Model comparison
Claude Opus 4.8 vs Step 5 Preview
Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 47.9 on the Noometry Index. Step 5 Preview costs 7.0× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.
Last verified . 18 shared benchmarks.
StepFunSummary
- They share 18 benchmarks with published results for both. Claude Opus 4.8 scores higher in 9 categories and Step 5 Preview in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 4.8 leads 78.4 to 46.1.
- The biggest single-benchmark swing is ProofBench: 69% for Claude Opus 4.8 and 42% for Step 5 Preview.
- Step 5 Preview is cheaper at $1 / $2.70 per million input/output tokens, against $5 / $25 for Claude Opus 4.8.
- Step 5 Preview accepts more context: 1.02M tokens versus 1M.
Side by side
| Claude Opus 4.8 | Step 5 Preview | |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 60.7 | 47.9 |
| Released | 2026-05-28 | 2026-09-16 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1.02M |
| Max output | 128K | 66K |
| Input $ / M tokens | $5 | $1 |
| Output $ / M tokens | $25 | $2.70 |
| Results tracked | 65 | 18 |
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Category by category
Coding Claude Opus 4.8 leads
Claude Opus 4.8: 59.9 (#12), Step 5 Preview: 51.8 (#36)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena WebDev | 1556 | 1564 |
| SciCode | 53.5% | 58.9% |
| LMArena Coding | 1490 | 1480 |
| DeepSWE | 59% | — |
| FrontierCode | 46.5% | — |
| GSO | 47.1% | — |
| WeirdML | 82.9% | — |
| ALE-Bench | 1,564 | — |
Agentic & Tool Use Not comparable
Claude Opus 4.8: 47.6 (#11), Step 5 Preview: —
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| APEX-Agents | 48.9% | — |
| OSWorld 2.0 | 20.6% | — |
| Remote Labor Index | 8.3% | — |
| τ²-bench Banking | 39.7% | — |
| DeepResearch Bench | 50.2% | — |
| PostTrainBench | 33.8% | — |
| GBAEval | 70.9% | — |
| GDP.pdf | 24% | — |
| LMArena Search | 1204 | — |
| Vending-Bench 2 | 5,787 | — |
Reasoning Claude Opus 4.8 leads
Claude Opus 4.8: 64.7 (#16), Step 5 Preview: 40.0 (#57)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| CritPt | 20.9% | 20.9% |
| LMArena Hard Prompts | 1482 | 1465 |
| ARC-AGI-2 | 72.1% | — |
| SimpleBench | 64.8% | — |
| Kagi LLM Benchmark | 88.8% | — |
| NYT Connections (extended) | 91.1% | — |
| ARC-AGI-1 | 92.5% | — |
| Chess Puzzles | 34% | — |
| EnigmaEval | 23.5% | — |
| EBR-Bench | 28.6% | — |
| Mystery Game Puzzles | 36% | — |
| DTBench | 94.9% | — |
| LMCA | 57.5% | — |
| Surface Evolver Bench | 87.5% | — |
| Bench to the Future 3 | 0.14 | — |
| Epoch Capabilities Index | 158.21 | — |
| ForecastBench | 59.9 | — |
Math Claude Opus 4.8 leads
Claude Opus 4.8: 78.4 (#13), Step 5 Preview: 46.1 (#72)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| ProofBench | 69% | 42% |
| LMArena Math | 1487 | 1470 |
| FrontierMath (Tiers 1-3) | 80% | — |
| FrontierMath Tier 4 | 56.1% | — |
| MathArena Final-Answer Competitions | 91.8% | — |
| OTIS Mock AIME 2024-2025 | 98.3% | — |
| FrontierMath (Feb 2025 set) | 47.2% | — |
| FrontierMath Tier 4 (v1) | 31.3% | — |
Knowledge Claude Opus 4.8 leads
Claude Opus 4.8: 61.3 (#29), Step 5 Preview: 41.2 (#112)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1502 | 1470 |
| GPQA Diamond | 91% | — |
| SimpleQA Verified | 53% | — |
Multimodal Claude Opus 4.8 leads
Claude Opus 4.8: 42.9 (#26), Step 5 Preview: 41.0 (#41)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Vision | 1294 | 1267 |
| Blueprint-Bench 2 | 14.5% | — |
| Furniture Assembly | 42.5% | — |
| LMArena Document | 1475 | — |
Multilingual Claude Opus 4.8 leads
Claude Opus 4.8: 55.2 (#33), Step 5 Preview: 53.8 (#54)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1450 | 1432 |
| LMArena Chinese | 1507 | 1519 |
| LMArena Russian | 1474 | 1436 |
| LMArena Spanish | 1466 | 1439 |
| LMArena French | 1481 | — |
| LMArena German | 1472 | — |
| LMArena Japanese | 1440 | — |
| LMArena Korean | 1432 | — |
Instruction Following Claude Opus 4.8 leads
Claude Opus 4.8: 77.4 (#24), Step 5 Preview: 76.0 (#50)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1476 | 1444 |
Long Context Too close to call
Claude Opus 4.8: 45.4 (#35), Step 5 Preview: 44.5 (#64)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1483 | 1455 |
Writing & Preference Claude Opus 4.8 leads
Claude Opus 4.8: 72.0 (#16), Step 5 Preview: 62.8 (#71)
| Benchmark | Claude Opus 4.8 | Step 5 Preview |
|---|---|---|
| LMArena Text | 1461 | 1442 |
| LMArena Creative Writing | 1454 | 1410 |
| LMArena Multi-Turn | 1476 | 1447 |
| EQ-Bench Creative Writing | 1840 | — |
| EQ-Bench 4 | 1281 | — |
Frequently asked questions
Is Claude Opus 4.8 better than Step 5 Preview?
Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 47.9 on the Noometry Index. Step 5 Preview costs 7.0× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 4.8 or Step 5 Preview?
Step 5 Preview is cheaper. It lists at $1 per million input tokens and $2.70 per million output tokens; Claude Opus 4.8 lists at $5 and $25.
Is Claude Opus 4.8 or Step 5 Preview better for coding?
Claude Opus 4.8 scores higher on coding benchmarks: 59.9 versus 51.8 in the Noometry coding category.
Which has the bigger context window?
Step 5 Preview does, with 1.02M tokens against 1M.
How many benchmarks do Claude Opus 4.8 and Step 5 Preview share?
18 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Step 5 Preview has 18.