Pick Claude Haiku 4.5 for fastest claude model or near-frontier coding for its tier — 73.3% on swe-bench verified. Pick GPT-5.1 for adaptive reasoning that scales compute to task difficulty or general-purpose reasoning, coding and tool use. On a tight budget at scale, Claude Haiku 4.5 is the value pick.
Claude Haiku 4.5 (Anthropic) and GPT-5.1 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Haiku 4.5 is anthropic's fastest, most compact model — built for speed and volume. GPT-5.1 is openAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: nearly identical — $1/$5 per 1M tokens vs $1.25/$10 per 1M tokens. Cost will not be the deciding factor here.
Context window: GPT-5.1 holds 2× more — 400K (~600 pages) vs 200K (~300 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-5.1 is the newer model by about 29 days (released November 13, 2025), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Haiku 4.5
GPT-5.1
Provider
Anthropic (US)
OpenAI (US)
Released
October 15, 2025
November 13, 2025
Context window
200K (~300 pages)
400K (~600 pages)
Price (in/out)
$1/$5 per 1M tokens
$1.25/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
73.3%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Fastest Claude model: Claude Haiku 4.5 — GPT-5.1 is comparatively weak here — premium output price at $10/1M for a now-older model
Near-frontier coding for its tier — 73.3% on SWE-Bench Verified: Claude Haiku 4.5 — GPT-5.1 is comparatively weak here — no reliably published SWE-Bench Verified figure
Low-latency, high-volume API calls: Claude Haiku 4.5 — At $1/$5 per 1M tokens it undercuts GPT-5.1 ($1.25/$10 per 1M tokens), and that gap compounds at volume.
Adaptive reasoning that scales compute to task difficulty: GPT-5.1 — Claude Haiku 4.5 is comparatively weak here — not for deep reasoning
General-purpose reasoning, coding and tool use: GPT-5.1 — OpenAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line — and it carries the larger 400K context.
A large ~400K context for long documents and sessions: GPT-5.1 — Its 400K window holds about 2× more than Claude Haiku 4.5's 200K in a single prompt.
Lowest cost at scale: Claude Haiku 4.5 — At $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-5.1 — Its 400K window is about 2× larger than Claude Haiku 4.5's 200K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Claude Haiku 4.5 — At $1/$5 per 1M tokens it undercuts GPT-5.1, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-5.1 — Larger 400K window fits more in one prompt.
Anyone whose priority is fastest claude model: Claude Haiku 4.5 — It is specifically built for that.
Anyone whose priority is adaptive reasoning that scales compute to task difficulty: GPT-5.1 — That is its strongest area.
Claude Haiku 4.5: where it fits
Anthropic's fastest, most compact model — built for speed and volume. Released October 15, 2025 by Anthropic, it is built for fastest Claude model, near-frontier coding for its tier — 73.3% on SWE-Bench Verified, low-latency, high-volume API calls, and cheapest Claude tier at $1/$5.
Its trade-offs are real: smallest context in the family (200K), and not for deep reasoning. At $1 in / $5 out per million tokens, it sits in the budget price band.
GPT-5.1: where it fits
OpenAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line. Released November 13, 2025 by OpenAI, it is built for adaptive reasoning that scales compute to task difficulty, general-purpose reasoning, coding and tool use, a large ~400K context for long documents and sessions, and text and image input.
Its trade-offs: superseded by GPT-5.2 through GPT-5.6 — kept for compatibility rather than being current, no reliably published SWE-Bench Verified figure, exact context window unconfirmed (400K vs 410K across trackers), and premium output price at $10/1M for a now-older model. At $1.25 in / $10 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Haiku 4.5 and GPT-5.1 overlap enough that the right pick depends on your specific job. Claude Haiku 4.5 costs less per token; GPT-5.1 holds the larger context; and each leads in its own area — Claude Haiku 4.5 for fastest claude model, GPT-5.1 for adaptive reasoning that scales compute to task difficulty. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Haiku 4.5 or GPT-5.1 better for coding?
Public SWE-Bench figures are not available for GPT-5.1, so the honest test is your own repository — run an identical real bug through both. By design, Claude Haiku 4.5 leans toward fastest claude model while GPT-5.1 leans toward adaptive reasoning that scales compute to task difficulty, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Haiku 4.5 or GPT-5.1?
Claude Haiku 4.5 is cheaper — $1/$5 per 1M tokens vs $1.25/$10 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.1 — 400K vs 200K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Haiku 4.5 and GPT-5.1 together?
Yes — a multi-model platform like LumiChats gives you Claude Haiku 4.5, GPT-5.1 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 Haiku 4.5 or GPT-5.1?
GPT-5.1 — released November 13, 2025, about 29 days after Claude Haiku 4.5.
