When to use this calculator
Find the weekday name for a Gregorian calendar date. Uses the proleptic Gregorian calendar for years 1600–9999.
Explore the calendar dates & age calculators for other questions in this topic. For a related calculation, use the Day of Year Calculator: Find the ordinal position of a date within its Gregorian year.
PUTTING IT INTO PRACTICE
Day of the Week: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Calendar date | 2026-10-17 |
| Result | Saturday |
- Check the input labels and enter the example values above.
- Apply the relationship: Determine the weekday from the Gregorian calendar date..
- The result is Saturday , rounded for display.
How to interpret your result
Uses the proleptic Gregorian calendar for years 1600–9999.
Choose whether an interval includes the start or end boundary. Month and year additions use explicitly stated clamping rules when a destination day does not exist. Date-only arithmetic is kept independent of local daylight-saving hour shifts.
Frequently asked questions
Does adding one month always add the same number of days?
No. Calendar months vary in length. A day-count addition and a calendar-month addition solve different questions.
When is the day of the week calculator useful?
Find the weekday name for a Gregorian calendar date. Uses the proleptic Gregorian calendar for years 1600–9999.
How do I use the day of the week calculator?
Enter calendar date. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Determine the weekday from the Gregorian calendar date..
What should I check before using the result?
Uses the proleptic Gregorian calendar for years 1600–9999.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see MDN: date values and calendar handling ↗. This is a topic reference, not an external review or endorsement of this tool.
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