Gemini 3.5 Flash vs GPT-5
Google's newest Flash model goes head-to-head with OpenAI's flagship. GPT-5 is 17% cheaper on input, but Gemini packs 3.7x more context. A true mid-tier showdown.
Pricing data verified: Jun 2026
| Specification | Gemini 3.5 Flash (Google) | GPT-5 (OpenAI) |
|---|---|---|
| Input Price (per 1M tokens) | $1.50 | $1.25 |
| Output Price (per 1M tokens) | $9.00 | $10.00 |
| Context Window | 1M tokens | 272K tokens |
| Tier | Mid | Premium |
| Provider | OpenAI |
Calculate Your Exact Costs
Different pricing tiers, different strengths — see which is cheaper for your workload.
Other Models to Consider
Which Model for Which Use Case?
Long Document Processing
Gemini 3.5 Flash's 1M context window handles entire codebases, legal contracts, or research papers in a single request. GPT-5's 272K context may require chunking.
High-Input Classification
For workloads with heavy input tokens (document classification, sentiment analysis), GPT-5's 17% cheaper input pricing ($1.25 vs $1.50/M) adds up at scale.
Content Generation
Content generation is output-heavy. Gemini 3.5 Flash is 10% cheaper on output ($9.00 vs $10.00/M), making it the better choice for blog posts, marketing copy, and creative writing.
Function Calling & Agents
GPT-5 has mature function calling and the Assistants API for building AI agents. If you need tool use, OpenAI's ecosystem is more battle-tested.
Comparing Google and OpenAI?
APIpulse Pro lets you compare all 39 models, find the cheapest option for your exact usage, and save scenarios for your team.
Frequently Asked Questions
Is GPT-5 cheaper than Gemini 3.5 Flash?
On input tokens, yes — GPT-5 costs $1.25/M vs Gemini 3.5 Flash at $1.50/M (17% cheaper). On output tokens, Gemini is cheaper at $9.00/M vs GPT-5's $10.00/M (10% cheaper). Overall cost depends on your input/output ratio.
Which has a larger context window?
Gemini 3.5 Flash has a 1M token context window — 3.7x larger than GPT-5's 272K context. For long documents, codebases, or extended conversations, Gemini handles significantly more context in a single request.
When should I choose GPT-5?
Choose GPT-5 if you need OpenAI's ecosystem (function calling, Assistants API, GPT plugins), prefer OpenAI's reasoning quality, or have high-input/low-output workloads where GPT-5's cheaper input pricing matters most.
When should I choose Gemini 3.5 Flash?
Choose Gemini 3.5 Flash if you need a 1M context window for long documents, want Google Cloud/Vertex AI integration, have high-output workloads where Gemini's cheaper output matters, or need multimodal capabilities.