Pick Gemini 3.5 Flash for speed — roughly 4x faster than rivals or cost — about a third the price. Pick GPT-5.4 for strong general-purpose default or coding and software engineering. On a tight budget at scale, Gemini 3.5 Flash is the value pick.
Gemini 3.5 Flash (Google) and GPT-5.4 (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.5 Flash is google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. GPT-5.4 is openAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. Their biggest split is price, and the breakdown below shows exactly how that plays out for your workload.
Key differences
Price: Gemini 3.5 Flash is about 1.7× cheaper on input ($1.5/$9 per 1M tokens vs $2.5/$15 per 1M tokens) — modest, but it adds up at steady volume.
Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
Recency: Gemini 3.5 Flash is the newer model by about 3 months (released May 19, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Gemini 3.5 Flash
GPT-5.4
Provider
Google (US)
OpenAI (US)
Released
May 19, 2026
March 5, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$1.5/$9 per 1M tokens
$2.5/$15 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
Not published
Not published
Who wins what
Speed — roughly 4x faster than rivals: Gemini 3.5 Flash — GPT-5.4 is comparatively weak here — pricier than open-weight rivals
Cost — about a third the price: Gemini 3.5 Flash — At $1.5/$9 per 1M tokens it undercuts GPT-5.4 ($2.5/$15 per 1M tokens), and that gap compounds at volume.
Default in the Gemini app and Search AI Mode: Gemini 3.5 Flash — Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play — and it runs cheaper at $1.5/$9 per 1M tokens.
Strong general-purpose default: GPT-5.4 — GPT-5.4 lists strong general-purpose default among its strengths; Gemini 3.5 Flash does not.
Coding and software engineering: GPT-5.4 — GPT-5.4 lists coding and software engineering among its strengths; Gemini 3.5 Flash does not.
Document understanding and tool use: GPT-5.4 — GPT-5.4 lists document understanding and tool use among its strengths; Gemini 3.5 Flash does not.
Lowest cost at scale: Gemini 3.5 Flash — At $1.5/$9 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume: Gemini 3.5 Flash — At $1.5/$9 per 1M tokens it undercuts GPT-5.4, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is speed — roughly 4x faster than rivals: Gemini 3.5 Flash — It is specifically built for that.
Anyone whose priority is strong general-purpose default: GPT-5.4 — That is its strongest area.
Gemini 3.5 Flash: where it fits
Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. Released May 19, 2026 by Google, it is built for speed — roughly 4x faster than rivals, cost — about a third the price, default in the Gemini app and Search AI Mode, and high-volume multimodal work.
Its trade-offs are real: flash tier, not the deepest reasoning, and pro-tier 3.5 held back at launch. At $1.5 in / $9 out per million tokens, it sits in the mid price band.
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: 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.
The bottom line for this matchup
Gemini 3.5 Flash and GPT-5.4 overlap enough that the right pick depends on your specific job. Gemini 3.5 Flash costs less per token; and each leads in its own area — Gemini 3.5 Flash for speed — roughly 4x faster than rivals, GPT-5.4 for strong general-purpose default. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Gemini 3.5 Flash or GPT-5.4 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 3.5 Flash leans toward speed — roughly 4x faster than rivals while GPT-5.4 leans toward strong general-purpose default, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Gemini 3.5 Flash or GPT-5.4?
Gemini 3.5 Flash is cheaper — $1.5/$9 per 1M tokens vs $2.5/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Gemini 3.5 Flash and GPT-5.4 together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.5 Flash, GPT-5.4 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 3.5 Flash or GPT-5.4?
Gemini 3.5 Flash — released May 19, 2026, about 3 months after GPT-5.4.
Gemini 3.5 Flash vs GPT-5.4
Google · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Gemini 3.5 Flash for speed — roughly 4x faster than rivals or cost — about a third the price. Pick GPT-5.4 for strong general-purpose default or coding and software engineering. On a tight budget at scale, Gemini 3.5 Flash is the value pick.
Gemini 3.5 Flash (Google) and GPT-5.4 (OpenAI) are two of the models people most often weigh against each other in 2026. Gemini 3.5 Flash is google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. GPT-5.4 is openAI's 2026 workhorse — unifies Codex and GPT into a strong default that costs half of GPT-5.5. Their biggest split is price, and the breakdown below shows exactly how that plays out for your workload.
Key differences at a glance
▸Price: Gemini 3.5 Flash is about 1.7× cheaper on input ($1.5/$9 per 1M tokens vs $2.5/$15 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
▸Recency: Gemini 3.5 Flash is the newer model by about 3 months (released May 19, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Gemini 3.5 Flash
GPT-5.4
Provider
Google (US)
OpenAI (US)
Released
May 19, 2026
March 5, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$1.5/$9 per 1M tokens
$2.5/$15 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
Not published
Not published
Who wins what
Speed — roughly 4x faster than rivals
Gemini 3.5 Flash
GPT-5.4 is comparatively weak here — pricier than open-weight rivals
Cost — about a third the price
Gemini 3.5 Flash
At $1.5/$9 per 1M tokens it undercuts GPT-5.4 ($2.5/$15 per 1M tokens), and that gap compounds at volume.
Default in the Gemini app and Search AI Mode
Gemini 3.5 Flash
Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play — and it runs cheaper at $1.5/$9 per 1M tokens.
Strong general-purpose default
GPT-5.4
GPT-5.4 lists strong general-purpose default among its strengths; Gemini 3.5 Flash does not.
Coding and software engineering
GPT-5.4
GPT-5.4 lists coding and software engineering among its strengths; Gemini 3.5 Flash does not.
Document understanding and tool use
GPT-5.4
GPT-5.4 lists document understanding and tool use among its strengths; Gemini 3.5 Flash does not.
Lowest cost at scale
Gemini 3.5 Flash
At $1.5/$9 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Gemini 3.5 Flash
At $1.5/$9 per 1M tokens it undercuts GPT-5.4, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is speed — roughly 4x faster than rivals
→ Gemini 3.5 Flash
It is specifically built for that.
Anyone whose priority is strong general-purpose default
→ GPT-5.4
That is its strongest area.
Gemini 3.5 Flash: where it fits
Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. Released May 19, 2026 by Google, it is built for speed — roughly 4x faster than rivals, cost — about a third the price, default in the Gemini app and Search AI Mode, and high-volume multimodal work.
Its trade-offs are real: flash tier, not the deepest reasoning, and pro-tier 3.5 held back at launch. At $1.5 in / $9 out per million tokens, it sits in the mid price band.
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: 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.
The bottom line for this matchup
Gemini 3.5 Flash and GPT-5.4 overlap enough that the right pick depends on your specific job. Gemini 3.5 Flash costs less per token; and each leads in its own area — Gemini 3.5 Flash for speed — roughly 4x faster than rivals, GPT-5.4 for strong general-purpose default. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Gemini 3.5 Flash and GPT-5.4 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 3.5 Flash leans toward speed — roughly 4x faster than rivals while GPT-5.4 leans toward strong general-purpose default, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Gemini 3.5 Flash or GPT-5.4?
Gemini 3.5 Flash is cheaper — $1.5/$9 per 1M tokens vs $2.5/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Gemini 3.5 Flash and GPT-5.4 together?
Yes — a multi-model platform like LumiChats gives you Gemini 3.5 Flash, GPT-5.4 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 3.5 Flash or GPT-5.4?
Gemini 3.5 Flash — released May 19, 2026, about 3 months after GPT-5.4.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.