Claude Opus 4.8 vs GPT-5.5 Instant
Wins 7 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Long documents
Wins 1 of 8 areas
Following instructions
Claude Opus 4.8 is the stronger all-rounder.GPT-5.5 Instant is better at following instructions.
Scores updated · 25 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 software30Claude Opus 4.83 of 3 tests
- AgentsCarrying out multi-step tasks on its own30Claude Opus 4.83 of 3 tests
- ReasoningHard problems that need careful thinking30Claude Opus 4.83 of 3 tests
- FactsGetting facts right instead of making them up30Claude Opus 4.83 of 3 tests
- Images and chartsUnderstanding pictures, charts and video20Claude Opus 4.82 of 2 tests
- MathCompetition and research-level math20Claude Opus 4.82 of 2 tests
- Long documentsFinding answers in very long texts10Claude Opus 4.81 of 1 test
- Following instructionsDoing exactly what it is asked01GPT-5.5 Instant1 of 1 test
Long documents and following instructions 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 Opus 4.8 costs 14% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Opus 4.8 pulls ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+53.7points ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+53.7points ahead
- Command-line tasks in a real terminalTerminal-Bench 2.1+49.8points ahead
Where GPT-5.5 Instant pulls ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+9.3points ahead
Every test, side by side
All 25 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 4.8
- Terminal-Bench 2.1Claude Opus 4.8 by 49.884.634.8+49.8
- Terminal-Bench HardClaude Opus 4.8 by 15.958.342.4+15.9
- SciCodeClaude Opus 4.8 by 1.954.452.5+1.9
AgentsClaude Opus 4.8
- GDPValClaude Opus 4.8 by 47.847.80+47.8
- τ-Bench V3 · BankingClaude Opus 4.8 by 22.434.211.8+22.4
- Terminal-Bench 4.0Claude Opus 4.8 by 9.121.712.6+9.1
ReasoningClaude Opus 4.8
- Humanity's Last ExamClaude Opus 4.8 by 27.148.721.6+27.1
- CritPtClaude Opus 4.8 by 18.320.92.6+18.3
- GPQA DiamondClaude Opus 4.8 by 7.49284.6+7.4
FactsClaude Opus 4.8
- AA-Omniscience · Non-hallucinationClaude Opus 4.8 by 2660.734.7+26
- SimpleQA VerifiedClaude Opus 4.8 by 155338+15
- AA-Omniscience · AccuracyClaude Opus 4.8 by 2.548.846.3+2.5
Images and chartsClaude Opus 4.8
- CharXiv (RQ)Claude Opus 4.8 by 8.389.981.6+8.3
- LMArena · VisionClaude Opus 4.8 by 45 rating points12951250+45 rating
MathClaude Opus 4.8
- FrontierMath Tier 4Claude Opus 4.8 by 53.756.12.4+53.7
- FrontierMath Tiers 1-3 (v2)Claude Opus 4.8 by 53.78026.3+53.7
Following instructionsGPT-5.5 Instant
- IFBenchGPT-5.5 Instant by 9.362.271.5+9.3
Other results7 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-Bench Telecom (AA run)Claude Opus 4.8 by 4594.449.4+45
- Artificial Analysis Coding IndexClaude Opus 4.8 by 34.974.339.4+34.9
- AA Agentic IndexClaude Opus 4.8 by 23.442.619.2+23.4
- AA IntelligenceClaude Opus 4.8 by 19.141.822.7+19.1
- AA-OmniscienceClaude Opus 4.8 by 17.628.811.2+17.6
- HealthBench ProfessionalClaude Opus 4.8 by 17.455.838.4+17.4
- HealthBenchClaude Opus 4.8 by 7.959.351.4+7.9
Questions people ask
Which is better, Claude Opus 4.8 or GPT-5.5 Instant?
Claude Opus 4.8 wins seven of the eight areas we test: coding, agents, reasoning, facts, images and charts, math and long documents. GPT-5.5 Instant wins following instructions.
Which is better for coding?
Claude Opus 4.8. It wins 3 of the 3 coding tests both models report; GPT-5.5 Instant wins none.
Which is cheaper?
Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens; GPT-5.5 Instant costs $5.00 and $30.00. That makes Claude Opus 4.8 about 14% cheaper for the same work.
How do you compare the two?
We use the 25 benchmark tests both models have published scores on. The verdict counts the 18 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 7 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.