Gemini 3.1 Pro vs Step 3.5 Flash
Wins 6 of 7 areas
Coding · Reasoning · Facts · Math · Long documents · Following instructions
Wins 0 of 7 areas
—
Gemini 3.1 Pro is the stronger all-rounder.Step 3.5 Flash is cheaper.
Scores updated · 26 tests both models report · How we compare
Where each one wins
Tests won in each of the seven areas where both have results. 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 software40Gemini 3.1 Pro4 of 4 tests
- ReasoningHard problems that need careful thinking30Gemini 3.1 Pro3 of 3 tests
- MathCompetition and research-level math31Gemini 3.1 Pro3 of 4 tests
- FactsGetting facts right instead of making them up20Gemini 3.1 Pro2 of 2 tests
- Long documentsFinding answers in very long texts10Gemini 3.1 Pro1 of 1 test
- Following instructionsDoing exactly what it is asked10Gemini 3.1 Pro1 of 1 test
- AgentsCarrying out multi-step tasks on its own11Even1 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.
Step 3.5 Flash costs 97% 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 Gemini 3.1 Pro pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+34.8points ahead
- Reasons across sets of long documentsAA-LCR+32points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+31.3points ahead
Where Step 3.5 Flash pulls ahead
- Real work tasks from 44 professionsGDPVal+12.9points ahead
- Olympiad math problems with short answersIMOAnswerBench+4.4points ahead
Every test, side by side
All 26 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGemini 3.1 Pro
- Terminal-Bench HardGemini 3.1 Pro by 26.553.827.3+26.5
- SciCodeGemini 3.1 Pro by 18.358.740.4+18.3
- SWE-bench VerifiedGemini 3.1 Pro by 6.280.674.4+6.2
- LiveCodeBench v6Gemini 3.1 Pro by 5.391.786.4+5.3
AgentsEven
- BrowseCompGemini 3.1 Pro by 16.985.969+16.9
- GDPValStep 3.5 Flash by 12.914.727.6+12.9
ReasoningGemini 3.1 Pro
- Humanity's Last ExamGemini 3.1 Pro by 25.94721.1+25.9
- CritPtGemini 3.1 Pro by 15.217.72.5+15.2
- GPQA DiamondGemini 3.1 Pro by 1194.183.1+11
FactsGemini 3.1 Pro
- AA-Omniscience · Non-hallucinationGemini 3.1 Pro by 34.849.114.3+34.8
- AA-Omniscience · AccuracyGemini 3.1 Pro by 31.354.923.6+31.3
MathGemini 3.1 Pro
- USAMO 2026Gemini 3.1 Pro by 29.874.444.6+29.8
- HMMT Feb. 2026Gemini 3.1 Pro by 8.394.786.4+8.3
- IMOAnswerBenchStep 3.5 Flash by 4.48185.4+4.4
- AIME 2026Gemini 3.1 Pro by 1.698.396.7+1.6
Following instructionsGemini 3.1 Pro
- IFBenchGemini 3.1 Pro by 12.577.164.6+12.5
Other results9 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-OmniscienceGemini 3.1 Pro by 73.731.9-41.8+73.7
- AA Agentic IndexStep 3.5 Flash by 41.710.352+41.7
- Artificial Analysis Coding IndexGemini 3.1 Pro by 37.268.831.6+37.2
- Terminal-Bench 2.0Gemini 3.1 Pro by 17.568.551+17.5
- browsecomp_with_context_managerGemini 3.1 Pro by 16.985.969+16.9
- AA IntelligenceGemini 3.1 Pro by 13.129.716.6+13.1
- MMLU-ProGemini 3.1 Pro by 6.69184.4+6.6
- τ²-Bench Telecom (AA run)Gemini 3.1 Pro by 1.295.694.4+1.2
- HMMT Nov. 2025tie94.894tie
Questions people ask
Which is better, Gemini 3.1 Pro or Step 3.5 Flash?
Gemini 3.1 Pro wins six of the seven areas where both have results: coding, reasoning, facts, math, long documents and following instructions. Step 3.5 Flash wins none, but costs 97% less. They are level on agents.
Which is better for coding?
Gemini 3.1 Pro. It wins 4 of the 4 coding tests both models report; Step 3.5 Flash wins none.
Which is cheaper?
Gemini 3.1 Pro costs $2.00 per million input tokens and $12.00 per million output tokens; Step 3.5 Flash costs $0.10 and $0.30. That makes Step 3.5 Flash about 97% cheaper for the same work.
How do you compare the two?
We use the 26 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 9 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.