One chat reply3,000 tokens in, 500 outGPT 5.6 Terra costs 2.2× as much as GPT-6.1 Terra
$0.0055
$0.01
Summarise a 100-page report50,000 tokens in, 1,500 out, one requestGPT 5.6 Terra costs 2.1× as much as GPT-6.1 Terra
$0.06
$0.12
1,000 classification calls500 tokens in, 20 out, per call
$0.60
$1.24
Coding-agent session2M tokens in across ~60 turns, 60,000 out, no cache
$2.30
$4.72
Same session, cached85% of input read from the prompt cache, the rest written to itGPT 5.6 Terra costs 2.4× as much as GPT-6.1 Terra
$0.76
$1.81
At listed rates. Token counts are typical sizes, not measurements.
GPT-6.1 Terra pricing notes
Requests over 272K input tokens bill the entire request at 2x the input and cache rates and 1.5x the output rate; the listed price is the short-context rate.
Cache hits bill at $0.05 per 1M tokens; cache writes cost $1.25 (30-minute) or $2.50 (12-hour).
GPT 5.6 Terra pricing notes
Once a request passes 272K input tokens, the whole request bills at 2x input and cache rates and 1.5x output; the listed price is the standard rate.
Cache writes bill at $2.50 per 1M tokens (1.25x input); cache reads at $0.20 per 1M (0.1x input).
OpenAI's GPT-6.1 Terra is a fast, efficient model for visual reasoning, precise computer use and natural writing. At $1 / $5 it costs half of GPT-6.1 Sol and sits above GPT-6 Luna; it replaces GPT-5.6 Terra.
Pick it if
your prompts mix text and images and you want half of GPT-6.1 Sol's token price
you resend long prompts; cache hits bill at 5% of input
you want reasoning switched off entirely; Terra accepts reasoning effort none
Skip it if
GPT-6 Luna at $0.10 / $0.50 covers your workload
your prompts often pass 272K input tokens; the whole request then bills higher
The middle tier of OpenAI's GPT-5.6 family (Sol, Terra, Luna), which OpenAI positions for workloads that balance intelligence and cost. Sol and Luna are retired here; GPT-6.1 Sol matches its input price with cheaper output.
Pick it if
you want the tier OpenAI called GPT-5.5-competitive at 2x lower cost
your prompts repeat: cached input bills at $0.20 per million
you need image input and up to 128K output tokens
Skip it if
output dominates your bill: GPT-6.1 Sol charges $10 versus $12
prompts routinely pass 272K tokens, where every rate in the request rises
FAQ
Which is cheaper, GPT-6.1 Terra or GPT 5.6 Terra?
GPT-6.1 Terra lists lower input and output prices. On a coding-agent session (2M tokens in, 60,000 out) GPT-6.1 Terra costs $2.30 and GPT 5.6 Terra $4.72.
Can I switch between GPT-6.1 Terra and GPT 5.6 Terra mid-task?
Yes. In an Octomind session, /model octohub:gpt-6.1-terra and /model octohub:gpt-5.6-terra switch models without losing the conversation, so you can draft on one and review on the other.
Try either model
Switch between models inside the same Octomind session.