Pick Gemini 3.1 Pro for full multimodal input — text, image, audio and video in one 1m-token window or long video and document analysis. 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, GPT-5.1 is the value pick.
Gemini 3.1 Pro (Google) and GPT-5.1 (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.1 Pro is a 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window. 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: GPT-5.1 is about 1.6× cheaper on input ($1.25/$10 per 1M tokens vs $2/$12 per 1M tokens) — modest, but it adds up at steady volume.
Context window: Gemini 3.1 Pro holds 2.6× more — 1M (~1,573 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: Gemini 3.1 Pro is the newer model by about 3 months (released February 19, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Gemini 3.1 Pro
GPT-5.1
Provider
Google (US)
OpenAI (US)
Released
February 19, 2026
November 13, 2025
Context window
1M (~1,573 pages)
400K (~600 pages)
Price (in/out)
$2/$12 per 1M tokens
$1.25/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, audio, video, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
26.3%
Not published
Who wins what
Full multimodal input — text, image, audio and video in one 1M-token window: Gemini 3.1 Pro — Its 1M window holds about 2.6× more than GPT-5.1's 400K in a single prompt.
Long video and document analysis: Gemini 3.1 Pro — A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window — and it carries the larger 1M context.
Agentic reasoning (high ARC-AGI-2): Gemini 3.1 Pro — A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window — and it is the newer of the two.
Adaptive reasoning that scales compute to task difficulty: GPT-5.1 — At $1.25/$10 per 1M tokens it undercuts Gemini 3.1 Pro ($2/$12 per 1M tokens), and that gap compounds at volume.
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 runs cheaper at $1.25/$10 per 1M tokens.
A large ~400K context for long documents and sessions: GPT-5.1 — Gemini 3.1 Pro is comparatively weak here — long-context recall drops sharply past 256K (26.3% on MRCR v2 at 1M)
Lowest cost at scale: GPT-5.1 — At $1.25/$10 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: Gemini 3.1 Pro — Its 1M window is about 2.6× larger than GPT-5.1's 400K, fitting roughly 1,573 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: GPT-5.1 — At $1.25/$10 per 1M tokens it undercuts Gemini 3.1 Pro, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Gemini 3.1 Pro — Larger 1M window fits more in one prompt.
Anyone whose priority is full multimodal input — text, image, audio and video in one 1m-token window: Gemini 3.1 Pro — 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.
Gemini 3.1 Pro: where it fits
A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window. Released February 19, 2026 by Google, it is built for full multimodal input — text, image, audio and video in one 1M-token window, long video and document analysis, agentic reasoning (high ARC-AGI-2), and broad multimodal understanding across formats.
Its trade-offs are real: long-context recall drops sharply past 256K (26.3% on MRCR v2 at 1M), premium price per token at $2/$12, and superseded within Google's own line by the newer 3.5/3.6 Flash releases for cost-sensitive work. At $2 in / $12 out per million tokens, it sits in the mid 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
Gemini 3.1 Pro and GPT-5.1 overlap enough that the right pick depends on your specific job. GPT-5.1 costs less per token; Gemini 3.1 Pro holds the larger context; and each leads in its own area — Gemini 3.1 Pro for full multimodal input — text, image, audio and video in one 1m-token window, 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 Gemini 3.1 Pro or GPT-5.1 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, Gemini 3.1 Pro leans toward full multimodal input — text, image, audio and video in one 1m-token window 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, Gemini 3.1 Pro or GPT-5.1?
GPT-5.1 is cheaper — $2/$12 per 1M tokens vs $1.25/$10 per 1M tokens, roughly 1.6× apart on input.
Which has the bigger context window?
Gemini 3.1 Pro — 1M vs 400K, about 2.6× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Gemini 3.1 Pro and GPT-5.1 together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.1 Pro, 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, Gemini 3.1 Pro or GPT-5.1?
Gemini 3.1 Pro — released February 19, 2026, about 3 months after GPT-5.1.
