GPT-5.5 costs 49 to 92 percent more than its predecessor, depending on the input length

GPT-5.5's list price has doubled compared to GPT-5.4. Input tokens now cost $5 and output tokens $30 per million, up from $2.50 and $15. OpenAI says shorter responses should partially offset this, but a study by OpenRouter shows real-world costs still rose 49 to 92 percent.

For inputs over 10,000 tokens, responses are 19 to 34 percent shorter, easing costs somewhat. In the 2,000 to 10,000 token range, however, responses run 52 percent longer. For short inputs under 2,000 tokens, response length barely changes, nearly doubling effective costs. The data comes from OpenRouter's usage logs from April 2026.

Input length

Avg $/M tokens (5.4)

Avg $/M tokens (5.5)