Free-Tier Runway Calculator
Compounds your usage growth against an allowance and says how many days are left, for a one-off credit or one that resets.
Then you start paying. The first 30 days after that cost $63.21.
- Usage on day 1
- $1.20
- Usage on day 30
- $1.47
- Used in the first 30 days
- $39.90
- Share of the allowance gone by day 30
- 39.9%
- Day the allowance runs out
- day 66
- Spend in the 30 days after it runs out
- $63.21
- Usage in days 336–365, one year out
- $412.14
- What that year-out month costs
- $412.14
Runway is a planning number, not a promise
A free tier ends in one of two ways: you exhaust a one-off credit, or you overrun an allowance that refills. The arithmetic differs. A one-off credit is a cumulative sum against a fixed total, so growth compounds against you twice — you use more per day AND you have used more already. A resetting allowance is a race inside each window, and what matters is the day of the month you cross it, because everything after that day is billed at full price.
The compounding is the part worth staring at. Five percent a week does not sound like much and is a little over 12× a year. A credit that looks like six months of runway at today's usage is often two or three months at a realistic growth rate, and the difference is entirely in a number most people guess at rather than measure. Take the weekly figure from your own last eight weeks rather than from a plan.
What this does not model, and what usually bites first: rate limits. Most free tiers cap requests and tokens per minute as well as per month, and a burst hits those long before the monthly total is anywhere near gone. Nor does it know about the terms attached — some free access is priced in data rather than dollars, and a free tier whose terms allow training on your prompts is not free for every workload. Work out the runway, then read the terms; the runway tells you when to have the conversation, not whether the tier is a good idea.