Is Gemini 2.5 Flash or GPT-5.5 cheaper?

For a typical request (10,000 input + 2,000 output tokens), Gemini 2.5 Flash is cheaper — about 93% less, or roughly $10200 saved per 100,000 requests. Gemini 2.5 Flash runs $0.3/$2.5 per 1M input/output tokens; GPT-5.5 runs $5/$30.

Which has the larger context window?

GPT-5.5, at 1,050,000 tokens versus 1,000,000.

How accurate are these token counts?

Gemini 2.5 Flash: Approximated with o200k_base; drift typically ~3% on English and code. GPT-5.5: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.

Gemini 2.5 Flash vs GPT-5.5: pricing & cost comparison

On input tokens, Gemini 2.5 Flash is the cheaper of the two — 94% less per million ($0.3 vs $5). On output, Gemini 2.5 Flash is 92% cheaper ($2.5 vs $30) — and since output is usually the dominant cost driver, that gap matters more than it looks.

Side by side

	Gemini 2.5 Flash	GPT-5.5
Input / 1M tokens	$0.3	$5
Output / 1M tokens	$2.5	$30
Context window	1,000,000	1,050,000
Token-count accuracy	±3%	exact
Cost — 10,000 input + 2,000 output tokens	$0.008	$0.11

What a real request costs

Take a representative turn — 10,000 input + 2,000 output tokens. Gemini 2.5 Flash comes to $0.008, GPT-5.5 to $0.11. Across 100,000 requests that's a $10200 swing in favour of Gemini 2.5 Flash. To run the numbers on your actual prompt, paste it into the calculator and toggle Compare across all models.

Different leagues

These two sit in different price tiers — GPT-5.5 runs roughly 14× the per-request cost of Gemini 2.5 Flash on the worked example — so they rarely compete for the same job. Reach for Gemini 2.5 Flash on high-volume, latency-sensitive work (classification, extraction, routing) and GPT-5.5 only where the harder reasoning earns its price. They're different vendors, so expect a different API and tokenizer: the OpenAI side counts exactly; the other lands within a few percent — budget a small calibration buffer when you switch.

See the full breakdown on the dedicated pages for Gemini 2.5 Flash and GPT-5.5.

FAQ

Is Gemini 2.5 Flash or GPT-5.5 cheaper?: For a typical request (10,000 input + 2,000 output tokens), Gemini 2.5 Flash is cheaper — about 93% less, or roughly $10200 saved per 100,000 requests. Gemini 2.5 Flash runs $0.3/$2.5 per 1M input/output tokens; GPT-5.5 runs $5/$30.
Which has the larger context window?: GPT-5.5, at 1,050,000 tokens versus 1,000,000.
How accurate are these token counts?: Gemini 2.5 Flash: Approximated with o200k_base; drift typically ~3% on English and code. GPT-5.5: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.

Both prices are computed from tokenmath's verified pricing table. Rates sourced from ai.google.dev and developers.openai.com, verified 2026-07-06. Vendor pricing changes often — confirm before you commit.