Gemini 2.5 Pro vs GPT-5.1-Codex

Gemini 2.5 Pro at $1.44 in and $11.50 out and GPT-5.1-Codex at $1.44 in and $11.50 out — per million tokens, from the same wallet.

Gemini 2.5 Pro

Google

1.6¢

for a client proposal

$1.44 in · $11.50 out / 1M

1.05M context · released June 2025

Full page →

GPT-5.1-Codex

OpenAI

1.6¢

for a client proposal

$1.44 in · $11.50 out / 1M

400K context · released November 2025

Full page →

Asking all both at once — identical prompt, identical context — costs about 3.3¢ for a typical client proposal.

At a glance

All 2 cost the same on input.
Largest context: Gemini 2.5 Pro 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 2.5 Pro

0.86¢

GPT-5.1-Codex

0.86¢

Draft a client proposal from notes

5K in · 800 out

Gemini 2.5 Pro

1.6¢

GPT-5.1-Codex

1.6¢

Context-heavy session (Alyph workspace)

155K in · 4K out

Gemini 2.5 Pro

$0.27

GPT-5.1-Codex

$0.27

Analyze a 50-page legal contract

35K in · 1K out

Gemini 2.5 Pro

$0.06

GPT-5.1-Codex

$0.06

Large architecture refactor

250K in · 3K out

Gemini 2.5 Pro

$0.77

GPT-5.1-Codex

$0.39

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 2.5 Pro

GPT-5.1-Codex

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

Pricing

Gemini 2.5 Pro

GPT-5.1-Codex

Input / 1M tokens

$1.44

Output / 1M tokens

$11.50

Cached input / 1M

$0.144

$0.149

Web search

1.6¢ / search

1.1¢ / search

Specs

Gemini 2.5 Pro

GPT-5.1-Codex

Provider

Google

OpenAI

Released

June 2025

November 2025

Context window

1.05M

400K

Max output

66K

128K

Input

Text, Images, Files, Audio, and Video

Text and Images

Output

Text

Reasoning

Shows its thinking

Knowledge cutoff

2025-01-31

—

Try it with real numbers

2K tokens in · 500 tokens out.

Gemini 2.5 Pro

Google

0.86¢

for this task

33% input · 67% output

Full pricing →

GPT-5.1-Codex

OpenAI

0.86¢

for this task

33% input · 67% output

Full pricing →

All 2, same prompt and context: 1.7¢. That is the entire cost of the comparison.

Your $5 welcome credit covers about 289 of these.

Which should you pick?

For long documents, Gemini 2.5 Pro has the largest context window here — 1.05M tokens.

On price they are identical: about 1.6¢ for a typical task each.

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 2.5 Pro pricing →GPT-5.1-Codex pricing →Add Lyria 3 Clip Preview Add Grok 4.20

Questions, answered

Which is cheaper, Gemini 2.5 Pro or GPT-5.1-Codex?

On a typical client proposal (5K tokens in, 800 out) they cost the same — about 1.6¢ each. Compare them on context and capabilities instead.

Which has the largest context window?

Gemini 2.5 Pro — 1.05M tokens, about 1,500 pages.

Can I run Gemini 2.5 Pro and GPT-5.1-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 3.3¢ for a typical task.

Ask both at once

Identical prompt, identical context, answers side by side — about 3.3¢ for a typical client proposal. Free to start, with $5 of credit.