Days between dates calculator
Measure elapsed days between two dates.
Your inputs
Your results
Ready when you areYour results will appear here.
How it works
Validate two real ISO calendar dates and subtract their UTC day indices. Optionally count both endpoints rather than elapsed-day boundaries.
Read the source reference ↗A few things to know
Calendar days only, not business days, hours or local-time DST intervals. End must not precede start. Dates use four-digit years and real calendar-date validation.
When to use this tool
Choose between elapsed day boundaries and inclusive calendar-day counting. The same start and end date means zero elapsed days but one included date.
- Count an interval.
- Review inclusive deadlines.
- Compare date ranges.
How to use days between dates calculator
Prepare the inputs
Enter the quantities and units used by your source.
Choose the settings
Choose the assumptions and compare them with your actual situation.
Review and export
Review the result, then download the calculation report.
Try the supplied example
Inputs
start: 2026-01-01; end: 2026-01-31; count: Elapsed days
Result
January 1 to January 31 has 30 elapsed days or 31 inclusive days.
What it means
Match the convention used by your agreement or report.
Common mistakes to avoid
Use the convention required by your task
Use the convention required by your task.
Calendar days are not business days
Calendar days are not business days.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
Are weekends included?
Yes. Every calendar day counts.
Does this calculate business days?
No. Holidays and working-day calendars are not modeled.
What does inclusive mean?
Both start and end dates are counted.
What if both dates match?
Elapsed count is zero; inclusive count is one.
Does daylight saving affect it?
No. UTC day indices avoid local-time DST hour differences.
Are leap years handled?
Yes. Date validation and UTC arithmetic use the real calendar.
Are my inputs uploaded or stored?
Processing happens locally in your browser. This tool does not upload inputs. Downloads stay on your device; sharing or opening them in another service is your choice.
What should I check before using the output?
Calendar days only, not business days, hours or local-time DST intervals. End must not precede start. Dates use four-digit years and real calendar-date validation.
Explore the topic in the blog
Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.