GPT-5.5 Pro vs o1-pro

GPT-5.5 Pro at $34.50 in and $207.00 out and o1-pro at $172.50 in and $690.00 out — per million tokens, from the same wallet.

GPT-5.5 Pro

OpenAI

$0.34

for a client proposal

$34.50 in · $207.00 out / 1M

1.05M context · released 4 months ago

Full page →

o1-pro

OpenAI

$1.41

for a client proposal

$172.50 in · $690.00 out / 1M

200K context · released March 2025

Full page →

Asking all both at once — identical prompt, identical context — costs about $1.75 for a typical client proposal.

At a glance

Cheapest input: GPT-5.5 Pro at $34.50 per million tokens.
Cheapest output: GPT-5.5 Pro at $207.00 per million tokens.
Largest context: GPT-5.5 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

GPT-5.5 Pro

$0.17

o1-pro

$0.69

Draft a client proposal from notes

5K in · 800 out

GPT-5.5 Pro

$0.34

o1-pro

$1.41

Context-heavy session (Alyph workspace)

155K in · 4K out

GPT-5.5 Pro

$6.18

o1-pro

$29.50

Analyze a 50-page legal contract

35K in · 1K out

GPT-5.5 Pro

$1.41

o1-pro

$6.73

Large architecture refactor

250K in · 3K out

GPT-5.5 Pro

$9.25

o1-pro

needs 250K ctx

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

GPT-5.5 Pro

o1-pro

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

Pricing

GPT-5.5 Pro

o1-pro

Input / 1M tokens

$34.50

$172.50

Output / 1M tokens

$207.00

$690.00

Web search

1.1¢ / search

Specs

GPT-5.5 Pro

o1-pro

Provider

OpenAI

Released

4 months ago

March 2025

Context window

1.05M

200K

Max output

128K

100K

Input

Files, Images, and Text

Text, Images, and Files

Output

Text

Reasoning

Shows its thinking

Knowledge cutoff

2025-12-01

2023-10-31

Try it with real numbers

2K tokens in · 500 tokens out.

GPT-5.5 Pro

OpenAI

$0.17

for this task

40% input · 60% output

Full pricing →

o1-pro

OpenAI

$0.69

for this task

50% input · 50% output

Full pricing →

All 2, same prompt and context: $0.86. That is the entire cost of the comparison.

Your $5 welcome credit covers about 5 of these.

Which should you pick?

For long documents, GPT-5.5 Pro has the largest context window here — 1.05M tokens.

On price, GPT-5.5 Pro is the cheapest of the two on a typical task, at about $0.34.

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 →

GPT-5.5 Pro pricing →o1-pro pricing →Add Lyria 3 Clip Preview Add Grok 4.20

Questions, answered

Which is cheaper, GPT-5.5 Pro or o1-pro?

On a typical client proposal (5K tokens in, 800 out): GPT-5.5 Pro at $0.34; o1-pro at $1.41. Long prompts can change the order when long-context rates apply.

Which has the largest context window?

GPT-5.5 Pro — 1.05M tokens, about 1,500 pages.

Can I run GPT-5.5 Pro and o1-pro 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 $1.75 for a typical task.

Ask both at once

Identical prompt, identical context, answers side by side — about $1.75 for a typical client proposal. Free to start, with $5 of credit.