DeepSeek-V4.1-Flash vs GPT-5.1

API pricing, benchmark indices and specs — updated 19 October 2026.

deepseek-ai · A · Open weights

Params

763.2 B

Context

—

30d

1.5 M

mit · commercial OK

openai · B · API-only

Input / 1M

$1.25

Output / 1M

$10.00

AA index

24.7

proprietary · 400K context

Specification comparison

Differences are highlighted; identical values are muted.

Specification	DeepSeek-V4.1-Flash	GPT-5.1
Deployment	Open weights · also via API	API-only (closed weights)
Parameters	763.2 B	n/a — API-only
Architecture	DeepseekV41ForCausalLM	n/a — API-only
Context length	1,048,576	400,000
Licence	mit	Proprietary
Commercial use	Allowed	Per API terms
Languages	—	n/a — API-only
Downloads 30d	1,478,503	n/a — API-only
Downloads all time	2.1 M	n/a — API-only
Quantizations on the Hub	SAFETENSORS	n/a — API-only
Gated	No	n/a — API-only
First seen on the Hub	2026-09-10	n/a — API-only
API input price / 1M tokens	$0.02	$1.25
API output price / 1M tokens	$1.00	$10.00
Est. cost per 1M input + 1M output tokens	$1.02	$11.25
Cached input / 1M tokens	$0.015	$0.13
AA Intelligence Index	24.7	24.7
AA Coding Index	—	49.4
AA Agentic Index	—	—
Max output tokens	943,718	128,000
API providers	33	2
Tool calling	Yes	Yes
Reasoning mode	Yes	Yes

Estimated cost of 1M input + 1M output tokens via OpenRouter

DeepSeek-V4.1-Flash $1.02

GPT-5.1 $11.25

DeepSeek-V4.1-Flash is 11.0× cheaper at list price.

On RTX 4090 · 24 GB · 8K context unless noted

DeepSeek-V4.1-Flash · fp16 676.3 GB / 24 GB

❌ Won’t fit