GPT-5.6 Luna vs GPT-6 Astra
Wins 1 of 8 areas
Long documents
Wins 7 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Following instructions
GPT-6 Astra is the stronger all-rounder.GPT-5.6 Luna is cheaper and better at long documents.
Scores updated · 43 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.
- ReasoningHard problems that need careful thinking07GPT-6 Astra7 of 7 tests
- AgentsCarrying out multi-step tasks on its own05GPT-6 Astra5 of 5 tests
- CodingWriting and fixing software14GPT-6 Astra4 of 5 tests
- FactsGetting facts right instead of making them up03GPT-6 Astra3 of 3 tests
- MathCompetition and research-level math03GPT-6 Astra3 of 3 tests
- Images and chartsUnderstanding pictures, charts and video02GPT-6 Astra2 of 2 tests
- Following instructionsDoing exactly what it is asked01GPT-6 Astra1 of 1 test
- Long documentsFinding answers in very long texts10GPT-5.6 Luna1 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.
GPT-5.6 Luna costs 98% 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-6 Astra pulls ahead
- Solves new puzzle games it has never seenARC-AGI-3+99.7points ahead
- Complex command-line tasks across many fieldsTerminal-Bench 4.0+47.5points ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+41.3points ahead
Where GPT-5.6 Luna pulls ahead
- Reasons across sets of long documentsAA-LCR+3points ahead
- Programming problems, refreshed regularlyLiveBench · Coding+2.5points ahead
Every test, side by side
All 43 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-6 Astra
- LMArena · WebDevGPT-6 Astra by 257 rating points15191776+257 rating
- LiveBench · Agentic CodingGPT-6 Astra by 8.948.457.3+8.9
- Terminal-Bench 2.1GPT-6 Astra by 7.580.988.4+7.5
- SciCodeGPT-6 Astra by 2.953.656.5+2.9
- LiveBench · CodingGPT-5.6 Luna by 2.582.980.4+2.5
AgentsGPT-6 Astra
- Terminal-Bench 4.0GPT-6 Astra by 47.511.659.1+47.5
- τ-Bench V3 · BankingGPT-6 Astra by 10.331.141.4+10.3
- AA IT-Bench SREGPT-6 Astra by 8.340.348.6+8.3
- BrowseCompGPT-6 Astra by 8.283.391.5+8.2
- GDPValGPT-6 Astra by 5.64853.6+5.6
ReasoningGPT-6 Astra
- ARC-AGI-3GPT-6 Astra by 99.70.299.9+99.7
- SimpleBenchGPT-6 Astra by 36.846.883.6+36.8
- ARC-AGI-2GPT-6 Astra by 35.459.695+35.4
- Humanity's Last ExamGPT-6 Astra by 15.239.554.7+15.2
- CritPtGPT-6 Astra by 11.120.631.7+11.1
- LiveBench · ReasoningGPT-6 Astra by 7.185.692.7+7.1
- GPQA DiamondGPT-6 Astra by 591.196.1+5
FactsGPT-6 Astra
- AA-Omniscience · Non-hallucinationGPT-6 Astra by 41.37.448.7+41.3
- SimpleQA VerifiedGPT-6 Astra by 34.64175.6+34.6
- AA-Omniscience · AccuracyGPT-6 Astra by 19.942.762.6+19.9
Images and chartsGPT-6 Astra
- MMMU-ProGPT-6 Astra by 8.378.686.9+8.3
- LMArena · VisionGPT-6 Astra by 23 rating points12581281+23 rating
MathGPT-6 Astra
- FrontierMath Tier 4GPT-6 Astra by 39.158.597.6+39.1
- FrontierMath Tiers 1-3 (v2)GPT-6 Astra by 11.682.193.7+11.6
- LiveBench · MathematicsGPT-6 Astra by 9.687.296.8+9.6
Following instructionsGPT-6 Astra
- LiveBench · Instruction FollowingGPT-6 Astra by 15.560.175.6+15.5
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.
- AA-OmniscienceGPT-6 Astra by 53.7-10.343.4+53.7
- Terminal-Bench 4.0GPT-6 Astra by 40.417.357.7+40.4
- OSWorld 2.0GPT-6 Astra by 2745.672.6+27
- livebench_languageGPT-6 Astra by 16.872.689.4+16.8
- AA IntelligenceGPT-6 Astra by 15.437.352.7+15.4
- Agents' Last ExamGPT-6 Astra by 950.359.3+9
- HealthBench Professional length-adjustedGPT-6 Astra by 955.764.7+9
- AA Agentic IndexGPT-6 Astra by 8.842.751.5+8.8
- HealthBench ProfessionalGPT-6 Astra by 7.755.763.4+7.7
- DeepSWE 1.1GPT-6 Astra by 7.16774.1+7.1
- ARC-AGI-1GPT-6 Astra by 6.890.797.5+6.8
- Artificial Analysis Coding IndexGPT-6 Astra by 5.571.476.9+5.5
- livebench_data_analysisGPT-6 Astra by 57883+5
- HealthBench Hard length-adjustedGPT-6 Astra by 4.63236.6+4.6
- HealthBench length-adjustedGPT-6 Astra by 2.555.858.3+2.5
- HealthBench Consensus length-adjustedtie95.195.5tie
Questions people ask
Which is better, GPT-5.6 Luna or GPT-6 Astra?
GPT-6 Astra wins seven of the eight areas we test: coding, agents, reasoning, facts, images and charts, math and following instructions. GPT-5.6 Luna wins long documents, and costs 98% less.
Which is better for coding?
GPT-6 Astra. It wins 4 of the 5 coding tests both models report; GPT-5.6 Luna wins 1.
Which is cheaper?
GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens; GPT-6 Astra costs $10.00 and $50.00. That makes GPT-5.6 Luna about 98% cheaper for the same work.
How do you compare the two?
We use the 43 benchmark tests both models have published scores on. The verdict counts the 27 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.