Pick Gemini 3.8 Flash for long-horizon agentic coding (deepswe v1.1) or cost-efficient workhorse performance beating larger models at same price as 3.7 flash. Pick GPT-5.4 Mini for free for every chatgpt user or fast, low-cost general tasks.
Gemini 3.8 Flash (Google DeepMind) and GPT-5.4 Mini (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.8 Flash is google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research. GPT-5.4 Mini is openAI's free, fast workhorse — capable general AI with no subscription needed. Their biggest split is context window, and the breakdown below shows exactly how that plays out for your workload.
Key differences
Context window: Gemini 3.8 Flash holds 2.5× more — 1M tokens (~1,500 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 3.8 Flash is the newer model by about 6 months (released September 2, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Gemini 3.8 Flash
GPT-5.4 Mini
Provider
Google DeepMind (US)
OpenAI (US)
Released
September 2, 2026
March 17, 2026
Context window
1M tokens (~1,500 pages)
400K (~600 pages)
Price (in/out)
$0.75/$3.75 per 1M tokens
$0.75/$4.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, audio, video
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Long-horizon agentic coding (DeepSWE v1.1): Gemini 3.8 Flash — Its 1M tokens window holds about 2.5× more than GPT-5.4 Mini's 400K in a single prompt.
Cost-efficient workhorse performance beating larger models at same price as 3.7 Flash: Gemini 3.8 Flash — GPT-5.4 Mini is comparatively weak here — smaller context than flagship models
Vals Finance Agent V2 benchmark (61.4%, ahead of Claude Opus 5's 58.6%); also leads a weak field on the Harvey legal benchmark (10.0%): Gemini 3.8 Flash — Google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research — and it carries the larger 1M tokens context.
Free for every ChatGPT user: GPT-5.4 Mini — GPT-5.4 Mini lists free for every ChatGPT user among its strengths; Gemini 3.8 Flash does not.
Fast, low-cost general tasks: GPT-5.4 Mini — GPT-5.4 Mini lists fast, low-cost general tasks among its strengths; Gemini 3.8 Flash does not.
Subagent capabilities: GPT-5.4 Mini — GPT-5.4 Mini lists subagent capabilities among its strengths; Gemini 3.8 Flash does not.
Largest single-prompt input: Gemini 3.8 Flash — Its 1M tokens window is about 2.5× larger than GPT-5.4 Mini's 400K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
Someone analysing very long documents or codebases: Gemini 3.8 Flash — Larger 1M tokens window fits more in one prompt.
Anyone whose priority is long-horizon agentic coding (deepswe v1.1): Gemini 3.8 Flash — It is specifically built for that.
Anyone whose priority is free for every chatgpt user: GPT-5.4 Mini — That is its strongest area.
Gemini 3.8 Flash: where it fits
Google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research. Released September 2, 2026 by Google DeepMind, it is built for long-horizon agentic coding (DeepSWE v1.1), cost-efficient workhorse performance beating larger models at same price as 3.7 Flash, vals Finance Agent V2 benchmark (61.4%, ahead of Claude Opus 5's 58.6%); also leads a weak field on the Harvey legal benchmark (10.0%), and prompt-injection robustness (Gray Swan benchmark).
Its trade-offs are real: still a mid-tier 'Flash' model, not Google's frontier flagship (which remains unreleased), introductory price doubles on January 1, 2027, hLE-Verified score (54.9%) trails top frontier reasoning models, and built on the same base model as Gemini 3.7 Flash (a post-training update, not a freshly pretrained model). At $0.75 in / $3.75 out per million tokens, it sits in the budget price band.
GPT-5.4 Mini: where it fits
OpenAI's free, fast workhorse — capable general AI with no subscription needed. Released March 17, 2026 by OpenAI, it is built for free for every ChatGPT user, fast, low-cost general tasks, subagent capabilities, and native multimodal reasoning.
Its trade-offs: smaller context than flagship models, and not for the hardest reasoning. At $0.75 in / $4.5 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Gemini 3.8 Flash and GPT-5.4 Mini overlap enough that the right pick depends on your specific job. Gemini 3.8 Flash holds the larger context; and each leads in its own area — Gemini 3.8 Flash for long-horizon agentic coding (deepswe v1.1), GPT-5.4 Mini for free for every chatgpt user. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Gemini 3.8 Flash or GPT-5.4 Mini 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 3.8 Flash leans toward long-horizon agentic coding (deepswe v1.1) while GPT-5.4 Mini leans toward free for every chatgpt user, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Gemini 3.8 Flash or GPT-5.4 Mini?
They are priced almost identically, so cost will not decide between them.
Which has the bigger context window?
Gemini 3.8 Flash — 1M tokens vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Gemini 3.8 Flash and GPT-5.4 Mini together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.8 Flash, GPT-5.4 Mini 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 3.8 Flash or GPT-5.4 Mini?
Gemini 3.8 Flash — released September 2, 2026, about 6 months after GPT-5.4 Mini.
Gemini 3.8 Flash vs GPT-5.4 Mini
Google DeepMind · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Gemini 3.8 Flash for long-horizon agentic coding (deepswe v1.1) or cost-efficient workhorse performance beating larger models at same price as 3.7 flash. Pick GPT-5.4 Mini for free for every chatgpt user or fast, low-cost general tasks.
