Coding
Directional only- Grok 4.20
- 67.1
- Grok Code Fast 1
- 70.8
- Weighted basis
- 2 vs 1 rows
- Reading
- Directional only
Model comparison
Grok 4.20 vs Grok Code Fast 1
Updated July 28, 2026. Public scores include evidence status and uncertainty. They are not guarantees for a specific workload.
Grok 4.20 has the higher public score estimate, 53.88 versus 37.75, but the 90% score intervals overlap. Treat that as a lead, not a settled winner.
1 results are shared. Category rows based on different benchmark sets are marked directional and do not name a winner.
Which one for your work
Recommendations appear only when a shared evidence basis or an explicit operating constraint supports the call. Secondary and unsupported use cases stay disclosed below the initial list.
Long documents
Prompts that approach the documented context limit
Grok 4.20
Grok 4.20 has the larger documented context window.
Confidence: documented
Chat turn cost
1K fresh input + 500 output tokens
Grok Code Fast 1
Grok Code Fast 1 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.
Confidence: listed-rates
Cache-heavy agent loop cost
200K cached + 20K fresh input + 10K output tokens
Grok Code Fast 1
Grok Code Fast 1 has the lower estimated token cost for this stated workload. Grok 4.20 has no published cached-input rate, so cached tokens use its listed input rate. Grok Code Fast 1 has no published cached-input rate, so cached tokens use its listed input rate.
Confidence: rate-fallback
Show secondary and unsupported calls
Repository review cost
50K fresh input + 3K output tokens
Grok Code Fast 1
Grok Code Fast 1 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.
Confidence: listed-rates
Coding work
Code generation, repair, and software-engineering tasks
Not enough matched evidence
The category averages use different weighted benchmark sets, so they are directional rather than like-for-like.
Confidence: limited
Agentic work
Tool use, computer use, and multi-step task completion
Not enough matched evidence
No shared weighted benchmark basis supports a winner.
Confidence: limited
What is actually comparable
Shared results can support a head-to-head reading. Results present for only one model describe coverage, not superiority.
17 Grok 4.20 only
1 Shared
- Shared results
- 1
- Grok 4.20 only
- 17
- Grok Code Fast 1 only
- 0
- Like-for-like categories
- 0 / 8
1 category uses different evidence sets. Those rows remain visible for coverage context but do not name a winner.
Category results, on a stated basis
Each row states whether both averages use the same weighted benchmark set. Directional and not-comparable rows remain visible, but they never receive a winner in this template.
Agentic
Not comparable- Grok 4.20
- 47.1
- Grok Code Fast 1
- Not measured
- Weighted basis
- 1 vs 0 rows
- Reading
- Not comparable
Reasoning
Not comparable- Grok 4.20
- 53.3
- Grok Code Fast 1
- Not measured
- Weighted basis
- 1 vs 0 rows
- Reading
- Not comparable
Knowledge
Not comparable- Grok 4.20
- Not measured
- Grok Code Fast 1
- Not measured
- Weighted basis
- 0 vs 0 rows
- Reading
- Not comparable
Math
Not comparable- Grok 4.20
- Not measured
- Grok Code Fast 1
- Not measured
- Weighted basis
- 0 vs 0 rows
- Reading
- Not comparable
Multilingual
Not comparable- Grok 4.20
- Not measured
- Grok Code Fast 1
- Not measured
- Weighted basis
- 0 vs 0 rows
- Reading
- Not comparable
Multimodal
Not comparable- Grok 4.20
- 70.1
- Grok Code Fast 1
- Not measured
- Weighted basis
- 2 vs 0 rows
- Reading
- Not comparable
Instruction following
Not comparable- Grok 4.20
- Not measured
- Grok Code Fast 1
- Not measured
- Weighted basis
- 0 vs 0 rows
- Reading
- Not comparable
| Category | Grok 4.20 | Grok Code Fast 1 | Weighted basis | Reading |
|---|---|---|---|---|
| Coding | 67.1 | 70.8 | Directional only2 vs 1 rows | Directional only |
| Agentic | 47.1 | Not measured | Not comparable1 vs 0 rows | Not comparable |
| Reasoning | 53.3 | Not measured | Not comparable1 vs 0 rows | Not comparable |
| Knowledge | Not measured | Not measured | Not comparable0 vs 0 rows | Not comparable |
| Math | Not measured | Not measured | Not comparable0 vs 0 rows | Not comparable |
| Multilingual | Not measured | Not measured | Not comparable0 vs 0 rows | Not comparable |
| Multimodal | 70.1 | Not measured | Not comparable2 vs 0 rows | Not comparable |
| Instruction following | Not measured | Not measured | Not comparable0 vs 0 rows | Not comparable |
Shape of the matched evidence
Only shared public evidence is shown. Sparse evidence stays a ruled list rather than being closed into a radar shape.
Too few matched category axes support a radar. The ruled list below shows only shared benchmark results; positions use each benchmark’s normalized display scale when available.
SWE-bench Verified
Coding
What each workload costs
Three fixed token mixes turn per-token rates into comparable decisions. Each scenario states context fit and whether cached input had to fall back to the published list-input rate.
