7 Free Date & Time Tools That Will Save You Hours Every Week

Time zone math ruins more meetings than bad Wi-Fi. Between calculating business days, checking if a holiday falls on a Friday, or figuring out what “2026-03-26T09:00:00-04:00 to 2026-03-27T10:30:00+08:00” even means in plain English — it’s a time sink.

These 7 free tools handle it all. No sign-up. No ads. Just working calculators.

1. Timezone Duration Calculator

The most common timezone question: “What time is it for them?” The second most common: “How long is the gap between these two timestamps, really?”

This tool answers both. Enter any two ISO 8601 timestamps with their respective timezones, and it returns the exact duration, the offset difference in hours/minutes, and a plain-English summary — including current local time for both zones.

What makes it stand out is the DST awareness. It accounts for daylight saving time shifts automatically, so a “13 hour gap” doesn’t turn into 14 when the clocks change in between.

Use it when: You’re scheduling a handoff with a team in Beijing, London, and New York and need to know the exact overlap window.

Try it: Timezone Duration Calculator →

2. ICS Calendar Recurrence Rule Expander

Calendar apps like Google Calendar and Apple Calendar use iCalendar (ICS) format to handle recurring events. The recurrence logic lives in an RRULE — something like FREQ=WEEKLY;BYDAY=MO,WE;COUNT=10. But most tools can’t show you which actual dates that generates.

This tool takes any VEVENT block (or a full .ics file), parses the RRULE, and expands it into concrete occurrences. You can exclude holidays, cap the max occurrences, and export the result as JSON, a flattened ICS file, or both.

Use it when: You need to export a recurring team meeting to a project management tool that doesn’t understand RRULE natively.

Try it: ICS Calendar Recurrence Rule Expander →

3. Time Zone Workflow Scheduler

The hardest scheduling problem: find a 60-minute meeting slot that works for someone in New York (9am–5pm), someone in London (2pm–10pm their time), and someone in Shanghai (9:30am–6:30pm their time) — while respecting weekends.

This tool does exactly that. Input each participant’s timezone and working window, set your meeting duration, and it searches a date range for every overlapping slot. You get a visual breakdown per day and an ICS file you can import directly into your calendar.

Use it when: You manage cross-timezone teams and are tired of the “does 3pm your time work?” back-and-forth.

Try it: Time Zone Workflow Scheduler →

4. Business Day Calculator

Sometimes you need to add 5 business days to a deadline. Sometimes you need to count how many business days fall between two project milestones. This tool does both — and it tells you exactly how many weekend days it skipped in the process.

It returns the resulting date, the total calendar days elapsed, and a breakdown of business vs. weekend days counted.

Use it when: A vendor promises “5 business days” delivery and you need to know if that hits before or after the weekend.

Try it: Business Day Calculator →

5. Holiday Calculator

Business days aren’t just Monday–Friday. They also aren’t every day someone decides to take off. This tool calculates public holidays for a specific year and country — covering US, UK, Canada, Australia, Germany, France, China, Japan, and Brazil.

You can list all holidays for a year, or check a specific date to see if it’s a holiday. Fixed holidays (like July 4th) and variable holidays (like US Thanksgiving, which falls on the 4th Thursday of November) are both handled correctly.

Use it when: You need to confirm a delivery date won’t land on a public holiday before telling the client.

Try it: Holiday Calculator →

6. Date Overlap Checker

Project A runs January 1 – March 31. Project B runs February 15 – May 30. Do they overlap, and by how many days?

Paste in any number of date ranges (format: Name, Start, End per line) and the tool checks every pair for overlaps. When overlaps exist, it shows the exact overlap period and duration in both days and hours.

Use it when: You’re a project manager confirming that two concurrent initiatives won’t compete for the same team members’ time.

Try it: Date Overlap Checker →

7. Time Duration Formatter

You’ve got a duration in milliseconds (say, 131625000). What does that actually mean in human terms? This tool converts any duration to HH:MM:SS, human-readable text (“1 day, 12 hours, 33 minutes, 45 seconds”), ISO 8601 duration format (P1DT12H33M45S), and Unix timestamps.

It accepts milliseconds, seconds, minutes, hours, days, or weeks as input — and lets you pick which output formats you want.

Use it when: A log file gives you a duration in milliseconds and you need to explain it to a non-technical stakeholder.

Try it: Time Duration Formatter →

The Unresolved Problem

These tools handle the mechanics of date and time well. But there’s still no great solution for conflict resolution across calendar systems — when Google Calendar, Apple Calendar, and Outlook each interpret a recurring event’s RRULE slightly differently, and you need to figure out which one is right.

If you’ve found a way around that, I’d love to hear it.

All 7 tools are free, run in the browser, and require no sign-up at elysiatools.com.