Gemini 3.1 Pro Preview vs GPT-5.2-Codex

Gemini 3.1 Pro Preview at $2.30 in and $13.80 out and GPT-5.2-Codex at $2.01 in and $16.10 out — per million tokens, from the same wallet.

Gemini 3.1 Pro Preview

Google

2.3¢

for a client proposal

$2.30 in · $13.80 out / 1M

1.05M context · released 6 months ago

Full page →

GPT-5.2-Codex

OpenAI

2.3¢

for a client proposal

$2.01 in · $16.10 out / 1M

400K context · released 7 months ago

Full page →

Asking all both at once — identical prompt, identical context — costs about 4.5¢ for a typical client proposal.

At a glance

Cheapest input: GPT-5.2-Codex at $2.01 per million tokens.
Cheapest output: Gemini 3.1 Pro Preview at $13.80 per million tokens.
Largest context: Gemini 3.1 Pro Preview at 1.05M tokens — about 1,500 pages.

Cost per task

Estimated totals at the rates above. Solid bar is input, lighter bar is output.

Quick code fix

2K in · 500 out

Gemini 3.1 Pro Preview

1.1¢

GPT-5.2-Codex

1.2¢

Draft a client proposal from notes

5K in · 800 out

Gemini 3.1 Pro Preview

2.3¢

GPT-5.2-Codex

2.3¢

Context-heavy session (Alyph workspace)

155K in · 4K out

Gemini 3.1 Pro Preview

$0.41

GPT-5.2-Codex

$0.38

Analyze a 50-page legal contract

35K in · 1K out

Gemini 3.1 Pro Preview

$0.09

GPT-5.2-Codex

$0.09

Large architecture refactor

250K in · 3K out

Gemini 3.1 Pro Preview

$1.21

GPT-5.2-Codex

$0.55

Long-context rate applied at this input size.

Solid part of each bar is input tokens, the lighter part is output. Models that don’t fit a task are marked instead of priced.

Cost vs Token Amount

Drag the slider to adjust the split between input and output workload.

80% Input20% Output

Gemini 3.1 Pro Preview

GPT-5.2-Codex

Adjust the ratio slider to change how output tokens influence the final price for equivalent workloads.

Pricing

Gemini 3.1 Pro Preview

GPT-5.2-Codex

Input / 1M tokens

$2.30

$2.01

Output / 1M tokens

$13.80

$16.10

Cached input / 1M

$0.230

$0.201

Web search

1.6¢ / search

1.1¢ / search

Specs

Gemini 3.1 Pro Preview

GPT-5.2-Codex

Provider

Google

OpenAI

Released

6 months ago

7 months ago

Context window

1.05M

400K

Max output

66K

128K

Input

Audio, Files, Images, Text, and Video

Text and Images

Output

Text

Reasoning

Shows its thinking

Knowledge cutoff

—

Try it with real numbers

2K tokens in · 500 tokens out.

Gemini 3.1 Pro Preview

Google

1.1¢

for this task

40% input · 60% output

Full pricing →

GPT-5.2-Codex

OpenAI

1.2¢

for this task

33% input · 67% output

Full pricing →

All 2, same prompt and context: 2.4¢. That is the entire cost of the comparison.

Your $5 welcome credit covers about 212 of these.

Which should you pick?

For long documents, Gemini 3.1 Pro Preview has the largest context window here — 1.05M tokens.

On price, Gemini 3.1 Pro Preview is the cheapest of the two on a typical task, at about 2.3¢.

Or don’t pick. Send the identical prompt to all both, read the answers side by side, and keep the winner. How to run a fair bake-off →

Gemini 3.1 Pro Preview pricing →GPT-5.2-Codex pricing →Add Lyria 3 Clip Preview Add Grok 4.20

Questions, answered

Which is cheaper, Gemini 3.1 Pro Preview or GPT-5.2-Codex?

On a typical client proposal (5K tokens in, 800 out): Gemini 3.1 Pro Preview at 2.3¢; GPT-5.2-Codex at 2.3¢. Long prompts can change the order when long-context rates apply.

Which has the largest context window?

Gemini 3.1 Pro Preview — 1.05M tokens, about 1,500 pages.

Can I run Gemini 3.1 Pro Preview and GPT-5.2-Codex side by side on Alyph?

Yes — that is what Alyph is built for: the identical prompt with identical context to all 2, answers rendered side by side, billed from one wallet. This exact combination costs about 4.5¢ for a typical task.

Ask both at once

Identical prompt, identical context, answers side by side — about 4.5¢ for a typical client proposal. Free to start, with $5 of credit.