GPT-5.6 Luna vs DeepSeek — cheap tier, different winners

DeepSeek V4 Flash still wins many raw $/token spreadsheets at about $0.14 / $0.28 per 1M. GPT-5.6 Luna sits at $0.20 / $1.20 after the −80% cut. Luna is not the cheapest row — it is the current-gen OpenAI cheap tier for agents that need that ecosystem.

List-price snapshot

Verify DeepSeek’s current API page and OpenAI pricing before you lock a budget. Luna’s output rate is the gap that shows up in chatty agent loops.

Worked cost sketch (10M in + 5M out)

• DeepSeek V4 Flash: ≈ $2.80
• GPT-5.6 Luna: ≈ $8.00
• DeepSeek V4 Pro: ≈ $8.70

Flash wins the spreadsheet. Luna and Pro land in a similar band on this mix — pick Luna for OpenAI tools/vision; pick Flash for pure volume.

Capability tradeoffs that change the pick

• Vision / multimodal: Luna accepts image input on common OpenAI configs; DeepSeek Flash is often text-first in hosted setups.
• Tool APIs: Luna inherits GPT-5.6 Responses tooling; DeepSeek stays OpenAI-compatible chat with its own thinking modes.
• Vendor posture: some buyers need a US frontier vendor on the invoice; others optimize purely for $/token.
• Hosted product proof: CloudAxis Auto Mode standardized on Luna (not because it is the cheapest catalog row).

Longer comparison: Luna vs DeepSeek on CloudAxis.

FAQ

Is GPT-5.6 Luna cheaper than DeepSeek V4 Flash?

Usually not. Flash list rates around $0.14/$0.28 undercut Luna’s $0.20/$1.20, especially on output. Pick Luna for OpenAI-shaped capability, not the absolute floor.

Why would anyone choose Luna over Flash?

Vision, GPT-5.6 tool surfaces, US-vendor procurement, or hosted products that standardize on Luna for outcome consistency.

Where do I sort cheapest output live?

Open /tools/ai-model-pricing and sort by output USD per 1M ascending, then filter DeepSeek and OpenAI rows side by side.

Related

GPT-5.6 family pricing · Luna vs Haiku · Cheapest LLM API · Cost calculator.