at Sonnet 5's unchanged $2/$10 list price, and its independently-run HLE no-tools score is 55.0 against Sonnet 5's 41.3. Sonnet 5's page stays live here with its record intact, but this site computes Sonnet 5.5 as its successor.
Why doesn't the LiveBench comparison count?
Its 80.1 vs 76.0 was a 4.1-point lead until 2026-10-02, when this site started requiring effort-matched rows: Opus 5's row is the board's Max Effort run while Sonnet 5's is an xHigh Effort run, and more thinking is not a free upgrade. The comparison now reads setup-dependent rather than a win.
Is the DeepSWE comparison effort-matched?
No — neither row records a tier, so the 20-point gap rests on the two boards' default configurations, and the verdict says so. HLE is the tier-matched one: max against max, 54.9 vs 41.3.