GPT-5.6 Terra vs Gemini 3.1 Flash-Lite
OpenAI's GPT-5.6 Terra and Google's Gemini 3.1 Flash-Lite 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
Gemini 3.1 Flash-Lite is the cheaper option — roughly 8.0x less on a blended workload, and it suits ultra-cheap high-volume tasks. GPT-5.6 Terra justifies its premium when you need balanced production workloads. Only GPT-5.6 Terra does native reasoning, which matters for multi-step tasks but adds billable thinking tokens.
OpenAI • GPT-5.6
$2.00 / $12.00
/ 1M tokens (input / output)
The everyday tier of the GPT-5.6 family, roughly corresponding to the old 'mini' slot but benchmarking above the previous generation's flagship. For most application backends this is the default worth trying before reaching for Sol, since it clears Claude Fable 5 on several evals at a fraction of the cost.
Google • Gemini 3.1
$0.25 / $1.50
/ 1M tokens (input / output)
Google's efficiency tier and a long-term stable target, priced for workloads measured in millions of calls rather than thousands. It gives up the deeper reasoning of 3.5 Flash, so it suits mechanical tasks — classification, extraction, moderation — where a million tokens of context still helps but chain-of-thought does not.
Input price
Gemini 3.1 Flash-Lite is 88% cheaper than GPT-5.6 Terra on input tokens.
Output price
Gemini 3.1 Flash-Lite is 88% cheaper than GPT-5.6 Terra 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 Terra | Gemini 3.1 Flash-Lite | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $4 | $1 | $4 |
| Moderate — 10M in / 2M out | $44 | $6 | $39 |
| Heavy — 100M in / 20M out | $440 | $55 | $385 |
Specification comparison
| Attribute | GPT-5.6 Terra | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input (/ 1M tokens) | $2.00 | $0.25 |
| Output (/ 1M tokens) | $12.00 | $1.50 |
| Cached input | $0.20 | — |
| Context window | 1,048,576 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Native reasoning | Yes | No |
| Knowledge cutoff | 2026-02 | 2025-01 |
| Relative latency | medium | low |
| Open weights | No | No |
| API model ID | gpt-5.6-terra | gemini-3.1-flash-lite |
| Status | stable | stable |
GPT-5.6 Terra: Cut 20% from the $2.50/$15 launch price on 2026-07-30.
Choose GPT-5.6 Terra if…
- Customer support and chat backends
- RAG and document processing pipelines
- Mid-complexity coding tasks
- Tool-calling agents at scale
Choose Gemini 3.1 Flash-Lite if…
- Content moderation at volume
- Classification and routing
- Lightweight summarization
- Cheap long-context retrieval
Frequently asked
Is GPT-5.6 Terra or Gemini 3.1 Flash-Lite cheaper?
Gemini 3.1 Flash-Lite is cheaper. On a blended 3:1 input-to-output workload it costs about 8.0x less than GPT-5.6 Terra.
Which has the larger context window, GPT-5.6 Terra or Gemini 3.1 Flash-Lite?
Both accept up to 1.05M tokens, so context is not a differentiator here.
Should I use GPT-5.6 Terra or Gemini 3.1 Flash-Lite?
Pick GPT-5.6 Terra for balanced production workloads. Pick Gemini 3.1 Flash-Lite for ultra-cheap high-volume tasks. If cost dominates the decision, Gemini 3.1 Flash-Lite wins; if you need the capability ceiling, benchmark both on your own evals before committing.