Claude Fable 5 vs Grok 4.20
Wins 7 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Long documents
Wins 1 of 8 areas
Following instructions
Claude Fable 5 is the stronger all-rounder.Grok 4.20 is cheaper and better at following instructions.
Scores updated · 23 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 thinking40Claude Fable 54 of 4 tests
- CodingWriting and fixing software20Claude Fable 52 of 2 tests
- AgentsCarrying out multi-step tasks on its own20Claude Fable 52 of 2 tests
- MathCompetition and research-level math20Claude Fable 52 of 2 tests
- FactsGetting facts right instead of making them up21Claude Fable 52 of 3 tests
- Images and chartsUnderstanding pictures, charts and video10Claude Fable 51 of 1 test
- Long documentsFinding answers in very long texts10Claude Fable 51 of 1 test
- Following instructionsDoing exactly what it is asked01Grok 4.201 of 1 test
Images and charts, 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.
Grok 4.20 costs 94% 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 Claude Fable 5 pulls ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+73.1points ahead
- Unpublished advanced math problemsFrontierMath Tiers 1-3 (v2)+42.1points ahead
- Short factual questions, answered correctlySimpleQA Verified+40.5points ahead
Where Grok 4.20 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+41.2points ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+19.4points ahead
Every test, side by side
All 23 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Fable 5
- Terminal-Bench HardClaude Fable 5 by 2262.940.9+22
- SciCodeClaude Fable 5 by 16.36144.7+16.3
AgentsClaude Fable 5
- AA ApexAgentsClaude Fable 5 by 29.143.314.2+29.1
- GDPValClaude Fable 5 by 28.655.627+28.6
ReasoningClaude Fable 5
- ARC-AGI-2Claude Fable 5 by 24.189.265.1+24.1
- Humanity's Last ExamClaude Fable 5 by 23.155.532.4+23.1
- CritPtClaude Fable 5 by 22.628.66+22.6
- GPQA DiamondClaude Fable 5 by 4.192.688.5+4.1
FactsClaude Fable 5
- AA-Omniscience · Non-hallucinationGrok 4.20 by 41.236.477.6+41.2
- SimpleQA VerifiedClaude Fable 5 by 40.570.730.2+40.5
- AA-Omniscience · AccuracyClaude Fable 5 by 36.565.328.9+36.5
Images and chartsClaude Fable 5
- MMMU-ProClaude Fable 5 by 1184.273.2+11
MathClaude Fable 5
- FrontierMath Tier 4Claude Fable 5 by 73.190.217.1+73.1
- FrontierMath Tiers 1-3 (v2)Claude Fable 5 by 42.18744.9+42.1
Following instructionsGrok 4.20
- IFBenchGrok 4.20 by 19.463.582.9+19.4
Other results7 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.
- HiL-Bench (Tools-allowed)Claude Fable 5 by 36.356.320+36.3
- Artificial Analysis Coding IndexClaude Fable 5 by 34.376.542.2+34.3
- AA-OmniscienceClaude Fable 5 by 30.343.312.9+30.3
- AA IntelligenceClaude Fable 5 by 24.449.625.2+24.4
- ARC-AGI-1Claude Fable 5 by 998.589.5+9
- τ²-Bench Telecom (AA run)Claude Fable 5 by 298.596.5+2
- AA Agentic Indextie5150.9tie
Questions people ask
Which is better, Claude Fable 5 or Grok 4.20?
Claude Fable 5 wins seven of the eight areas we test: coding, agents, reasoning, facts, images and charts, math and long documents. Grok 4.20 wins following instructions, and costs 94% less.
Which is better for coding?
Claude Fable 5. It wins 2 of the 2 coding tests both models report; Grok 4.20 wins none.
Which is cheaper?
Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Grok 4.20 costs $1.25 and $2.50. That makes Grok 4.20 about 94% cheaper for the same work.
How do you compare the two?
We use the 23 benchmark tests both models have published scores on. The verdict counts the 16 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 7 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.