Head to head · October 2026

Claude Sonnet 5 vs GPT-6 Luna API pricing

GPT-6 Luna costs 24.6 times less per token at an 80/20 mix. Input costs 25.4x more on Claude Sonnet 5. Output costs 24.0x more on Claude Sonnet 5.

Anthropic

Claude Sonnet 5

Daily coding in Cursor, Cline and Claude Code.

Vendor: Anthropic
Type: Frontier
SayGM in / out: $1.78 / $8.89
OpenRouter in / out: $2.11 / $10.55
Blended, 80/20: $3.202
Per 100M tokens: $320
Output share of bill: 56%
SayGM vs OpenRouter: 16% lower

OpenAI

GPT-6 Luna

Chat products, summarisation, cheap tool calls.

Vendor: OpenAI
Type: Frontier
SayGM in / out: $0.07 / $0.37
OpenRouter in / out: $0.11 / $0.53
Blended, 80/20: $0.130
Per 100M tokens: $13
Output share of bill: 57%
SayGM vs OpenRouter: 33% lower

§ 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

Claude Sonnet 5 on SayGM
GPT-6 Luna on SayGM

Side project5M in · 1M out

$18

$0.72

Production app50M in · 15M out

$222

$9.05

High volume500M in · 100M out

$1,779

$72

Show data as a table

	Claude Sonnet 5 on SayGM	GPT-6 Luna on SayGM
Side project (5M in · 1M out)	$18	$0.72
Production app (50M in · 15M out)	$222	$9.05
High volume (500M in · 100M out)	$1,779	$72

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 GPT-6 Luna and escalate to Claude Sonnet 5 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
Claude Sonnet 5Anthropic	$1.78 / $8.89	$2.11 / $10.55	16% lower
GPT-6 LunaOpenAI	$0.07 / $0.37	$0.11 / $0.53	33% lower

Current SayGM rates

§ 04

Claude Sonnet 5 vs GPT-6 Luna questions

Which is cheaper, Claude Sonnet 5 or GPT-6 Luna?

GPT-6 Luna is about 24.6 times cheaper than Claude Sonnet 5 at an 80/20 input to output mix on SayGM, as of October 2026.

How much do Claude Sonnet 5 and GPT-6 Luna cost on OpenRouter?

Including the 5.5 percent top-up fee, Claude Sonnet 5 costs $2.11 input and $11 output per million tokens, and GPT-6 Luna costs $0.11 and $0.53.

Can I use Claude Sonnet 5 and GPT-6 Luna with one API key?

Yes. SayGM serves both through their native APIs on a single key, so simple tasks can go to GPT-6 Luna and hard ones to Claude Sonnet 5, or both can run in a cascade model.

§ 05