Claude Haiku 4.5 vs GPT-5.1
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Haiku 4.5 for fastest claude model or near-frontier coding for its tier — 73.3% on swe-bench verified. Pick GPT-5.1 for adaptive reasoning that scales compute to task difficulty or general-purpose reasoning, coding and tool use. On a tight budget at scale, Claude Haiku 4.5 is the value pick.
Claude Haiku 4.5 (Anthropic) and GPT-5.1 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Haiku 4.5 is anthropic's fastest, most compact model — built for speed and volume. GPT-5.1 is openAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: nearly identical — $1/$5 per 1M tokens vs $1.25/$10 per 1M tokens. Cost will not be the deciding factor here.
▸Context window: GPT-5.1 holds 2× more — 400K (~600 pages) vs 200K (~300 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-5.1 is the newer model by about 29 days (released November 13, 2025), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Haiku 4.5
GPT-5.1
Provider
Anthropic (US)
OpenAI (US)
Released
October 15, 2025
November 13, 2025
Context window
200K (~300 pages)
400K (~600 pages)
Price (in/out)
$1/$5 per 1M tokens
$1.25/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
73.3%
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Fastest Claude model
Claude Haiku 4.5
GPT-5.1 is comparatively weak here — premium output price at $10/1M for a now-older model
Near-frontier coding for its tier — 73.3% on SWE-Bench Verified
Claude Haiku 4.5
GPT-5.1 is comparatively weak here — no reliably published SWE-Bench Verified figure
Low-latency, high-volume API calls
Claude Haiku 4.5
At $1/$5 per 1M tokens it undercuts GPT-5.1 ($1.25/$10 per 1M tokens), and that gap compounds at volume.
Adaptive reasoning that scales compute to task difficulty
GPT-5.1
Claude Haiku 4.5 is comparatively weak here — not for deep reasoning
General-purpose reasoning, coding and tool use
GPT-5.1
OpenAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line — and it carries the larger 400K context.
A large ~400K context for long documents and sessions
GPT-5.1
Its 400K window holds about 2× more than Claude Haiku 4.5's 200K in a single prompt.
Lowest cost at scale
Claude Haiku 4.5
At $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-5.1
Its 400K window is about 2× larger than Claude Haiku 4.5's 200K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Claude Haiku 4.5
At $1/$5 per 1M tokens it undercuts GPT-5.1, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-5.1
Larger 400K window fits more in one prompt.
Anyone whose priority is fastest claude model
→ Claude Haiku 4.5
It is specifically built for that.
Anyone whose priority is adaptive reasoning that scales compute to task difficulty
→ GPT-5.1
That is its strongest area.
Claude Haiku 4.5: where it fits
Anthropic's fastest, most compact model — built for speed and volume. Released October 15, 2025 by Anthropic, it is built for fastest Claude model, near-frontier coding for its tier — 73.3% on SWE-Bench Verified, low-latency, high-volume API calls, and cheapest Claude tier at $1/$5.
Its trade-offs are real: smallest context in the family (200K), and not for deep reasoning. At $1 in / $5 out per million tokens, it sits in the budget price band.
GPT-5.1: where it fits
OpenAI's late-2025 GPT-5.1 at $1.25/$10 — a capable general model since surpassed by the GPT-5.2–5.6 line. Released November 13, 2025 by OpenAI, it is built for adaptive reasoning that scales compute to task difficulty, general-purpose reasoning, coding and tool use, a large ~400K context for long documents and sessions, and text and image input.
Its trade-offs: superseded by GPT-5.2 through GPT-5.6 — kept for compatibility rather than being current, no reliably published SWE-Bench Verified figure, exact context window unconfirmed (400K vs 410K across trackers), and premium output price at $10/1M for a now-older model. At $1.25 in / $10 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Haiku 4.5 and GPT-5.1 overlap enough that the right pick depends on your specific job. Claude Haiku 4.5 costs less per token; GPT-5.1 holds the larger context; and each leads in its own area — Claude Haiku 4.5 for fastest claude model, GPT-5.1 for adaptive reasoning that scales compute to task difficulty. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Haiku 4.5 and GPT-5.1 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 GPT-5.1, so the honest test is your own repository — run an identical real bug through both. By design, Claude Haiku 4.5 leans toward fastest claude model while GPT-5.1 leans toward adaptive reasoning that scales compute to task difficulty, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Haiku 4.5 or GPT-5.1?
Claude Haiku 4.5 is cheaper — $1/$5 per 1M tokens vs $1.25/$10 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.1 — 400K vs 200K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Haiku 4.5 and GPT-5.1 together?
Yes — a multi-model platform like LumiChats gives you Claude Haiku 4.5, GPT-5.1 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 Haiku 4.5 or GPT-5.1?
GPT-5.1 — released November 13, 2025, about 29 days after Claude Haiku 4.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.