At 40 requests/user/day (totaling 120,000,000 queries/mo), running AI coding assistant on Gemini 3.1 Pro costs $4,204,800.00 / month ($42.048 / user / mo).
Total expected API invoice for 100,000 Active Users generating 120,000,000 queries.
Direct inference cost per MAU to model your SaaS pricing tiers and gross margins.
Savings generated by exploiting 60% cache hits on prompt context.
| Model | Provider | Monthly Spend (100,000 Active Users) | Cost / User / Mo | Annual Spend | Context Limit |
|---|---|---|---|---|---|
| Gemini 3.1 Pro (Current) | $4,204,800.00 | $42.048 | $50,457,600.00 | 2,000,000 | |
| GPT-5.6 Sol | openai | $10,512,000.00 | $105.12 | $126,144,000.00 | 1,050,000 |
| GPT-5.6 Cyber | openai | $26,280,000.00 | $262.80 | $315,360,000.00 | 1,050,000 |
| GPT-5.5 Standard | openai | $10,512,000.00 | $105.12 | $126,144,000.00 | 512,000 |
| GPT-5.5 Pro | openai | $63,072,000.00 | $630.72 | $756,864,000.00 | 512,000 |
| o3-pro (Frontier Reasoning) | openai | $32,448,000.00 | $324.48 | $389,376,000.00 | 1,000,000 |
At 40 queries per user/day with Gemini 3.1 Pro, the estimated cost is $42.048 per monthly active user (MAU). Total monthly bill for 100,000 Active Users is $4,204,800.00.
Assuming a 60% cache hit rate on repeated system and context tokens, prompt caching saves $1,555,200.00 per month ($18,662,400.00/year) on Gemini 3.1 Pro.
With a direct COGS of $42.048 per user/month on Gemini 3.1 Pro, charging at least $210.24 per user/month ensures an 80%+ software gross margin.