Pick Claude Opus 4.8 for agentic coding and multi-file debugging or long autonomous tasks. Pick Grok Code Fast 1 for fast, cheap agentic coding at $0.20/$1.50 or low-latency code generation and terminal tasks. On a tight budget at scale, Grok Code Fast 1 is the value pick.
Claude Opus 4.8 (Anthropic) and Grok Code Fast 1 (xAI) are two of the models people most often weigh against each other in 2026. Claude Opus 4.8 is the agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch. Grok Code Fast 1 is xAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: Grok Code Fast 1 is about 25× cheaper on input ($0.2/$1.5 per 1M tokens vs $5/$25 per 1M tokens) — a large enough gap that at scale it can be the single biggest line item in the decision.
Context window: Claude Opus 4.8 holds 3.9× more — 1M (~1,500 pages) vs 256K (~384 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: Claude Opus 4.8 is the newer model by about 9 months (released May 28, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Opus 4.8
Grok Code Fast 1
Provider
Anthropic (US)
xAI (US)
Released
May 28, 2026
August 28, 2025
Context window
1M (~1,500 pages)
256K (~384 pages)
Price (in/out)
$5/$25 per 1M tokens
$0.2/$1.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, code
SWE-Bench Verified
88.6%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic coding and multi-file debugging: Claude Opus 4.8 — Grok Code Fast 1 is comparatively weak here — a speed-tier coding model, not a frontier reasoner
Long autonomous tasks: Claude Opus 4.8 — Its 1M window holds about 3.9× more than Grok Code Fast 1's 256K in a single prompt.
Honest uncertainty flagging: Claude Opus 4.8 — The agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch — and it carries the larger 1M context.
Fast, cheap agentic coding at $0.20/$1.50: Grok Code Fast 1 — At $0.2/$1.5 per 1M tokens it undercuts Claude Opus 4.8 ($5/$25 per 1M tokens), and that gap compounds at volume.
Low-latency code generation and terminal tasks: Grok Code Fast 1 — XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality — and it runs cheaper at $0.2/$1.5 per 1M tokens.
High-volume coding pipelines where speed beats peak quality: Grok Code Fast 1 — Claude Opus 4.8 is comparatively weak here — not the cheapest for high-volume work
Lowest cost at scale: Grok Code Fast 1 — At $0.2/$1.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: Claude Opus 4.8 — Its 1M window is about 3.9× larger than Grok Code Fast 1's 256K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Grok Code Fast 1 — At $0.2/$1.5 per 1M tokens it undercuts Claude Opus 4.8, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Claude Opus 4.8 — Larger 1M window fits more in one prompt.
Anyone whose priority is agentic coding and multi-file debugging: Claude Opus 4.8 — It is specifically built for that.
Anyone whose priority is fast, cheap agentic coding at $0.20/$1.50: Grok Code Fast 1 — That is its strongest area.
Claude Opus 4.8: where it fits
The agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch. Released May 28, 2026 by Anthropic, it is built for agentic coding and multi-file debugging, long autonomous tasks, honest uncertainty flagging, and professional writing and reasoning.
Its trade-offs are real: highest per-token price of the frontier tier, and not the cheapest for high-volume work. At $5 in / $25 out per million tokens, it sits in the premium price band.
Grok Code Fast 1: where it fits
XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. Released August 28, 2025 by xAI, it is built for fast, cheap agentic coding at $0.20/$1.50, low-latency code generation and terminal tasks, high-volume coding pipelines where speed beats peak quality, and a 256K window sized for real codebases.
Its trade-offs: text and code only — no image, audio or video input, xAI did not publish a SWE-Bench Verified score, a speed-tier coding model, not a frontier reasoner, and narrow focus — built for code, not general knowledge work. At $0.2 in / $1.5 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Claude Opus 4.8 and Grok Code Fast 1 overlap enough that the right pick depends on your specific job. Grok Code Fast 1 costs less per token; Claude Opus 4.8 holds the larger context; and each leads in its own area — Claude Opus 4.8 for agentic coding and multi-file debugging, Grok Code Fast 1 for fast, cheap agentic coding at $0.20/$1.50. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Opus 4.8 or Grok Code Fast 1 better for coding?
Public SWE-Bench figures are not available for Grok Code Fast 1, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 4.8 leans toward agentic coding and multi-file debugging while Grok Code Fast 1 leans toward fast, cheap agentic coding at $0.20/$1.50, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 4.8 or Grok Code Fast 1?
Grok Code Fast 1 is cheaper — $5/$25 per 1M tokens vs $0.2/$1.5 per 1M tokens, roughly 25× apart on input.
Which has the bigger context window?
Claude Opus 4.8 — 1M vs 256K, about 3.9× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Opus 4.8 and Grok Code Fast 1 together?
Yes — a multi-model platform like LumiChats gives you Claude Opus 4.8, Grok Code Fast 1 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Opus 4.8 or Grok Code Fast 1?
Claude Opus 4.8 — released May 28, 2026, about 9 months after Grok Code Fast 1.
