THE NUMBERS, EXPLAINED
How to use this calculator.
Conceptual continuous-time watermark before an event is maximum timestamp of previous arrivals minus allowed lateness; engine-specific millisecond offsets are not modeled. An event is late only if below that watermark; equality is accepted.
Start with your inputs
Enter event timestamps in arrival order (seconds), allowed lateness (seconds). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Event timestamps in arrival order (seconds) | 10,20,12,30 |
| Allowed lateness (seconds) | 5 |
A worked example
With the example inputs above, final watermark (seconds) is 25. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Final watermark (seconds) | 25 |
| Late event row numbers | 3 |
| Late event count | 1 |
How this is calculated
Final watermark (seconds)
Subtract allowed lateness from maximum event timestamp.
Late event row numbers
Compare each event with the watermark established by earlier arrivals.
Late event count
Count events strictly below their prior watermark.
Symbols and units
- a
- Event timestamps in arrival order (seconds)
- b
- Allowed lateness (seconds)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Conceptual continuous-time watermark before an event is maximum timestamp of previous arrivals minus allowed lateness; engine-specific millisecond offsets are not modeled. An event is late only if below that watermark; equality is accepted.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Final watermark (seconds); Late event row numbers; Late event count. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Conceptual continuous-time watermark before an event is maximum timestamp of previous arrivals minus allowed lateness; engine-specific millisecond offsets are not modeled. An event is late only if below that watermark; equality is accepted.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
Apache Flink Generating Watermarks ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →