Gemini 2.5 Pro vs GPT-5.5 Instant
Wins 1 of 8 areas
Long documents
Wins 6 of 8 areas
Coding · Agents · Reasoning · Facts · Math · Following instructions
GPT-5.5 Instant is the stronger all-rounder.Gemini 2.5 Pro is cheaper and better at long documents.
Scores updated · 24 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 software03GPT-5.5 Instant3 of 3 tests
- AgentsCarrying out multi-step tasks on its own02GPT-5.5 Instant2 of 3 tests · 1 tie
- ReasoningHard problems that need careful thinking02GPT-5.5 Instant2 of 3 tests · 1 tie
- MathCompetition and research-level math02GPT-5.5 Instant2 of 2 tests
- FactsGetting facts right instead of making them up12GPT-5.5 Instant2 of 3 tests
- Following instructionsDoing exactly what it is asked01GPT-5.5 Instant1 of 1 test
- Long documentsFinding answers in very long texts10Gemini 2.5 Pro1 of 1 test
- Images and chartsUnderstanding pictures, charts and video11Even1 each
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.
Gemini 2.5 Pro costs 68% 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 GPT-5.5 Instant pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+25.6points ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+22.8points ahead
- Hard command-line tasks in a real terminalTerminal-Bench Hard+15.9points ahead
Where Gemini 2.5 Pro pulls ahead
- Short factual questions, answered correctlySimpleQA Verified+18points ahead
- Reasons across sets of long documentsAA-LCR+2.7points ahead
Every test, side by side
All 24 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-5.5 Instant
- Terminal-Bench HardGPT-5.5 Instant by 15.926.542.4+15.9
- Terminal-Bench 2.1GPT-5.5 Instant by 6.328.534.8+6.3
- SciCodeGPT-5.5 Instant by 6.246.352.5+6.2
AgentsGPT-5.5 Instant
- Terminal-Bench 4.0GPT-5.5 Instant by 12.6012.6+12.6
- τ-Bench V3 · BankingGPT-5.5 Instant by 2.19.711.8+2.1
- GDPValtie00tie
ReasoningGPT-5.5 Instant
- Humanity's Last ExamGPT-5.5 Instant by 3.61821.6+3.6
- GPQA DiamondGPT-5.5 Instant by 183.684.6+1
- CritPttie2.62.6tie
FactsGPT-5.5 Instant
- AA-Omniscience · Non-hallucinationGPT-5.5 Instant by 25.69.134.7+25.6
- SimpleQA VerifiedGemini 2.5 Pro by 185638+18
- AA-Omniscience · AccuracyGPT-5.5 Instant by 7.23946.3+7.2
Images and chartsEven
- LMArena · VisionGemini 2.5 Pro by 13 rating points12631250+13 rating
- MMMU-ProGPT-5.5 Instant by 1.174.976+1.1
MathGPT-5.5 Instant
- FrontierMath Tier 4GPT-5.5 Instant by 2.402.4+2.4
- FrontierMath Tiers 1-3 (v2)GPT-5.5 Instant by 1.724.626.3+1.7
Following instructionsGPT-5.5 Instant
- IFBenchGPT-5.5 Instant by 22.848.771.5+22.8
Other results6 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.
- AA-OmniscienceGPT-5.5 Instant by 27.5-16.411.2+27.5
- AA Agentic IndexGPT-5.5 Instant by 15.73.519.2+15.7
- AA IntelligenceGPT-5.5 Instant by 7.71522.7+7.7
- Artificial Analysis Coding IndexGemini 2.5 Pro by 7.346.739.4+7.3
- τ²-Bench Telecom (AA run)Gemini 2.5 Pro by 4.754.149.4+4.7
- AIME 2025Gemini 2.5 Pro by 1.88381.2+1.8
Questions people ask
Which is better, Gemini 2.5 Pro or GPT-5.5 Instant?
GPT-5.5 Instant wins six of the eight areas we test: coding, agents, reasoning, facts, math and following instructions. Gemini 2.5 Pro wins long documents, and costs 68% less. They are level on images and charts.
Which is better for coding?
GPT-5.5 Instant. It wins 3 of the 3 coding tests both models report; Gemini 2.5 Pro wins none.
Which is cheaper?
Gemini 2.5 Pro costs $1.25 per million input tokens and $10.00 per million output tokens; GPT-5.5 Instant costs $5.00 and $30.00. That makes Gemini 2.5 Pro about 68% cheaper for the same work.
How do you compare the two?
We use the 24 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 6 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.