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BenchLM

Model comparison

Claude Opus 4.8 vs Grok 4.20

Data verified

Head-to-head evidence from 9 shared benchmark results across 4 categories. Overall scores shown here use BenchLM's provisional ranking lane.

85/100
Margin
17.0pts
← winning
68/100
3 category wins0 category wins

Verified leaderboard positions: Claude Opus 4.8 #3; Grok 4.20 unranked

Evidence parity. Claude Opus 4.8 and Grok 4.20 share 9 comparable benchmark results. 3 of 8 categories are comparable. 44 results are unique to Claude Opus 4.8; 10 to Grok 4.20.

Updated July 12, 2026
Shared results
9
Claude Opus 4.8 only
44
Grok 4.20 only
10
Comparable categories
3 / 8

Pick Claude Opus 4.8 if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if you want the cheaper token bill or you need the larger 2M context window.

Confidence note. This is a partial-evidence comparison with 9 shared benchmark results across 4 evidence categories; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Claude Opus 4.8 is clearly ahead on the provisional aggregate, 85 to 68. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Opus 4.8's sharpest advantage is in agentic, where it averages 80.3 against 47.1. The single biggest benchmark swing on the page is CharXiv, 89.9% to 60.9%.

Claude Opus 4.8 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. That is roughly 4.2x on output cost alone. Grok 4.20 gives you the larger context window at 2M, compared with 1M for Claude Opus 4.8.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for Claude Opus 4.8 and Grok 4.20
CategoryClaude Opus 4.8ΔGrok 4.20
AgenticClaude Opus 4.880.3Margin← 33.2Grok 4.2047.1
CodingClaude Opus 4.876.4Margin← 15.3Grok 4.2061.1
MultimodalClaude Opus 4.877.0Margin← 6.9Grok 4.2070.1
ReasoningClaude Opus 4.8Not measuredMarginNo overlapGrok 4.2053.3
KnowledgeClaude Opus 4.862.7MarginNo overlapGrok 4.20Not measured
MathClaude Opus 4.853.9MarginNo overlapGrok 4.20Not measured

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · Claude Opus 4.8B · Grok 4.20

  1. CharXiv

    Multimodal
    Source ↗
    A 89.9%B 60.9%
    Winner: Claude Opus 4.8Δ 29
    CharXiv: Claude Opus 4.8 scored 89.9%; Grok 4.20 scored 60.9%. Claude Opus 4.8 wins this benchmark.

  2. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 74.6%B 47.1%
    Winner: Claude Opus 4.8Δ 27.5
    Terminal-Bench 2.0: Claude Opus 4.8 scored 74.6%; Grok 4.20 scored 47.1%. Claude Opus 4.8 wins this benchmark.

  3. SWE-bench Pro

    Coding
    Source ↗
    A 69.2%B 51.8%
    Winner: Claude Opus 4.8Δ 17.4
    SWE-bench Pro: Claude Opus 4.8 scored 69.2%; Grok 4.20 scored 51.8%. Claude Opus 4.8 wins this benchmark.

  4. SWE-bench Verified

    Coding
    Source ↗
    A 88.6%B 76.7%
    Winner: Claude Opus 4.8Δ 11.9
    SWE-bench Verified: Claude Opus 4.8 scored 88.6%; Grok 4.20 scored 76.7%. Claude Opus 4.8 wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricClaude Opus 4.8Grok 4.20Comparison
Input / output priceUSD per 1M tokensClaude Opus 4.8$5 input / $25 outputGrok 4.20$2 input / $6 outputGrok 4.20 has the lower combined listed price.
Generation speedtokens per secondClaude Opus 4.8Not availableGrok 4.20233 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Opus 4.8Not availableGrok 4.2010.33 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Opus 4.81MGrok 4.202MGrok 4.20 lists the larger context window.

