Time & Planning Toolkit
Ten planning utilities in one place: count business days (skipping weekends), measure the difference between two dates, plan a meeting time across timezones, convert Unix timestamps, work out an age, run a countdown, find an ISO week number, check a leap year, tally working hours, and convert currency. Pick a utility and fill in the fields it needs. Everything is computed locally in your browser, including currency conversion, which uses a built-in reference rate table so the tool works entirely offline.
How to use this tool
- Choose a utility from the menu.
- Fill in only the fields that utility uses — dates, times, a timezone pair, a timestamp, a year, or a currency pair.
- Read the result; date maths uses UTC to stay stable across timezones.
- For currency, the tool shows whether the rate is live or a reference fallback.
- Timezone results use standard offsets and do not model daylight saving.
The formula
Date and time calculations rest on the calendar’s structure: fixed day lengths, weekly cycles, leap-year rules and timezone offsets. Business days skip weekends and holidays; ISO weeks start on Monday; Unix time counts seconds from 1 January 1970 UTC.
total_days = (end − start) ÷ 86,400 seconds
leap_year = divisible by 4, except centuries not divisible by 400
unix_seconds = milliseconds_since_1970 ÷ 1000- business day
- Weekday that is not a holiday
- ISO week
- Monday-start; week 1 holds the first Thursday
- Unix time
- Seconds since 1970-01-01T00:00:00Z
Timezone results here use standard offsets and do not model daylight saving, which shifts many zones by an hour for part of the year.
Worked examples
Business days
- Given
- 1 Jan 2026 → 31 Dec 2026
- Result
- ≈ 261 working days
Counts weekdays between the dates, skipping Saturdays and Sundays.
Timezone
- Given
- 09:00 New York → London
- Result
- 14:00
London is 5 hours ahead of New York in standard time.
Unix
- Given
- 1700000000
- Result
- 14 Nov 2023, 22:13:20 UTC
Interprets the value as seconds since 1 Jan 1970 UTC.
Frequently asked questions
The core calculation skips weekends (Saturday and Sunday) between the two dates. Public holidays vary by country and region, so they are not assumed automatically — treat the result as working days before local holidays, and subtract any that apply to you. The underlying engine can exclude specific holiday dates when they are supplied.
No. It uses each zone’s standard UTC offset to keep results predictable and it clearly says so. During daylight-saving periods, many zones shift by an hour, so around those dates verify against a live clock. The planner is best for a quick "what time will it be there" check.
It is the number of seconds since 1 January 1970 at 00:00 UTC, a common way computers store time. This tool converts a timestamp to a readable UTC date and back. It accepts seconds by default; multiply by 1000 for milliseconds, which some systems use.
Using the ISO 8601 standard: weeks start on Monday, and week 1 is the week containing the year’s first Thursday. This is why early-January dates can fall in the last week of the previous year — for example, 1 January 2021 is in ISO week 53 of 2020.
They are indicative. The tool uses a built-in reference rate table that runs entirely on your device, so no data leaves your browser. Because these rates are fixed rather than live, they can lag the market and should be treated as an approximation — always confirm the current rate with your bank or provider before any real transaction.
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