Claude Opus 4.8 vs Grok Code Fast 1
Anthropic · US | xAI · US · Updated June 2026
Quick verdict
Pick Claude Opus 4.8 for agentic coding and multi-file debugging or long autonomous tasks. Pick Grok Code Fast 1 for fast, cheap agentic coding at $0.20/$1.50 or low-latency code generation and terminal tasks. On a tight budget at scale, Grok Code Fast 1 is the value pick.
Claude Opus 4.8 (Anthropic) and Grok Code Fast 1 (xAI) are two of the models people most often weigh against each other in 2026. Claude Opus 4.8 is the agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch. Grok Code Fast 1 is xAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: Grok Code Fast 1 is about 25× cheaper on input ($0.2/$1.5 per 1M tokens vs $5/$25 per 1M tokens) — a large enough gap that at scale it can be the single biggest line item in the decision.
▸Context window: Claude Opus 4.8 holds 3.9× more — 1M (~1,500 pages) vs 256K (~384 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: Claude Opus 4.8 is the newer model by about 9 months (released May 28, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Opus 4.8
Grok Code Fast 1
Provider
Anthropic (US)
xAI (US)
Released
May 28, 2026
August 28, 2025
Context window
1M (~1,500 pages)
256K (~384 pages)
Price (in/out)
$5/$25 per 1M tokens
$0.2/$1.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, code
SWE-Bench Verified
88.6%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Agentic coding and multi-file debugging
Claude Opus 4.8
Grok Code Fast 1 is comparatively weak here — a speed-tier coding model, not a frontier reasoner
Long autonomous tasks
Claude Opus 4.8
Its 1M window holds about 3.9× more than Grok Code Fast 1's 256K in a single prompt.
Honest uncertainty flagging
Claude Opus 4.8
The agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch — and it carries the larger 1M context.
Fast, cheap agentic coding at $0.20/$1.50
Grok Code Fast 1
At $0.2/$1.5 per 1M tokens it undercuts Claude Opus 4.8 ($5/$25 per 1M tokens), and that gap compounds at volume.
Low-latency code generation and terminal tasks
Grok Code Fast 1
XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality — and it runs cheaper at $0.2/$1.5 per 1M tokens.
High-volume coding pipelines where speed beats peak quality
Grok Code Fast 1
Claude Opus 4.8 is comparatively weak here — not the cheapest for high-volume work
Lowest cost at scale
Grok Code Fast 1
At $0.2/$1.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Claude Opus 4.8
Its 1M window is about 3.9× larger than Grok Code Fast 1's 256K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Grok Code Fast 1
At $0.2/$1.5 per 1M tokens it undercuts Claude Opus 4.8, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Claude Opus 4.8
Larger 1M window fits more in one prompt.
Anyone whose priority is agentic coding and multi-file debugging
→ Claude Opus 4.8
It is specifically built for that.
Anyone whose priority is fast, cheap agentic coding at $0.20/$1.50
→ Grok Code Fast 1
That is its strongest area.
Claude Opus 4.8: where it fits
The agentic-coding and judgment leader — highest SWE-Bench Pro score ever recorded at launch. Released May 28, 2026 by Anthropic, it is built for agentic coding and multi-file debugging, long autonomous tasks, honest uncertainty flagging, and professional writing and reasoning.
Its trade-offs are real: highest per-token price of the frontier tier, and not the cheapest for high-volume work. At $5 in / $25 out per million tokens, it sits in the premium price band.
Grok Code Fast 1: where it fits
XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. Released August 28, 2025 by xAI, it is built for fast, cheap agentic coding at $0.20/$1.50, low-latency code generation and terminal tasks, high-volume coding pipelines where speed beats peak quality, and a 256K window sized for real codebases.
Its trade-offs: text and code only — no image, audio or video input, xAI did not publish a SWE-Bench Verified score, a speed-tier coding model, not a frontier reasoner, and narrow focus — built for code, not general knowledge work. At $0.2 in / $1.5 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Claude Opus 4.8 and Grok Code Fast 1 overlap enough that the right pick depends on your specific job. Grok Code Fast 1 costs less per token; Claude Opus 4.8 holds the larger context; and each leads in its own area — Claude Opus 4.8 for agentic coding and multi-file debugging, Grok Code Fast 1 for fast, cheap agentic coding at $0.20/$1.50. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Opus 4.8 and Grok Code Fast 1 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
Is Claude Opus 4.8 or Grok Code Fast 1 better for coding?
Public SWE-Bench figures are not available for Grok Code Fast 1, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 4.8 leans toward agentic coding and multi-file debugging while Grok Code Fast 1 leans toward fast, cheap agentic coding at $0.20/$1.50, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 4.8 or Grok Code Fast 1?
Grok Code Fast 1 is cheaper — $5/$25 per 1M tokens vs $0.2/$1.5 per 1M tokens, roughly 25× apart on input.
Which has the bigger context window?
Claude Opus 4.8 — 1M vs 256K, about 3.9× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Opus 4.8 and Grok Code Fast 1 together?
Yes — a multi-model platform like LumiChats gives you Claude Opus 4.8, Grok Code Fast 1 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Opus 4.8 or Grok Code Fast 1?
Claude Opus 4.8 — released May 28, 2026, about 9 months after Grok Code Fast 1.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.