Head to head · October 2026

GPT-5.6 Luna vs DeepSeek V4.1 Flash API pricing

DeepSeek V4.1 Flash costs 1.0 times less per token at an 80/20 mix. Input costs 1.2x more on DeepSeek V4.1 Flash. Output costs 1.2x more on GPT-5.6 Luna.

OpenAI

GPT-5.6 Luna

Chat products, summarisation, cheap tool calls.

Vendor: OpenAI
Type: Frontier
SayGM in / out: $0.15 / $0.89
OpenRouter in / out: $0.21 / $1.27
Blended, 80/20: $0.298
Per 100M tokens: $30
Output share of bill: 60%
SayGM vs OpenRouter: 29% lower

DeepSeek

DeepSeek V4.1 Flash

Bulk generation, cheap open-weight inference.

Vendor: DeepSeek
Type: Open weight, TEE variant available
SayGM in / out: $0.18 / $0.72
OpenRouter in / out: $0.03 / $0.53
Blended, 80/20: $0.288
Per 100M tokens: $29
Output share of bill: 50%
SayGM vs OpenRouter: 122% higher

§ 01

Monthly bill at three usage levels

Both models on SayGM. The bars show how the price ratio turns into dollars as volume grows.

Fig. 1Monthly bill at three usage levels

GPT-5.6 Luna on SayGM
DeepSeek V4.1 Flash on SayGM

Side project5M in · 1M out

$1.64

$1.62

Production app50M in · 15M out

$21

$20

High volume500M in · 100M out

$164

$162

Show data as a table

	GPT-5.6 Luna on SayGM	DeepSeek V4.1 Flash on SayGM
Side project (5M in · 1M out)	$1.64	$1.62
Production app (50M in · 15M out)	$21	$20
High volume (500M in · 100M out)	$164	$162

Usage is millions of input and output tokens per month. No caching discount applied. Source: published rate cards, October 2026 snapshot. Current prices on saygm.com.

§ 02

Verdict

A common pattern is to send routine requests to DeepSeek V4.1 Flash and escalate to GPT-5.6 Luna on failure or low confidence. On one key, that is a model name change per request rather than a second provider account.

§ 03

Per-token prices

OpenRouter figures include its 5.5% top-up fee.

USD per million tokens, input and output. OpenRouter includes its 5.5% top-up fee. Snapshot from October 2026.
Model	SayGMin / out	OpenRouterin / out, fee incl.	SayGM vs OpenRouter80/20 blend
GPT-5.6 LunaOpenAI	$0.15 / $0.89	$0.21 / $1.27	29% lower
DeepSeek V4.1 FlashDeepSeek · TEE variant	$0.18 / $0.72	$0.03 / $0.53Cheapest provider	122% higher

Current SayGM rates

§ 04

GPT-5.6 Luna vs DeepSeek V4.1 Flash questions

Which is cheaper, GPT-5.6 Luna or DeepSeek V4.1 Flash?

DeepSeek V4.1 Flash is about 1.0 times cheaper than GPT-5.6 Luna at an 80/20 input to output mix on SayGM, as of October 2026.

How much do GPT-5.6 Luna and DeepSeek V4.1 Flash cost on OpenRouter?

Including the 5.5 percent top-up fee, GPT-5.6 Luna costs $0.21 input and $1.27 output per million tokens, and DeepSeek V4.1 Flash costs $0.03 and $0.53.

Can I use GPT-5.6 Luna and DeepSeek V4.1 Flash with one API key?

Yes. SayGM serves both through their native APIs on a single key, so simple tasks can go to DeepSeek V4.1 Flash and hard ones to GPT-5.6 Luna, or both can run in a cascade model.

§ 05