API cost decision in 10 seconds

NewGemini 3.5 Flash vs GPT-5.4 Pro

Pick Gemini 3.5 Flash for lower cost; pick GPT-5.4 Pro only if the larger context window matters more.

Pricing data updated: 2026-05-26T11:08:00Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Gemini 3.5 Flash for lower cost; pick GPT-5.4 Pro only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Gemini 3.5 Flash is estimated at $6 vs $120 for GPT-5.4 Pro, saving $114 (95% lower).

Cost-first pickGemini 3.5 Flash

Context-first pickGPT-5.4 Pro

Sample savings$11495%

10x traffic gap$1140

GPT-5.4 Pro has more context, but Gemini 3.5 Flash saves $114 on the standard workload. At 10x that traffic, the same price gap is about $1140. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Gemini 3.5 Flash stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Gemini 3.5 Flash	GPT-5.4 Pro
Input-heavy / RAG	5M input + 500K output	Gemini 3.5 Flash	$12	$240
Balanced workload	1M input + 1M output	Gemini 3.5 Flash	$10.5	$210
Output-heavy chatbot	1M input + 5M output	Gemini 3.5 Flash	$46.5	$930

Cheaper input Gemini 3.5 Flash $1.5 vs $30 / 1M

Gemini 3.5 Flash is $28.5 cheaper per 1M input tokens (95% lower; 20x difference).

Cheaper output Gemini 3.5 Flash $9 vs $180 / 1M

Gemini 3.5 Flash is $171 cheaper per 1M output tokens (95% lower; 20x difference).

Larger context GPT-5.4 Pro 1.05M vs 1.05M

GPT-5.4 Pro has 1.42K more context (1x larger).

Sample workload Gemini 3.5 Flash $6 vs $120

Gemini 3.5 Flash is $114 cheaper on the standard workload (95% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Gemini 3.5 Flash Calculating… Estimated API cost

GPT-5.4 Pro Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

Gemini 3.5 Flash has the lower input price; Gemini 3.5 Flash has the lower output price; GPT-5.4 Pro offers the larger context window. For the 1M input plus 500K output sample, Gemini 3.5 Flash is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $6 for Gemini 3.5 Flash and $120 for GPT-5.4 Pro.

Best Fit

Choose Gemini 3.5 Flash when you care most about lower input-token price, and lower output-token price.

Choose GPT-5.4 Pro when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, Gemini 3.5 Flash is estimated at $6 vs $120 for GPT-5.4 Pro, saving $114 (95% lower).
Gemini 3.5 Flash is $114 cheaper on the standard workload (95% lower).
Gemini 3.5 Flash is $28.5 cheaper per 1M input tokens (95% lower; 20x difference).
Gemini 3.5 Flash is $171 cheaper per 1M output tokens (95% lower; 20x difference).
GPT-5.4 Pro has 1.42K more context (1x larger).

Head-to-Head Specs

Feature	NewGemini 3.5 Flash (Google)	GPT-5.4 Pro (OpenAI)
Input Price prompt tokens per 1M	$1.5	$30
Completion Price per 1M tokens	$9	$180
Sample Workload Cost 1M input + 500K output	$6	$120
Context Window	1.05M	1.05M
Release Date	2026-05-19	2026-03-05

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Gemini 3.5 Flash	On the standard 1M input plus 500K output workload, Gemini 3.5 Flash is estimated at $6 vs $120 for GPT-5.4 Pro, saving $114 (95% lower).
High-volume input processing	Gemini 3.5 Flash	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Gemini 3.5 Flash	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	GPT-5.4 Pro	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Gemma 4 26B A4B (free) can replace Gemini 3.5 Flash when lower sample workload cost matters most: $0.
Gemma 4 31B (free) can replace Gemini 3.5 Flash when lower sample workload cost matters most: $0.
Lyria 3 Pro Preview can replace Gemini 3.5 Flash when lower sample workload cost matters most: $0.
Lyria 3 Clip Preview can replace Gemini 3.5 Flash when lower sample workload cost matters most: $0.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.

Popular competitors

No popular competitor is currently available.

Cheaper alternatives

Review low-cost models sorted by a standard 1M input plus 500K output workload.

Open cheapest models

Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

Open largest context models

Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

Open provider hubs

Google catalog

Review all tracked Google models before deciding whether this matchup is the right shortlist.

Open Google models

OpenAI catalog

Check other OpenAI models with comparable pricing, context, or release timing.

Open OpenAI models

Gemini 3.5 Flash

Gemini 3.5 Flash is Google's high-efficiency multimodal model, bringing near-Pro level coding and reasoning at Flash-tier cost and speed. It is highly optimized for coding proficiency and parallel agentic execution...

GPT-5.4 Pro

GPT-5.4 Pro is OpenAI's most advanced model, building on GPT-5.4's unified architecture with enhanced reasoning capabilities for complex, high-stakes tasks. It features a 1M+ token context window (922K input, 128K...