API cost decision in 10 seconds

New🔥Gemini 3.5 Flash vs GPT-5 Chat

Pick Gemini 3.5 Flash when budget and context both matter.

Page updated: 2026-05-26T15:08:08Z Data confirmed: 2026-05-26T18:08:02Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Gemini 3.5 Flash when budget and context both matter.

On the standard 1M input plus 500K output workload, Gemini 3.5 Flash is estimated at $6 vs $6.25 for GPT-5 Chat, saving $0.25 (4% lower).

Cost-first pickGemini 3.5 Flash

Context-first pickGemini 3.5 Flash

Sample savings$0.254%

10x traffic gap$2.5

Gemini 3.5 Flash is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $2.5. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Cost winner changes by workload shape: input-heavy / RAG favors GPT-5 Chat, balanced workload favors Gemini 3.5 Flash, and output-heavy chatbot favors Gemini 3.5 Flash.

Workload shape	Token mix	Better pick	Gemini 3.5 Flash	GPT-5 Chat
Input-heavy / RAG	5M input + 500K output	GPT-5 Chat	$12	$11.25
Balanced workload	1M input + 1M output	Gemini 3.5 Flash	$10.5	$11.25
Output-heavy chatbot	1M input + 5M output	Gemini 3.5 Flash	$46.5	$51.25

Cheaper input GPT-5 Chat $1.5 vs $1.25 / 1M

GPT-5 Chat is $0.25 cheaper per 1M input tokens (16.7% lower; 1.2x difference).

Cheaper output Gemini 3.5 Flash $9 vs $10 / 1M

Gemini 3.5 Flash is $1 cheaper per 1M output tokens (10% lower; 1.11x difference).

Larger context Gemini 3.5 Flash 1.05M vs 128K

Gemini 3.5 Flash has 920.58K more context (8.19x larger).

Sample workload Gemini 3.5 Flash $6 vs $6.25

Gemini 3.5 Flash is $0.25 cheaper on the standard workload (4% 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 Chat 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

GPT-5 Chat has the lower input price; Gemini 3.5 Flash has the lower output price; Gemini 3.5 Flash 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 $6.25 for GPT-5 Chat.

Best Fit

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

Choose GPT-5 Chat when you care most about lower input-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Gemini 3.5 Flash is estimated at $6 vs $6.25 for GPT-5 Chat, saving $0.25 (4% lower).
Gemini 3.5 Flash is $0.25 cheaper on the standard workload (4% lower).
GPT-5 Chat is $0.25 cheaper per 1M input tokens (16.7% lower; 1.2x difference).
Gemini 3.5 Flash is $1 cheaper per 1M output tokens (10% lower; 1.11x difference).
Gemini 3.5 Flash has 920.58K more context (8.19x larger).

Head-to-Head Specs

Feature	New🔥Gemini 3.5 Flash (Google)	GPT-5 Chat (OpenAI)
Input Price prompt tokens per 1M	$1.5	$1.25
Completion Price per 1M tokens	$9	$10
Sample Workload Cost 1M input + 500K output	$6	$6.25
Context Window	1.05M	128K
Release Date	2026-05-19	2025-08-07
Popularity	#11	#111

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 $6.25 for GPT-5 Chat, saving $0.25 (4% lower).
High-volume input processing	GPT-5 Chat	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	Gemini 3.5 Flash	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Gemma 4 31B (free) can replace Gemini 3.5 Flash when lower sample workload cost matters most: $0.
Gemma 4 26B A4B (free) 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.
Lyria 3 Pro 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 offers 2M context with $2.5 sample workload cost.
Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.

Popular competitors

DeepSeek V4 Flash · DeepSeek · #1
Hy3 preview · Tencent · #2
Claude Opus 4.7 · Anthropic · #3
Claude Sonnet 4.6 · Anthropic · #4

Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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Google catalog

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

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OpenAI catalog

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

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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 Chat

GPT-5 Chat is designed for advanced, natural, multimodal, and context-aware conversations for enterprise applications.