The Time Duration Calculator and the Time Card Calculator both work with clock times, but at very different scales. The time duration calculator measures one interval — the elapsed time between a start and end time, or a base time plus or minus an interval — and reports it in hours, minutes, and seconds with supporting decimal totals. The time card calculator totals a repeated weekly schedule: the days worked, a daily start and end time, an optional lunch deduction, and a weekly overtime threshold, producing total, regular, and overtime hours for the week. If you need to know how long one thing lasted, use the duration tool; if you need to check a week of scheduled work hours against an overtime policy, use the time card tool.
Both calculators handle shifts that cross midnight by adding one 24-hour day when the end is earlier than the start, and neither one is a time-zone or payroll-authority tool: daylight-saving transitions are not modeled, and neither result is a legal timekeeping record.
What each calculator does
The Time Duration Calculator converts clock times to seconds after midnight and offers three modes. Time difference takes a start and end clock time and returns the elapsed duration, adding one day when the end is earlier than the start. Add time and subtract time take a base clock time and an interval and return the resulting time of day, wrapping within the 24-hour clock. Supporting outputs express the same duration as total hours (decimal hours for billing), total minutes, and total seconds. Its article is explicit about the boundary: the tool is clock-only, does not track calendar dates beyond a single next-day adjustment, and is intended for intervals shorter than 24 hours.
The Time Card Calculator turns a repeated weekly pattern into paid hours: you select the days worked, enter one daily start and end time in 24-hour format, choose whether to subtract a lunch duration, and set the weekly overtime threshold (40 hours by default, matching the common federal FLSA weekly threshold for many nonexempt U.S. employees). It processes days Monday through Sunday, filling regular hours up to the threshold and counting the rest as overtime, and reports total, regular, and overtime hours plus a per-day breakdown. Its article notes the same daily schedule applies to every selected day, so irregular schedules are handled by combining separate spans manually.
Side-by-side comparison
| Feature | Time Duration calculator | Time Card calculator |
|---|---|---|
| Scope | One clock interval | A repeated weekly schedule |
| What you enter | Start/end times, or a base time plus an interval | Worked days, daily start/end, lunch, overtime threshold |
| Primary result | Duration in hours, minutes, and seconds | Weekly total, regular, and overtime hours |
| Breaks | Not handled — clock interval only | Optional lunch deduction per day |
| Overtime | None | Sequential split against a weekly threshold (default 40h) |
| Midnight crossing | Adds one day when end is earlier than start | Adds 24 hours when end is earlier than or equal to start |
| Best for | Workouts, edits, run sheets, study blocks, support windows | Checking timesheets and planning weekly coverage |
When to use which
Use the Time Duration Calculator when the question is about a single interval: how long a meeting, workout, edit, or study block ran, what time it will be after an interval, or what time to start to finish by a deadline. Its article points there for work logs, event run sheets, kitchen timing, and technical logs, and its total-hours output is handy when a spreadsheet wants decimal hours.
Use the Time Card Calculator when you are totaling scheduled work: checking a weekly timesheet, planning coverage, or verifying that lunch deductions and overnight shifts were handled consistently. Its article also warns where the boundary lies — it is arithmetic and planning, not a legal payroll record, and official payroll may require exact punch times, rounding rules, paid breaks, daily overtime, state law, or collective bargaining terms.
Both pages point to the same neighbors: the Shift Calculator handles a single shift with breaks, and the Time Zone Calculator converts times across zones before you measure a cross-zone interval, because daylight-saving changes can make wall-clock subtraction wrong on transition days.
Where to start
- Time Duration Calculator — a single clock interval with add and subtract modes.
- Time Card Calculator — weekly total, regular, and overtime hours with lunch deduction.