GPT-5.6 Sol vs. GPT-5.5: API Cost Comparison

On this API, GPT-5.6 Sol costs $1.75 / $10.5 per 1M tokens (in/out) and GPT-5.5 costs $1.75 / $10.5. GPT-5.6 Sol 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-5.6 Sol	GPT-5.5
Vendor	OpenAI	OpenAI
Input · per 1M tokens · Official list	$5	$5
Input · per 1M tokens · Your price	$1.75	$1.75
Output · per 1M tokens · Official list	$30	$30
Output · per 1M tokens · Your price	$10.5	$10.5
Discount vs. list	-65%	-65%
Context window	400K tokens	400K tokens
Max output tokens	128K tokens	128K 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-5.6 Sol

At official list: $110 per month
On this API: $38.5 per month

GPT-5.5

At official list: $110 per month
On this API: $38.5 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-5.6-sol"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "gpt-5.6-sol", "messages": [...]}'

model="gpt-5.5"

curl https://kktt.net/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -d '{"model": "gpt-5.5", "messages": [...]}'

FAQ

Which is cheaper, GPT-5.6 Sol or GPT-5.5?

On this API, GPT-5.6 Sol is cheaper: $1.75 in / $10.5 out per 1M tokens, versus $1.75 in / $10.5 out for GPT-5.5.

Can I use GPT-5.6 Sol and GPT-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-5.6 Sol and GPT-5.5 differ in context window?

GPT-5.6 Sol supports 400K of context with 128K max output; GPT-5.5 supports 400K with 128K max output.