Weekday Calculator
Calculate an ISO weekday and weekday name for a Gregorian calendar date.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Input
Result
Calculated locally and deterministically with standard formulas.
Enter a value to see the result
Primary: 0 · Secondary: 0
What this tool does
- Calculate quickly with standard formulas.
- Validate date, dimension, or unit data.
Example
Input
2024-02-29
Output
2024-02-29 is Thursday (ISO weekday 4)
All inputs are strictly validated; calculation is offline and deterministic.
Frequently asked questions
Does it read the system clock?
No. Results depend only on explicit input.
Does it use the network?
No. All calculations run locally in the browser.
What happens to invalid values?
Malformed, impossible, or out-of-range values are rejected.
Keywords：weekday星期几计算器Weekday Calculator本地计算