GPT-6.1 Terra vs. Claude Sonnet 5.5: API Cost Comparison

On this API, GPT-6.1 Terra costs $0.35 / $1.75 per 1M tokens (in/out) and Claude Sonnet 5.5 costs $1 / $5. GPT-6.1 Terra is the cheaper option, and both run on the same key — switching is a one-line model parameter change.

Get an API key All model prices

Per-token pricing

	GPT-6.1 Terra	Claude Sonnet 5.5
Vendor	OpenAI	Anthropic
Input · per 1M tokens · Official list	$1	$2
Input · per 1M tokens · Your price	$0.35	$1
Output · per 1M tokens · Official list	$5	$10
Output · per 1M tokens · Your price	$1.75	$5
Discount vs. list	-65%	-50%
Context window	400K tokens	200K tokens
Max output tokens	128K tokens	64K tokens

All prices in USD per 1M tokens.

What a real workload costs

Same request stream priced on both models — 10M input + 2M output tokens per month, a typical coding-agent load:

GPT-6.1 Terra

At official list: $20 per month
On this API: $7 per month

Claude Sonnet 5.5

At official list: $40 per month
On this API: $20 per month

Switching between them

Both models answer on the same endpoint. Keep your base URL and key; change only the model parameter to reroute a request:

model="gpt-6.1-terra"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "gpt-6.1-terra", "messages": [...]}'

model="claude-sonnet-5-5"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "claude-sonnet-5-5", "messages": [...]}'

FAQ

Which is cheaper, GPT-6.1 Terra or Claude Sonnet 5.5?

On this API, GPT-6.1 Terra is cheaper: $0.35 in / $1.75 out per 1M tokens, versus $1 in / $5 out for Claude Sonnet 5.5.

Can I use GPT-6.1 Terra and Claude Sonnet 5.5 with the same API key?

Yes. Both are callable with one key on the same base URL — switching between them is a one-line change of the model parameter, which makes A/B testing or fallback routing trivial.

Do GPT-6.1 Terra and Claude Sonnet 5.5 differ in context window?

GPT-6.1 Terra supports 400K of context with 128K max output; Claude Sonnet 5.5 supports 200K with 64K max output.