Pick GPT-5.4 for strong general-purpose default or coding and software engineering. 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.
GPT-5.4 (OpenAI) and Grok Code Fast 1 (xAI) are two of the models people most often weigh against each other in 2026. GPT-5.4 is openAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. 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 13× cheaper on input ($0.2/$1.5 per 1M tokens vs $2.5/$15 per 1M tokens) — a large enough gap that at scale it can be the single biggest line item in the decision.
Context window: GPT-5.4 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: GPT-5.4 is the newer model by about 6 months (released March 5, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
GPT-5.4
Grok Code Fast 1
Provider
OpenAI (US)
xAI (US)
Released
March 5, 2026
August 28, 2025
Context window
1M (~1,500 pages)
256K (~384 pages)
Price (in/out)
$2.5/$15 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
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Strong general-purpose default: GPT-5.4 — Grok Code Fast 1 is comparatively weak here — narrow focus — built for code, not general knowledge work
Coding and software engineering: GPT-5.4 — Grok Code Fast 1 is comparatively weak here — a speed-tier coding model, not a frontier reasoner
Document understanding and tool use: GPT-5.4 — Its 1M window holds about 3.9× more than Grok Code Fast 1's 256K in a single prompt.
Fast, cheap agentic coding at $0.20/$1.50: Grok Code Fast 1 — At $0.2/$1.5 per 1M tokens it undercuts GPT-5.4 ($2.5/$15 per 1M tokens), and that gap compounds at volume.
Low-latency code generation and terminal tasks: Grok Code Fast 1 — GPT-5.4 is comparatively weak here — topped by GPT-5.5 on the hardest tasks
High-volume coding pipelines where speed beats peak quality: 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.
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: GPT-5.4 — 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 GPT-5.4, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-5.4 — Larger 1M window fits more in one prompt.
Anyone whose priority is strong general-purpose default: GPT-5.4 — 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.
GPT-5.4: where it fits
OpenAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. Released March 5, 2026 by OpenAI, it is built for strong general-purpose default, coding and software engineering, document understanding and tool use, and 1M context with good token efficiency.
Its trade-offs are real: topped by GPT-5.5 on the hardest tasks, and pricier than open-weight rivals. At $2.5 in / $15 out per million tokens, it sits in the mid 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
GPT-5.4 and Grok Code Fast 1 overlap enough that the right pick depends on your specific job. Grok Code Fast 1 costs less per token; GPT-5.4 holds the larger context; and each leads in its own area — GPT-5.4 for strong general-purpose default, 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 GPT-5.4 or Grok Code Fast 1 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-5.4 leans toward strong general-purpose default 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, GPT-5.4 or Grok Code Fast 1?
Grok Code Fast 1 is cheaper — $2.5/$15 per 1M tokens vs $0.2/$1.5 per 1M tokens, roughly 13× apart on input.
Which has the bigger context window?
GPT-5.4 — 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 GPT-5.4 and Grok Code Fast 1 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.4, 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, GPT-5.4 or Grok Code Fast 1?
GPT-5.4 — released March 5, 2026, about 6 months after Grok Code Fast 1.
GPT-5.4 vs Grok Code Fast 1
OpenAI · US | xAI · US · Updated June 2026
Quick verdict
Pick GPT-5.4 for strong general-purpose default or coding and software engineering. 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.
GPT-5.4 (OpenAI) and Grok Code Fast 1 (xAI) are two of the models people most often weigh against each other in 2026. GPT-5.4 is openAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. 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 13× cheaper on input ($0.2/$1.5 per 1M tokens vs $2.5/$15 per 1M tokens) — a large enough gap that at scale it can be the single biggest line item in the decision.
▸Context window: GPT-5.4 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: GPT-5.4 is the newer model by about 6 months (released March 5, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
GPT-5.4
Grok Code Fast 1
Provider
OpenAI (US)
xAI (US)
Released
March 5, 2026
August 28, 2025
Context window
1M (~1,500 pages)
256K (~384 pages)
Price (in/out)
$2.5/$15 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
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Strong general-purpose default
GPT-5.4
Grok Code Fast 1 is comparatively weak here — narrow focus — built for code, not general knowledge work
Coding and software engineering
GPT-5.4
Grok Code Fast 1 is comparatively weak here — a speed-tier coding model, not a frontier reasoner
Document understanding and tool use
GPT-5.4
Its 1M window holds about 3.9× more than Grok Code Fast 1's 256K in a single prompt.
Fast, cheap agentic coding at $0.20/$1.50
Grok Code Fast 1
At $0.2/$1.5 per 1M tokens it undercuts GPT-5.4 ($2.5/$15 per 1M tokens), and that gap compounds at volume.
Low-latency code generation and terminal tasks
Grok Code Fast 1
GPT-5.4 is comparatively weak here — topped by GPT-5.5 on the hardest tasks
High-volume coding pipelines where speed beats peak quality
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.
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
GPT-5.4
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 GPT-5.4, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-5.4
Larger 1M window fits more in one prompt.
Anyone whose priority is strong general-purpose default
→ GPT-5.4
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.
GPT-5.4: where it fits
OpenAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. Released March 5, 2026 by OpenAI, it is built for strong general-purpose default, coding and software engineering, document understanding and tool use, and 1M context with good token efficiency.
Its trade-offs are real: topped by GPT-5.5 on the hardest tasks, and pricier than open-weight rivals. At $2.5 in / $15 out per million tokens, it sits in the mid 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
GPT-5.4 and Grok Code Fast 1 overlap enough that the right pick depends on your specific job. Grok Code Fast 1 costs less per token; GPT-5.4 holds the larger context; and each leads in its own area — GPT-5.4 for strong general-purpose default, 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 GPT-5.4 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.
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-5.4 leans toward strong general-purpose default 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, GPT-5.4 or Grok Code Fast 1?
Grok Code Fast 1 is cheaper — $2.5/$15 per 1M tokens vs $0.2/$1.5 per 1M tokens, roughly 13× apart on input.
Which has the bigger context window?
GPT-5.4 — 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 GPT-5.4 and Grok Code Fast 1 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.4, 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, GPT-5.4 or Grok Code Fast 1?
GPT-5.4 — released March 5, 2026, about 6 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.