# HowManyHours.com

Free browser-based calculators for work hours, time intervals, time off and travel time. All calculations run client-side; entered values are never sent to a server and are held only in the URL fragment.

## Tools

- [Time card calculator](https://howmanyhours.com/timecard-calculator/): Totals a week of start and end times, deducts unpaid breaks, and splits the result into regular, overtime and double-time hours with optional gross pay. Wall-clock hours.
  Methodology: https://howmanyhours.com/timecard-calculator/#methodology
- [Overtime calculator](https://howmanyhours.com/overtime-calculator/): Same weekly engine with daily overtime enabled by default; applies daily thresholds before the weekly one so hours are never counted twice.
  Methodology: https://howmanyhours.com/overtime-calculator/#methodology
- [Hours between two times](https://howmanyhours.com/hours-between/): Real elapsed time between two datetimes in an explicit IANA time zone, correct across daylight saving transitions. The zone is part of the shareable URL.
  Methodology: https://howmanyhours.com/hours-between/#methodology
- [PTO accrual calculator](https://howmanyhours.com/pto-calculator/): Paid time off accrued per pay period, per hour worked, or as a lump sum, with starting balance, hours used and a policy balance cap.
  Methodology: https://howmanyhours.com/pto-calculator/#methodology
- [Decimal hours converter](https://howmanyhours.com/decimal-hours-converter/): Converts decimal hours to hours and minutes and back, in both directions.
  Methodology: https://howmanyhours.com/decimal-hours-converter/#methodology
- [Minutes to hours](https://howmanyhours.com/minutes-to-hours/): Converts a number of minutes to hours and minutes and to decimal hours.
  Methodology: https://howmanyhours.com/minutes-to-hours/#methodology
- [Military time converter](https://howmanyhours.com/military-time-converter/): Converts 24-hour time to 12-hour time and back, with a full 24-hour reference chart rendered in the page.
  Methodology: https://howmanyhours.com/military-time-converter/#methodology
- [Fly or drive](https://howmanyhours.com/fly-or-drive/): Great-circle distance between two cities by the haversine formula, door-to-door flight time including airport overhead, driving time from a configurable road detour factor, and fuel cost.
  Methodology: https://howmanyhours.com/fly-or-drive/#methodology

## Notes

- Every tool page states its formula and its assumptions in a "How this is calculated" section, anchored at #methodology.
- The time card uses wall-clock hours; "hours between two times" uses real elapsed time. They differ by an hour across daylight saving transitions, and each page says which model it uses and why.
- Fly-or-drive distances are great-circle. Road distance is approximated with a detour factor and is not a routed distance; no check is made for whether a road route exists.
- City coordinates are from GeoNames (CC BY 4.0).