Claude Opus 4.1 vs Claude Sonnet 4.5
Wins 2 of 8 areas
Facts · Long documents
Wins 4 of 8 areas
Coding · Agents · Reasoning · Math
Claude Sonnet 4.5 wins more areas, narrowly.Claude Opus 4.1 is better at facts.
Scores updated · 33 tests both models report · How we compare
Where each one wins
Tests won in each of the eight areas we test. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software03Claude Sonnet 4.53 of 4 tests · 1 tie
- ReasoningHard problems that need careful thinking03Claude Sonnet 4.53 of 3 tests
- AgentsCarrying out multi-step tasks on its own02Claude Sonnet 4.52 of 2 tests
- MathCompetition and research-level math01Claude Sonnet 4.51 of 2 tests · 1 tie
- FactsGetting facts right instead of making them up10Claude Opus 4.11 of 2 tests · 1 tie
- Long documentsFinding answers in very long texts10Claude Opus 4.11 of 1 test
- Images and chartsUnderstanding pictures, charts and video00Even0 each · 1 tie
- Following instructionsDoing exactly what it is asked11Even1 each
Images and charts and long documents rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
Claude Sonnet 4.5 costs 80% less for the same work.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where Claude Sonnet 4.5 pulls ahead
- Completes tasks by operating a computer desktopOSWorld-Verified+17points ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+11.3points ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+5.3points ahead
Where Claude Opus 4.1 pulls ahead
- Short factual questions, answered correctlySimpleQA Verified+4.1points ahead
- Reasons across sets of long documentsAA-LCR+3.7points ahead
- Keeps track of context across a multi-turn chatMulti-Challenge+1.9points ahead
Every test, side by side
All 33 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Sonnet 4.5
- SciCodeClaude Sonnet 4.5 by 4.840.945.7+4.8
- SWE-bench VerifiedClaude Sonnet 4.5 by 2.774.577.2+2.7
- Terminal-Bench HardClaude Sonnet 4.5 by 1.334.335.6+1.3
- LMArena · WebDevtie13891393tie
AgentsClaude Sonnet 4.5
- OSWorld-VerifiedClaude Sonnet 4.5 by 1744.461.4+17
- MCP AtlasClaude Sonnet 4.5 by 2.940.943.8+2.9
ReasoningClaude Sonnet 4.5
- Humanity's Last ExamClaude Sonnet 4.5 by 5.312.517.8+5.3
- GPQA DiamondClaude Sonnet 4.5 by 2.580.983.4+2.5
- CritPtClaude Sonnet 4.5 by 1.101.1+1.1
FactsClaude Opus 4.1
- SimpleQA VerifiedClaude Opus 4.1 by 4.134.830.7+4.1
- Vectara HHEM hallucination ratelower is bettertie11.812tie
MathClaude Sonnet 4.5
- FrontierMath Tiers 1-3 (v2)Claude Sonnet 4.5 by 11.312.623.9+11.3
- FrontierMath Tier 4tie2.42.4tie
Following instructionsEven
- IFBenchClaude Sonnet 4.5 by 1.955.457.3+1.9
- Multi-ChallengeClaude Opus 4.1 by 1.957.255.3+1.9
Other results16 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- τ²-BenchClaude Sonnet 4.5 by 26.571.598+26.5
- Artificial Analysis Coding IndexClaude Sonnet 4.5 by 15.636.552.1+15.6
- TAU-bench (airline)Claude Sonnet 4.5 by 145670+14
- AIME 2025Claude Sonnet 4.5 by 97887+9
- Terminal-BenchClaude Sonnet 4.5 by 6.743.350+6.7
- τ²-Bench Telecom (AA run)Claude Sonnet 4.5 by 6.771.478.1+6.7
- TAU-bench (retail)Claude Sonnet 4.5 by 3.882.486.2+3.8
- Terminal-Bench 2.0Claude Sonnet 4.5 by 3.546.550+3.5
- vectara_answer_rateClaude Sonnet 4.5 by 3.292.495.6+3.2
- AA IntelligenceClaude Opus 4.1 by 2.122.820.7+2.1
- SWE-bench Verified (hard subset)Claude Sonnet 4.5 by 1.543.845.3+1.5
- τ²-Bench (Retail)tie86.886.2tie
- MMMLUtie89.589.1tie
- vectara_factual_consistencytie88.288tie
- vectara_avg_summary_lengthtie129.1127.8tie
- frontiermath_tier_4_v1tie4.24.2tie
Questions people ask
Which is better, Claude Opus 4.1 or Claude Sonnet 4.5?
Claude Sonnet 4.5 wins four of the eight areas we test: coding, agents, reasoning and math. Claude Opus 4.1 wins facts and long documents. They are level on images and charts and following instructions.
Which is better for coding?
Claude Sonnet 4.5. It wins 3 of the 4 coding tests both models report; Claude Opus 4.1 wins none, and 1 is a tie.
Which is cheaper?
Claude Opus 4.1 costs $15.00 per million input tokens and $75.00 per million output tokens; Claude Sonnet 4.5 costs $3.00 and $15.00. That makes Claude Sonnet 4.5 about 80% cheaper for the same work.
How do you compare the two?
We use the 33 benchmark tests both models have published scores on. The verdict counts the 17 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 16 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.