Token Generation Time Calculator
For positive output length, estimated time equals first-token latency plus the remaining token count divided by the generation rate. Zero requested tokens gives zero modeled generation time.
Formula & method
If tokens > 0: seconds = first-token ms ÷ 1,000 + (tokens − 1) ÷ subsequent tokens/s.Worked example
| Input | Value |
|---|---|
| Output tokens | 501 |
| Rate after the first token | 50 tokens/s |
| Time to first token | 800 ms |
| Result | Value |
|---|---|
| Modeled generation duration | 10.8 s |
| Modeled generation duration | 0.18 min |
Compare scenarios
The first input changes while the other example inputs stay fixed. These are arithmetic scenarios, not forecasts.
| Compare scenarios | Output tokens | Modeled generation duration | Modeled generation duration |
|---|---|---|---|
| −19.96% | 401 | 8.8 s | 0.1466666667 min |
| Example | 501 | 10.8 s | 0.18 min |
| +19.96% | 601 | 12.8 s | 0.2133333333 min |
Assumptions & limits
A constant token rate is a simplifying assumption. Prefill, queueing, hidden reasoning, tool calls, network delivery and provider load can change observed latency. Enter a measured rate for comparable requests; no model speed is promised.
Displayed results are rounded. Calculations use unrounded JavaScript numbers; small floating-point differences are possible.
Works in your browser
The interactive tool runs in a sandbox with network access blocked. ClearByte and the advertising scripts cannot read values inside it. Browser extensions and a compromised device remain outside this protection.
Sources & definitions
Method checked:
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