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GPT-5.6 Terra API Pricing & Cost Calculator

By TechCompare · Updated · How we check

Terra is the GPT-5.6 default for production. Stronger reasoning than Gemini 3.6 Flash at a higher list price, and the 90% cache discount keeps long-context loops cheap.

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Cost Comparison

Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices come live from OpenRouter at each maker's own price where it's listed. Temporary deals are left out.

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GPT-5.6 Terra is the middle tier of OpenAI's 5.6 lineup, between GPT-5.6 Sol (deep reasoning) and GPT-5.6 Luna (the lowest priced tier), and it's aimed at high-volume production workloads.

OpenAI: GPT-5.6 Terra

OpenAI's own price

Input
$2
Output
$12
Cached
$0.20

per 1M tokens

Batch availableFlex available

Price checked 2026-11-12

How this is calculated

GPT-5.6 Terra is priced at $2.00 per million input tokens and $12.00 per million output tokens at OpenAI's published list price, with a prompt caching discount of 90% ($0.20 per million). That puts it 2x below GPT-5.6 Sol on input and 10x above GPT-5.6 Luna on input. OpenAI's 50% batch discount applies via the Batch API ($1.00 per million inputs, $6.00 per million outputs).

Verdict

Make Terra the default for general production traffic. Sol's input rate is 2x Terra's and Terra's is 10x Luna's.

GPT-5.6 Terra lands at $2/M input and $12/M output, with the 90% cache discount dropping input to $0.20/M and the 50% batch discount (via OpenAI's Batch API) cutting the rates to $1/M input and $6/M output.

The cache discount carries the long-context case: an agentic loop with a stable 100K system prompt costs $0.02 per call in input at the cached rate, so you can keep Terra on for the loop instead of cascading down to a cheaper model.

More API Standalones scenarios

GPT-5.6 Terra vs Gemini 3.6 Flash
Two mid-tier workhorses with different modality mixes. Compare list prices, caching, and fit.
View details
GPT-5.6 Terra vs GPT-5.6 Sol
Two members of OpenAI's 2026 lineup. Compare token rates and which one your workload needs.
View details
GPT-6.1 Terra vs GPT-5.6 Terra
Work out what moving from the older Terra to the new one does to the bill, and when the switch pays back.
View details

Related guides

GPT-6.1 Terra API pricing
See the rates for the mid-tier GPT-6.1 model.
View guide
GPT-6.1 Terra vs GPT-5.6 Terra
Check what moving to the newer Terra does to your bill.
View guide
Context window explained
How a model context window caps prompt size.
View guide
BPE tokenization explained
How tokenizers chunk text into the units VRAM serves.
View guide

Frequently asked questions

Why pick GPT-5.6 Terra over GPT-5.6 Luna?
Terra ($2/$12 list price) is 10x more expensive than Luna ($0.20/$1.20 list price) on input and 10x on output, but produces meaningfully stronger reasoning. Pick Terra when quality matters and reserve Luna for high-volume classification, extraction, or simple completions.
How much does GPT-5.6 Terra cost per million output tokens?
GPT-5.6 Terra charges $12.00 per million output tokens at standard pricing. Through the Batch API, that drops to $6.00 per million. The 90% prompt caching discount brings cached input to $0.20 per million, which helps most when everyday production workloads reuse a stable prompt.
Why pick GPT-5.6 Terra over GPT-5.6 Sol?
Cost and most production workloads. Terra at $2/$12 is 2x cheaper than Sol's $4/$20 on input and 1.7x cheaper on output. Sol's premium only earns its keep on hardest-tier reasoning: deep math, multi-step planning, complex code synthesis. For chat, RAG, content generation, and classification, Terra is the right default.

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