Gemini 3.1 Pro vs GPT-5.1
Google · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Gemini 3.1 Pro for full multimodal input — text, image, audio and video in one 1m-token window or long video and document analysis. 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, GPT-5.1 is the value pick.
Gemini 3.1 Pro (Google) and GPT-5.1 (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.1 Pro is a 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window. 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: GPT-5.1 is about 1.6× cheaper on input ($1.25/$10 per 1M tokens vs $2/$12 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: Gemini 3.1 Pro holds 2.6× more — 1M (~1,573 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: Gemini 3.1 Pro is the newer model by about 3 months (released February 19, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Gemini 3.1 Pro
GPT-5.1
Provider
Google (US)
OpenAI (US)
Released
February 19, 2026
November 13, 2025
Context window
1M (~1,573 pages)
400K (~600 pages)
Price (in/out)
$2/$12 per 1M tokens
$1.25/$10 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, audio, video, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
26.3%
Not published
Who wins what
Full multimodal input — text, image, audio and video in one 1M-token window
Gemini 3.1 Pro
Its 1M window holds about 2.6× more than GPT-5.1's 400K in a single prompt.
Long video and document analysis
Gemini 3.1 Pro
A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window — and it carries the larger 1M context.
Agentic reasoning (high ARC-AGI-2)
Gemini 3.1 Pro
A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window — and it is the newer of the two.
Adaptive reasoning that scales compute to task difficulty
GPT-5.1
At $1.25/$10 per 1M tokens it undercuts Gemini 3.1 Pro ($2/$12 per 1M tokens), and that gap compounds at volume.
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 runs cheaper at $1.25/$10 per 1M tokens.
A large ~400K context for long documents and sessions
GPT-5.1
Gemini 3.1 Pro is comparatively weak here — long-context recall drops sharply past 256K (26.3% on MRCR v2 at 1M)
Lowest cost at scale
GPT-5.1
At $1.25/$10 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Gemini 3.1 Pro
Its 1M window is about 2.6× larger than GPT-5.1's 400K, fitting roughly 1,573 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.1
At $1.25/$10 per 1M tokens it undercuts Gemini 3.1 Pro, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Gemini 3.1 Pro
Larger 1M window fits more in one prompt.
Anyone whose priority is full multimodal input — text, image, audio and video in one 1m-token window
→ Gemini 3.1 Pro
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.
Gemini 3.1 Pro: where it fits
A 1M-token multimodal workhorse — huge breadth across text, image, audio and video, but recall fades deep in the window. Released February 19, 2026 by Google, it is built for full multimodal input — text, image, audio and video in one 1M-token window, long video and document analysis, agentic reasoning (high ARC-AGI-2), and broad multimodal understanding across formats.
Its trade-offs are real: long-context recall drops sharply past 256K (26.3% on MRCR v2 at 1M), premium price per token at $2/$12, and superseded within Google's own line by the newer 3.5/3.6 Flash releases for cost-sensitive work. At $2 in / $12 out per million tokens, it sits in the mid 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
Gemini 3.1 Pro and GPT-5.1 overlap enough that the right pick depends on your specific job. GPT-5.1 costs less per token; Gemini 3.1 Pro holds the larger context; and each leads in its own area — Gemini 3.1 Pro for full multimodal input — text, image, audio and video in one 1m-token window, 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 Gemini 3.1 Pro 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 either model, so the honest test is your own repository — run an identical real bug through both. By design, Gemini 3.1 Pro leans toward full multimodal input — text, image, audio and video in one 1m-token window 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, Gemini 3.1 Pro or GPT-5.1?
GPT-5.1 is cheaper — $2/$12 per 1M tokens vs $1.25/$10 per 1M tokens, roughly 1.6× apart on input.
Which has the bigger context window?
Gemini 3.1 Pro — 1M vs 400K, about 2.6× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Gemini 3.1 Pro and GPT-5.1 together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.1 Pro, 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, Gemini 3.1 Pro or GPT-5.1?
Gemini 3.1 Pro — released February 19, 2026, about 3 months after GPT-5.1.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.