Benchmark Deep Dive

AgenticClaude Opus 4.8 wins
BenchmarkClaude Opus 4.8Grok 4.20Result
Terminal-Bench 2.0Source 74.6%47.1%Claude Opus 4.8 leads
BrowseCompSource 84.3%—Not comparable
DeepSearchQASource 93.1%62.8%Claude Opus 4.8 leads
OSWorld-VerifiedSource 83.4%—Not comparable
Finance Agent v2Source 53.9%—Not comparable
GDPval-AASource 1600—Not comparable
MCP AtlasSource 82.2%—Not comparable
ToolathlonSource 59.9%—Not comparable
Gert LabsSource 72.97%38.36%Claude Opus 4.8 leads
AA Agentic IndexSource 47.2%—Not comparable
Tau2-TelecomSource 94.4%—Not comparable
GDPval-AASource 55.0%—Not comparable
ResearchClawBenchSource 21.1%—Not comparable
OSWorld 2.0Source 20.6%—Not comparable
AA BriefcaseSource 1354—Not comparable
AA AutomationBenchSource 48.5%—Not comparable
AA EnterpriseOps-GymSource 44.0%—Not comparable
AA Harvey LABSource 7.5%—Not comparable
AA Tau3 BankingSource 27.6%—Not comparable
CodingClaude Opus 4.8 wins
BenchmarkClaude Opus 4.8Grok 4.20Result
SWE-bench VerifiedSource 88.6%76.7%Claude Opus 4.8 leads
SWE-bench ProSource 69.2%51.8%Claude Opus 4.8 leads
SWE MultilingualSource 84.4%—Not comparable
SWE MultimodalSource 38.4%—Not comparable
Terminal-Bench 2.0Source 74.6%—Not comparable
cursorBench31Source 58.4%—Not comparable
cursorBench32Source 62.3%—Not comparable
AA Coding IndexSource 74.3%—Not comparable
Terminal-Bench HardSource 58.3%—Not comparable
AA-SciCodeSource 53.5%—Not comparable
FrontierCodeSource 46.5%—Not comparable
AA Terminal-Bench 2.1Source 84.6%—Not comparable
LiveCodeBench ProSource —74.2%Not comparable
Vibe Code BenchSource —4.06%Not comparable
Reasoning
BenchmarkClaude Opus 4.8Grok 4.20Result
AA-LCRSource 67.7%—Not comparable
CritPtSource 20.9%—Not comparable
ARC-AGI-2Source —53.3%Not comparable
Knowledge
BenchmarkClaude Opus 4.8Grok 4.20Result
GPQASource 93.6%—Not comparable
GPQA-DSource 93.6%88.5%Claude Opus 4.8 leads
HLESource 57.9%—Not comparable
HLE w/o toolsSource 49.8%31.6%Claude Opus 4.8 leads
Artificial Analysis Intelligence IndexSource 55.7%—Not comparable
AA-GPQA DiamondSource 92.0%—Not comparable
AA-HLESource 45.7%—Not comparable
AA-Omniscience IndexSource 27.4%—Not comparable
AA-Omniscience AccuracySource 46.6%—Not comparable
AA-Omniscience Hallucination RateSource 35.9%—Not comparable
HealthBench HardSource —20.3%Not comparable
MedXpertQA (Text)Source —50.2%Not comparable
Math
BenchmarkClaude Opus 4.8Grok 4.20Result
USAMO 2026Source 96.7%—Not comparable
FrontierMath v2 (Tiers 1-3)Source 47.241%—Not comparable
FrontierMath v2 (Tier 4)Source 31.250%—Not comparable
Multilingual
BenchmarkClaude Opus 4.8Grok 4.20Result
INCLUDESource 87.6%—Not comparable
MultimodalClaude Opus 4.8 wins
BenchmarkClaude Opus 4.8Grok 4.20Result
OfficeQA ProSource 66.2%—Not comparable
ScreenSpot ProSource 87.9%—Not comparable
CharXivSource 89.9%60.9%Claude Opus 4.8 leads
CharXiv w/o toolsSource 80.5%—Not comparable
Design Arena WebsiteSource 12811271Claude Opus 4.8 leads
MMMU-ProSource —75.2%Not comparable
ERQASource —54.1%Not comparable
SimpleVQASource —57.4%Not comparable
MedXpertQA (MM)Source —65.8%Not comparable
GDPval-AASource —1055Not comparable
Inst. Following
BenchmarkClaude Opus 4.8Grok 4.20Result
AA-IFBenchSource 62.2%—Not comparable
Frequently Asked Questions (4)

Which is better, Claude Opus 4.8 or Grok 4.20?

Claude Opus 4.8 is ahead on BenchLM's provisional leaderboard, 85 to 68. The biggest single separator in this matchup is CharXiv, where the scores are 89.9% and 60.9%.

Which is better for coding, Claude Opus 4.8 or Grok 4.20?

Claude Opus 4.8 has the edge for coding in this comparison, averaging 76.4 versus 61.1. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Opus 4.8 or Grok 4.20?

Claude Opus 4.8 has the edge for agentic tasks in this comparison, averaging 80.3 versus 47.1. Inside this category, Gert Labs is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Opus 4.8 or Grok 4.20?

Claude Opus 4.8 has the edge for multimodal and grounded tasks in this comparison, averaging 77 versus 70.1. Inside this category, CharXiv is the benchmark that creates the most daylight between them.

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