GPT-5.6 Luna vs GPT-5.6 Terra — Price, Context, and Capability Compared
GPT-5.6 Luna vs GPT-5.6 Terra: which should I use?
GPT-5.6 Terra costs 10.0× more per blended million tokens than GPT-5.6 Luna. GPT-5.6 Luna has the larger context window (1,000,000 tokens). Default to GPT-5.6 Luna unless you specifically need GPT-5.6 Terra's edge. Only GPT-5.6 Terra exposes an extended-thinking mode.
Price, speed, and task evidence
Task verdict
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Best fit | High-volume, latency-sensitive tasks like classification, extraction, and chat. | Everyday production workloads that need strong quality without Sol-tier pricing. |
| Reasoning mode | Unavailable | Available |
Effective workload cost
Modeled for Coding Agent: 20,000 input + 2,000 output tokens per task, 1 turn. This is a workload model, not a provider quote.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Coding Agent / task | $0.0064 (modeled) (winner) | $0.06 (modeled) |
| Input / output rate | $0.20 / $1.20 per M | $2.00 / $12.00 per M |
Speed
Only non-estimated benchmark results are shown as measured.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Measured throughput | 126 tokens/s (winner) | 78 tokens/s |
| Time to first token | 300 ms | 380 ms |
API compatibility
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| OpenAI SDK | Usable | Usable |
| Request shape | Canonical /chat/completions and /responses shape — every OpenAI-compatible provider on this site imitates it. | Canonical /chat/completions and /responses shape — every OpenAI-compatible provider on this site imitates it. |
| Streaming | SSE (OpenAI delta) | SSE (OpenAI delta) |
Privacy and retention
Provider policy and residency facts from the verified provider registry. A missing retention policy is not treated as a guarantee.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Provider says API data trains models | No | No |
| Published retention period | Unavailable | Unavailable |
| Data residency | US by default; EU data residency available on enterprise agreements | US by default; EU data residency available on enterprise agreements |
Migration effort
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Move GPT-5.6 Luna → GPT-5.6 Terra | drop-in; 0 breaking parameter differences | Target: GPT-5.6 Terra |
| Move GPT-5.6 Terra → GPT-5.6 Luna | Source: GPT-5.6 Terra | drop-in; 0 breaking parameter differences |
| Why | Same provider; only the model identifier changes. | Same provider; only the model identifier changes. |
Spec comparison
| GPT-5.6 Luna | GPT-5.6 Terra | |
|---|---|---|
| Price (input) | $0.20/M ✓ | $2.00/M |
| Price (output) | $1.20/M ✓ | $12.00/M |
| Blended price | $0.45/M ✓ | $4.50/M |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 64,000 tokens | 128,000 tokens ✓ |
| Modalities | text, vision | text, vision |
| Reasoning mode | No | Yes |
| Released | 2026-06 | 2026-06 |
| Speed | 126 t/s ✓ | 78 t/s |
Cost at scale (3:1 blended)
| Tokens / month | GPT-5.6 Luna | GPT-5.6 Terra | Delta |
|---|---|---|---|
| 1,000,000 | $0.45 | $4.50 | $4.05 (10.0×) |
| 10,000,000 | $4.50 | $45.00 | $40.50 (10.0×) |
| 100,000,000 | $45.00 | $450.00 | $405.00 (10.0×) |
Choose GPT-5.6 Luna if…
- ✓Cheapest current GPT-5.6 tier
- ✓Low latency for high-volume calls
- ✓1M context window and vision input
- ✓High-volume, latency-sensitive tasks like classification, extraction, and chat.
Choose GPT-5.6 Terra if…
- ✓Balanced cost-to-intelligence ratio
- ✓Reasoning mode available on demand
- ✓Same 1M context as Sol
- ✓Everyday production workloads that need strong quality without Sol-tier pricing.
Run this exact matchup right now
Send the same prompt to GPT-5.6 Luna and GPT-5.6 Terra side by side and see the outputs yourself.
Try GPT-5.6 Luna vs GPT-5.6 Terra FreeFAQ
Is GPT-5.6 Luna cheaper than GPT-5.6 Terra?
GPT-5.6 Luna is cheaper, at $0.45 per million blended tokens vs $4.50 for GPT-5.6 Terra.
Which has the bigger context window, GPT-5.6 Luna or GPT-5.6 Terra?
Both models support 1,000,000 tokens of context.
Can GPT-5.6 Luna replace GPT-5.6 Terra for coding?
Both are viable for coding. Cheapest current GPT-5.6 tier (GPT-5.6 Luna) vs Balanced cost-to-intelligence ratio (GPT-5.6 Terra) — pick based on which strength matters more for your workload.
Which is faster, GPT-5.6 Luna or GPT-5.6 Terra?
GPT-5.6 Luna is faster: 126 t/s vs 78 t/s, measured on our speed benchmarks.
Neither of these? See GPT-5.6 Luna alternatives or GPT-5.6 Terra alternatives.
Related
Pricing verified 2026-07-30. Specs verified 2026-08-08.