DeepSeek V4 Flash 0731 vs GPT-5 Nano

DeepSeek V4 Flash 0731 at $0.103 in and $0.207 out and GPT-5 Nano at $0.058 in and $0.460 out — per million tokens, from the same wallet.

DeepSeek V4 Flash 0731

DeepSeek

0.07¢

for a client proposal

$0.103 in · $0.207 out / 1M

1.05M context · released 3 months ago

Full page →

GPT-5 Nano

OpenAI

0.07¢

for a client proposal

$0.058 in · $0.460 out / 1M

400K context · released August 2025

Full page →

Asking all both at once — identical prompt, identical context — costs about 0.13¢ for a typical client proposal.

At a glance

Cheapest input: GPT-5 Nano at $0.058 per million tokens.
Cheapest output: DeepSeek V4 Flash 0731 at $0.207 per million tokens.
Largest context: DeepSeek V4 Flash 0731 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

DeepSeek V4 Flash 0731

0.03¢

GPT-5 Nano

0.03¢

Draft a client proposal from notes

5K in · 800 out

DeepSeek V4 Flash 0731

0.07¢

GPT-5 Nano

0.07¢

Context-heavy session (Alyph workspace)

155K in · 4K out

DeepSeek V4 Flash 0731

1.7¢

GPT-5 Nano

1.1¢

Analyze a 50-page legal contract

35K in · 1K out

DeepSeek V4 Flash 0731

0.38¢

GPT-5 Nano

0.25¢

Large architecture refactor

250K in · 3K out

DeepSeek V4 Flash 0731

2.6¢

GPT-5 Nano

1.6¢

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

DeepSeek V4 Flash 0731

GPT-5 Nano

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

Pricing

DeepSeek V4 Flash 0731

GPT-5 Nano

Input / 1M tokens

$0.103

$0.058

Output / 1M tokens

$0.207

$0.460

Cached input / 1M

$0.021

$0.0057

Web search

—

1.1¢ / search

Specs

DeepSeek V4 Flash 0731

GPT-5 Nano

Provider

DeepSeek

OpenAI

Released

3 months ago

August 2025

Context window

1.05M

400K

Max output

384K

128K

Input

Text

Text, Images, and Files

Output

Text

Reasoning

Shows its thinking

Knowledge cutoff

—

2024-05-31

Try it with real numbers

2K tokens in · 500 tokens out.

DeepSeek V4 Flash 0731

DeepSeek

0.03¢

for this task

67% input · 33% output

Full pricing →

GPT-5 Nano

OpenAI

0.03¢

for this task

33% input · 67% output

Full pricing →

All 2, same prompt and context: 0.07¢. That is the entire cost of the comparison.

Your $5 welcome credit covers about 7,627 of these.

Which should you pick?

For long documents, DeepSeek V4 Flash 0731 has the largest context window here — 1.05M tokens.

On price, GPT-5 Nano is the cheapest of the two on a typical task, at about 0.07¢.

For images or files, GPT-5 Nano can read them directly; DeepSeek V4 Flash 0731 is text-only.

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 →

DeepSeek V4 Flash 0731 pricing →GPT-5 Nano pricing →Add Lyria 3 Clip Preview Add Grok 4.20

Questions, answered

Which is cheaper, DeepSeek V4 Flash 0731 or GPT-5 Nano?

On a typical client proposal (5K tokens in, 800 out): GPT-5 Nano at 0.07¢; DeepSeek V4 Flash 0731 at 0.07¢. Long prompts can change the order when long-context rates apply.

Which has the largest context window?

DeepSeek V4 Flash 0731 — 1.05M tokens, about 1,500 pages.

Can I run DeepSeek V4 Flash 0731 and GPT-5 Nano 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 0.13¢ for a typical task.

Ask both at once

Identical prompt, identical context, answers side by side — about 0.13¢ for a typical client proposal. Free to start, with $5 of credit.