Gemini 3.8 Flash (Google DeepMind) and GPT-5.4 Mini (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.8 Flash is google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research. GPT-5.4 Mini is openAI's free, fast workhorse — capable general AI with no subscription needed. Their biggest split is context window, and the breakdown below shows exactly how that plays out for your workload.
Key differences at a glance
▸Context window: Gemini 3.8 Flash holds 2.5× more — 1M tokens (~1,500 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 3.8 Flash is the newer model by about 6 months (released September 2, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Gemini 3.8 Flash
GPT-5.4 Mini
Provider
Google DeepMind (US)
OpenAI (US)
Released
September 2, 2026
March 17, 2026
Context window
1M tokens (~1,500 pages)
400K (~600 pages)
Price (in/out)
$0.75/$3.75 per 1M tokens
$0.75/$4.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, audio, video
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Long-horizon agentic coding (DeepSWE v1.1)
Gemini 3.8 Flash
Its 1M tokens window holds about 2.5× more than GPT-5.4 Mini's 400K in a single prompt.
Cost-efficient workhorse performance beating larger models at same price as 3.7 Flash
Gemini 3.8 Flash
GPT-5.4 Mini is comparatively weak here — smaller context than flagship models
Vals Finance Agent V2 benchmark (61.4%, ahead of Claude Opus 5's 58.6%); also leads a weak field on the Harvey legal benchmark (10.0%)
Gemini 3.8 Flash
Google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research — and it carries the larger 1M tokens context.
Free for every ChatGPT user
GPT-5.4 Mini
GPT-5.4 Mini lists free for every ChatGPT user among its strengths; Gemini 3.8 Flash does not.
Fast, low-cost general tasks
GPT-5.4 Mini
GPT-5.4 Mini lists fast, low-cost general tasks among its strengths; Gemini 3.8 Flash does not.
Subagent capabilities
GPT-5.4 Mini
GPT-5.4 Mini lists subagent capabilities among its strengths; Gemini 3.8 Flash does not.
Largest single-prompt input
Gemini 3.8 Flash
Its 1M tokens window is about 2.5× larger than GPT-5.4 Mini's 400K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
Someone analysing very long documents or codebases
→ Gemini 3.8 Flash
Larger 1M tokens window fits more in one prompt.
Anyone whose priority is long-horizon agentic coding (deepswe v1.1)
→ Gemini 3.8 Flash
It is specifically built for that.
Anyone whose priority is free for every chatgpt user
→ GPT-5.4 Mini
That is its strongest area.
Gemini 3.8 Flash: where it fits
Google's cost-efficient workhorse model released September 2, 2026, tuned for long-horizon coding and autonomous agents, launched alongside a restricted 'Cyber' variant for vulnerability research. Released September 2, 2026 by Google DeepMind, it is built for long-horizon agentic coding (DeepSWE v1.1), cost-efficient workhorse performance beating larger models at same price as 3.7 Flash, vals Finance Agent V2 benchmark (61.4%, ahead of Claude Opus 5's 58.6%); also leads a weak field on the Harvey legal benchmark (10.0%), and prompt-injection robustness (Gray Swan benchmark).
Its trade-offs are real: still a mid-tier 'Flash' model, not Google's frontier flagship (which remains unreleased), introductory price doubles on January 1, 2027, hLE-Verified score (54.9%) trails top frontier reasoning models, and built on the same base model as Gemini 3.7 Flash (a post-training update, not a freshly pretrained model). At $0.75 in / $3.75 out per million tokens, it sits in the budget price band.
GPT-5.4 Mini: where it fits
OpenAI's free, fast workhorse — capable general AI with no subscription needed. Released March 17, 2026 by OpenAI, it is built for free for every ChatGPT user, fast, low-cost general tasks, subagent capabilities, and native multimodal reasoning.
Its trade-offs: smaller context than flagship models, and not for the hardest reasoning. At $0.75 in / $4.5 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Gemini 3.8 Flash and GPT-5.4 Mini overlap enough that the right pick depends on your specific job. Gemini 3.8 Flash holds the larger context; and each leads in its own area — Gemini 3.8 Flash for long-horizon agentic coding (deepswe v1.1), GPT-5.4 Mini for free for every chatgpt user. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Gemini 3.8 Flash and GPT-5.4 Mini 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 Gemini 3.8 Flash or GPT-5.4 Mini 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 3.8 Flash leans toward long-horizon agentic coding (deepswe v1.1) while GPT-5.4 Mini leans toward free for every chatgpt user, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Gemini 3.8 Flash or GPT-5.4 Mini?
They are priced almost identically, so cost will not decide between them.
Which has the bigger context window?
Gemini 3.8 Flash — 1M tokens vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Gemini 3.8 Flash and GPT-5.4 Mini together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.8 Flash, GPT-5.4 Mini 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 3.8 Flash or GPT-5.4 Mini?
Gemini 3.8 Flash — released September 2, 2026, about 6 months after GPT-5.4 Mini.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.