GPT-5.5 Price Increase: What It Actually Costs
For prompts above 10K tokens, GPT-5.5 produces 19-34% fewer tokens. For shorter prompts, the pattern reverses: under 2K tokens completions are roughly the same length, and in the 2K-10K range they are 52% longer.
Actual Cost Impact
Using billed costs from requests in the switcher cohort, we calculated the average cost per million OpenRouter tokens. This normalizes for prompt length, allowing a direct comparison of cost efficiency.
Our analysis shows that GPT-5.5 actual costs increased 49% to 92%. Longer prompts, over 10k tokens, saw costs offset by shorter completions. Shorter prompts, under 10k, experience a higher cost increase where completions did not get shorter.
Methodology
- Source: OpenRouter's request logs
- Cohort: Users whose top model by request count was GPT-5.4, who then switched to GPT-5.5 as their top model
- Sample size: Text-only, non-cancelled requests split across 5.4 and 5.5
- Windows: GPT-5.4: April 21-23, 2026 (pre-launch); GPT-5.5: April 25-28, 2026 (post-launch, launch day excluded)
- Normalization: Cost per million OpenRouter tokens, bucketed by prompt token count. OpenRouter counts tokens independently from OpenAI, providing a consistent baseline across model versions.
- Controls: Excluded media (images, files, audio, video), cancelled requests, and zero-token requests