Model comparison
Grok 4.3 vs Mercury 2.5
Grok 4.3 is the stronger model overall, scoring 43.8 to 33.5 on the Noometry Index. Mercury 2.5 costs 23× less per token, which makes it the better buy when Grok 4.3's lead doesn't matter for your workload.
Last verified . 4 shared benchmarks.
Summary
- They share 4 benchmarks with published results for both. Grok 4.3 scores higher in 3 categories and Mercury 2.5 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where Grok 4.3 leads 46.0 to 23.3.
- The biggest single-benchmark swing is SciCode: 47.3% for Grok 4.3 and 38.5% for Mercury 2.5.
- Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $1.25 / $2.50 for Grok 4.3.
- Grok 4.3 accepts more context: 1M tokens versus 260K.
Side by side
| Grok 4.3 | Mercury 2.5 | |
|---|---|---|
| Provider | xAI | Inception |
| Noometry Index | 43.8 | 33.5 |
| Released | 2026-04-17 | 2026-09-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 260K |
| Max output | 30K | 66K |
| Input $ / M tokens | $1.25 | $0.04 |
| Output $ / M tokens | $2.50 | $0.15 |
| Results tracked | 40 | 4 |
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Category by category
Coding Grok 4.3 leads
Grok 4.3: 41.6 (#121), Mercury 2.5: 39.5 (#156)
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| SciCode | 47.3% | 38.5% |
| ALE-Bench | 944.17 | 301.65 |
| LMArena WebDev | 1357 | — |
| WeirdML | 49.9% | — |
| LMArena Coding | 1415 | — |
Agentic & Tool Use Not comparable
Grok 4.3: 27.7 (#99), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| GDP.pdf | 8% | — |
| LMArena Search | 1165 | — |
| Vending-Bench 2 | 35.26 | — |
Reasoning Grok 4.3 leads
Grok 4.3: 35.9 (#68), Mercury 2.5: 22.4 (#193)
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| CritPt | 8% | 0% |
| NYT Connections (extended) | 55.2% | — |
| Chess Puzzles | 25% | — |
| LMArena Hard Prompts | 1396 | — |
| DTBench | 90.7% | — |
| LMCA | 38.3% | — |
| Epoch Capabilities Index | 149.16 | — |
| ForecastBench | 60.3 | — |
Math Grok 4.3 leads
Grok 4.3: 46.0 (#74), Mercury 2.5: 23.3 (#272)
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| ProofBench | 11% | 3% |
| FrontierMath (Tiers 1-3) | 42.8% | — |
| FrontierMath Tier 4 | 14.6% | — |
| OTIS Mock AIME 2024-2025 | 93.3% | — |
| LMArena Math | 1388 | — |
Knowledge Not comparable
Grok 4.3: 52.5 (#62), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| GPQA Diamond | 88.8% | — |
| SimpleQA Verified | 33.2% | — |
| LMArena Expert | 1385 | — |
Multimodal Not comparable
Grok 4.3: 31.6 (#104), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| LMArena Vision | 1229 | — |
| Blueprint-Bench 2 | 0% | — |
Multilingual Not comparable
Grok 4.3: 50.5 (#120), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| LMArena Non-English | 1385 | — |
| LMArena Chinese | 1422 | — |
| LMArena French | 1412 | — |
| LMArena German | 1395 | — |
| LMArena Japanese | 1379 | — |
| LMArena Korean | 1356 | — |
| LMArena Russian | 1399 | — |
| LMArena Spanish | 1398 | — |
Instruction Following Not comparable
Grok 4.3: 72.1 (#140), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| LMArena Instruction Following | 1366 | — |
Long Context Not comparable
Grok 4.3: 42.5 (#123), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| LMArena Longer Query | 1393 | — |
Writing & Preference Not comparable
Grok 4.3: 58.5 (#118), Mercury 2.5: —
| Benchmark | Grok 4.3 | Mercury 2.5 |
|---|---|---|
| LMArena Text | 1397 | — |
| LMArena Creative Writing | 1380 | — |
| EQ-Bench 4 | 1075 | — |
| LMArena Multi-Turn | 1406 | — |
Frequently asked questions
Is Grok 4.3 better than Mercury 2.5?
Grok 4.3 is the stronger model overall, scoring 43.8 to 33.5 on the Noometry Index. Mercury 2.5 costs 23× less per token, which makes it the better buy when Grok 4.3's lead doesn't matter for your workload.
Which is cheaper, Grok 4.3 or Mercury 2.5?
Mercury 2.5 is cheaper. It lists at $0.04 per million input tokens and $0.15 per million output tokens; Grok 4.3 lists at $1.25 and $2.50.
Is Grok 4.3 or Mercury 2.5 better for coding?
Grok 4.3 scores higher on coding benchmarks: 41.6 versus 39.5 in the Noometry coding category.
Which has the bigger context window?
Grok 4.3 does, with 1M tokens against 260K.
How many benchmarks do Grok 4.3 and Mercury 2.5 share?
4 benchmarks have published results for both models. Grok 4.3 has 40 scored results on Noometry and Mercury 2.5 has 4.