Chat turn
1K fresh input + 500 output tokens
- Grok 4.20
- $0.005
- Fits in one request
- Grok Code Fast 1
- $0.00095
- Fits in one request
Grok Code Fast 1 has the lower modeled cost
Costs use the listed standard API rates.
Repository review
50K fresh input + 3K output tokens
- Grok 4.20
- $0.118
- Fits in one request
- Grok Code Fast 1
- $0.0145
- Fits in one request
Grok Code Fast 1 has the lower modeled cost
Costs use the listed standard API rates.
Cache-heavy agent loop
200K cached + 20K fresh input + 10K output tokens
- Grok 4.20
- $0.5
- Fits in one request
- Cached input priced at the published list-input rate
- Grok Code Fast 1
- $0.059
- Fits in one request
- Cached input priced at the published list-input rate
Grok Code Fast 1 has the lower modeled cost
Grok 4.20 has no published cached-input rate, so cached tokens use its listed input rate. Grok Code Fast 1 has no published cached-input rate, so cached tokens use its listed input rate.
Specification differences
Sourced differences are shown directly. Missing facts stay explicit instead of being inferred from a model name or family.
SpecificationGrok 4.20Grok Code Fast 1
Context window
Maximum documented context; output-token limits may be lower.
Grok 4.20
2M
Grok Code Fast 1
256K
API model ID
Grok 4.20
Not sourced
Grok Code Fast 1
Not sourced
Cached-input rate
A missing cached-input rate falls back to the listed input rate only in the stated workload estimate.
Grok 4.20
Not published
Grok Code Fast 1
Not published
Documented inputs
Grok 4.20
Not sourced
Grok Code Fast 1
Not sourced
Documented outputs
Grok 4.20
Not sourced
Grok Code Fast 1
Not sourced
Provider availability
Grok 4.20
Not sourced
Grok Code Fast 1
Not sourced
Reasoning profile
Grok 4.20
Reasoning
Grok Code Fast 1
Non-Reasoning
Weight access
Grok 4.20
Proprietary
Grok Code Fast 1
Proprietary
License
Grok 4.20
Proprietary
Grok Code Fast 1
Proprietary
Release date
Grok 4.20
2026-03-10
Grok Code Fast 1
2025-08-28
If you already use one of these models
- Deployment change
- Both entries list xAI as the provider. Confirm endpoint, model ID, limits, and feature support before switching.
- Quality signal
- Grok 4.20 has the higher public score estimate, 53.88 versus 37.75, but the 90% score intervals overlap.
- Workload cost
- Repository review: $0.118 vs $0.0145. Cache-heavy agent loop: $0.5 vs $0.059.
- Context tradeoff
- Grok 4.20 has the larger documented window (2M).
Run the same representative tasks against both endpoints before changing production traffic.
Benchmark evidence
The full public result ledger is available for audit without forcing a wide desktop table onto a phone.
Browse raw public benchmark evidence18 rows
Agentic
Coding
LiveCodeBench Pro
Grok 4.2074.2%SourceGrok Code Fast 1—Not directly comparable
SWE-bench Verified
Grok 4.2076.7%SourceGrok Code Fast 170.8%SourceGrok 4.20 leads this result
SWE-bench Pro
Grok 4.2051.8%SourceGrok Code Fast 1—Not directly comparable
Vibe Code Bench
Grok 4.204.06%SourceGrok Code Fast 1—Not directly comparable
Reasoning
Knowledge
Multimodal
MMMU-Pro
Grok 4.2075.2%SourceGrok Code Fast 1—Not directly comparable
CharXiv
Grok 4.2060.9%SourceGrok Code Fast 1—Not directly comparable
ERQA
Grok 4.2054.1%SourceGrok Code Fast 1—Not directly comparable
SimpleVQA
Grok 4.2057.4%SourceGrok Code Fast 1—Not directly comparable
MedXpertQA (MM)
Grok 4.2065.8%SourceGrok Code Fast 1—Not directly comparable
Frequently asked questions
Which is better, Grok 4.20 or Grok Code Fast 1?
Grok 4.20 has the higher public score estimate, 53.88 versus 37.75, but the 90% score intervals overlap. The higher estimate is not a decisive winner because the uncertainty ranges overlap.
Which is better for coding, Grok 4.20 or Grok Code Fast 1?
The current coding averages use different weighted benchmark sets, so BenchLM does not name a winner from them. Read the shared benchmark rows directly and test the models on the same task set.
Which is better for agentic tasks, Grok 4.20 or Grok Code Fast 1?
The published evidence does not provide a shared weighted agentic tasks basis for both models, so BenchLM does not name a agentic tasks winner.
Which costs less, Grok 4.20 or Grok Code Fast 1?
For the stated presets, chat costs $0.005 on Grok 4.20 and $0.00095 on Grok Code Fast 1; repository review costs $0.118 and $0.0145; the cache-heavy agent loop costs $0.5 and $0.059. Grok 4.20 has no published cached-input rate, so cached tokens use its listed input rate. Grok Code Fast 1 has no published cached-input rate, so cached tokens use its listed input rate.
Which has the larger context window, Grok 4.20 or Grok Code Fast 1?
Grok 4.20 has the larger documented context window: 2M, compared with 256K.
Related comparisons
Last updated July 28, 2026
Keep the decision current
One weekly note on benchmark changes, pricing moves, and models worth re-testing.