GPT-5.6 Luna vs DeepSeek V4-Pro
OpenAI's GPT-5.6 Luna and DeepSeek's DeepSeek V4-Pro both target production language workloads, but they price and behave differently. Here is the side-by-side.
Pricing checked against provider documentation on . How we verify
The short answer
GPT-5.6 Luna is the cheaper option — roughly 2.2x less on a blended workload, and it suits high-volume work on a tight budget. DeepSeek V4-Pro justifies its premium when you need frontier-adjacent reasoning at open-weight prices.
OpenAI • GPT-5.6
$0.20 / $1.20
/ 1M tokens (input / output)
After an 80% price cut in July 2026, Luna became the value outlier among frontier-family models: it outperforms the previous generation's top-end Opus tier on coding evals while costing about a fiftieth of Fable 5 per input token. This is the model to route bulk traffic through in a tiered architecture.
DeepSeek • DeepSeek V4
$0.66 / $1.98
/ 1M tokens (input / output)
A 1.6T-parameter mixture-of-experts model with 49B active, released under MIT and callable through DeepSeek's own API with configurable reasoning effort. Since 16 August 2026 DeepSeek bills on a peak/off-peak schedule, so the hour you run a job changes the bill by exactly 2x — which makes it unusually well suited to scheduled batch work.
Input price
DeepSeek V4-Pro is 3.3x the price than GPT-5.6 Luna on input tokens.
Output price
DeepSeek V4-Pro is 65% more expensive than GPT-5.6 Luna on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | GPT-5.6 Luna | DeepSeek V4-Pro | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $0 | $1 | $1 |
| Moderate — 10M in / 2M out | $4 | $11 | $6 |
| Heavy — 100M in / 20M out | $44 | $106 | $62 |
Specification comparison
| Attribute | GPT-5.6 Luna | DeepSeek V4-Pro |
|---|---|---|
| Input (/ 1M tokens) | $0.20 | $0.66 |
| Output (/ 1M tokens) | $1.20 | $1.98 |
| Cached input | $0.02 | $0.02 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 131,072 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2026-03 |
| Relative latency | low | medium |
| Open weights | No | MIT |
| API model ID | gpt-5.6-luna | deepseek-v4-pro |
| Status | stable | stable |
GPT-5.6 Luna: Cut 80% from the $1/$6 launch price on 2026-07-30.
DeepSeek V4-Pro: Off-peak rate shown. Peak rates are exactly double ($1.32 input / $3.96 output) during 01:00–04:00 and 06:00–10:00 UTC, Monday to Friday. Cache hits cost roughly 3% of a cache miss.
Choose GPT-5.6 Luna if…
- Classification and content moderation
- High-frequency agent subtasks
- Bulk summarization
- Cost-sensitive chat features
Choose DeepSeek V4-Pro if…
- Overnight batch reasoning jobs
- Self-hosted deployments needing MIT terms
- Cost-sensitive coding agents
- Chinese-language workloads
Frequently asked
Is GPT-5.6 Luna or DeepSeek V4-Pro cheaper?
GPT-5.6 Luna is cheaper. On a blended 3:1 input-to-output workload it costs about 2.2x less than DeepSeek V4-Pro.
Which has the larger context window, GPT-5.6 Luna or DeepSeek V4-Pro?
GPT-5.6 Luna has the larger window at 1.05M tokens versus 1M.
Should I use GPT-5.6 Luna or DeepSeek V4-Pro?
Pick GPT-5.6 Luna for high-volume work on a tight budget. Pick DeepSeek V4-Pro for frontier-adjacent reasoning at open-weight prices. If cost dominates the decision, GPT-5.6 Luna wins; if you need the capability ceiling, benchmark both on your own evals before committing.