Is Gemini 3.1 Pro or GPT-5.5 cheaper?

For a typical request (10,000 input + 2,000 output tokens), Gemini 3.1 Pro is cheaper — about 60% less, or roughly $6600 saved per 100,000 requests. Gemini 3.1 Pro runs $2/$12 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 3.1 Pro: 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 3.1 Pro vs GPT-5.5: pricing & cost comparison

On input tokens, Gemini 3.1 Pro is the cheaper of the two — 60% less per million ($2 vs $5). On output, Gemini 3.1 Pro is 60% cheaper ($12 vs $30) — and since output is usually the dominant cost driver, that gap matters more than it looks.

Side by side

	Gemini 3.1 Pro	GPT-5.5
Input / 1M tokens	$2	$5
Output / 1M tokens	$12	$30
Context window	1,000,000	1,050,000
Token-count accuracy	±3%	exact
Cost — 10,000 input + 2,000 output tokens	$0.044	$0.11

What a real request costs

Take a representative turn — 10,000 input + 2,000 output tokens. Gemini 3.1 Pro comes to $0.044, GPT-5.5 to $0.11. Across 100,000 requests that's a $6600 swing in favour of Gemini 3.1 Pro. To run the numbers on your actual prompt, paste it into the calculator and toggle Compare across all models.

Close call — decide on output cost

Gemini 3.1 Pro and GPT-5.5 are close enough on price that the tie-breakers matter more than the headline rate. Output tokens are usually the dominant cost driver, so weigh $12 vs $30 per 1M output first, then context window — GPT-5.5 carries the larger one at 1,050,000 tokens. They're different vendors, so factor in a small tokenizer calibration buffer on whichever side isn't exact.

See the full breakdown on the dedicated pages for Gemini 3.1 Pro and GPT-5.5.

FAQ

Is Gemini 3.1 Pro or GPT-5.5 cheaper?: For a typical request (10,000 input + 2,000 output tokens), Gemini 3.1 Pro is cheaper — about 60% less, or roughly $6600 saved per 100,000 requests. Gemini 3.1 Pro runs $2/$12 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 3.1 Pro: 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.