Model comparison
GPT-5.6 Terra vs Mercury
GPT-5.6 Terra is the stronger model overall, scoring 59.2 to 37.6 on the Noometry Index.
Last verified . 9 shared benchmarks.
Summary
- They share 9 benchmarks with published results for both. GPT-5.6 Terra scores higher in 6 categories and Mercury in 0 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.6 Terra leads 60.7 to 17.5.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 51.3% for GPT-5.6 Terra and 21.6% for Mercury.
Side by side
| GPT-5.6 Terra | Mercury | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 59.2 | 37.6 |
| Released | 2026-07-09 | — |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | — |
| Max output | 128K | — |
| Input $ / M tokens | $2 | — |
| Output $ / M tokens | $12 | — |
| Results tracked | 52 | 9 |
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Category by category
Coding GPT-5.6 Terra leads
GPT-5.6 Terra: 57.7 (#19), Mercury: 38.7 (#170)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Coding | 1484 | 1322 |
| DeepSWE | 69.6% | — |
| FrontierCode | 41.3% | — |
| CursorBench | 41.3% | — |
| LMArena WebDev | 1522 | — |
| SciCode | 55% | — |
| WeirdML | 78.3% | — |
| ALE-Bench | 1,951 | — |
Agentic & Tool Use Not comparable
GPT-5.6 Terra: 40.1 (#25), Mercury: —
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| APEX-Agents | 58.2% | — |
| BALROG | 53.2% | — |
| GDP.pdf | 24.7% | — |
| Vending-Bench 2 | 7,343 | — |
Reasoning GPT-5.6 Terra leads
GPT-5.6 Terra: 60.7 (#21), Mercury: 17.5 (#293)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| Kagi LLM Benchmark | 51.3% | 21.6% |
| LMArena Hard Prompts | 1468 | 1285 |
| ARC-AGI-2 | 83.9% | — |
| SimpleBench | 48.9% | — |
| NYT Connections (extended) | 78.4% | — |
| ARC-AGI-1 | 96.5% | — |
| CritPt | 30% | — |
| Chess Puzzles | 54% | — |
| Mystery Game Puzzles | 35% | — |
| DTBench | 93.3% | — |
| LMCA | 55% | — |
| Surface Evolver Bench | 83.8% | — |
| Epoch Capabilities Index | 159.62 | — |
Math Not comparable
GPT-5.6 Terra: 81.6 (#12), Mercury: —
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| FrontierMath (Tiers 1-3) | 86% | — |
| FrontierMath Tier 4 | 70.7% | — |
| OTIS Mock AIME 2024-2025 | 99.7% | — |
| ProofBench | 74% | — |
| LMArena Math | 1466 | — |
Knowledge Not comparable
GPT-5.6 Terra: 61.2 (#30), Mercury: —
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| GPQA Diamond | 93.3% | — |
| SimpleQA Verified | 43.2% | — |
| LMArena Expert | 1492 | — |
Multimodal Not comparable
GPT-5.6 Terra: 47.3 (#11), Mercury: —
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Vision | 1271 | — |
| Blueprint-Bench 2 | 30.8% | — |
| Furniture Assembly | 54.2% | — |
| LMArena Document | 1472 | — |
Multilingual GPT-5.6 Terra leads
GPT-5.6 Terra: 54.4 (#44), Mercury: 41.6 (#206)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Non-English | 1439 | 1260 |
| LMArena Chinese | 1513 | — |
| LMArena French | 1471 | — |
| LMArena German | 1460 | — |
| LMArena Japanese | 1457 | — |
| LMArena Korean | 1425 | — |
| LMArena Russian | 1450 | — |
| LMArena Spanish | 1448 | — |
Instruction Following GPT-5.6 Terra leads
GPT-5.6 Terra: 76.4 (#40), Mercury: 65.2 (#224)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Instruction Following | 1454 | 1239 |
Long Context GPT-5.6 Terra leads
GPT-5.6 Terra: 44.4 (#68), Mercury: 38.4 (#198)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Longer Query | 1451 | 1266 |
Writing & Preference GPT-5.6 Terra leads
GPT-5.6 Terra: 70.2 (#23), Mercury: 46.2 (#221)
| Benchmark | GPT-5.6 Terra | Mercury |
|---|---|---|
| LMArena Text | 1447 | 1282 |
| LMArena Creative Writing | 1410 | 1191 |
| LMArena Multi-Turn | 1449 | 1282 |
| EQ-Bench Creative Writing | 1855 | — |
| EQ-Bench 4 | 1234 | — |
Frequently asked questions
Is GPT-5.6 Terra better than Mercury?
GPT-5.6 Terra is the stronger model overall, scoring 59.2 to 37.6 on the Noometry Index.
Is GPT-5.6 Terra or Mercury better for coding?
GPT-5.6 Terra scores higher on coding benchmarks: 57.7 versus 38.7 in the Noometry coding category.
How many benchmarks do GPT-5.6 Terra and Mercury share?
9 benchmarks have published results for both models. GPT-5.6 Terra has 52 scored results on Noometry and Mercury has 9.