How to Calculate Work Hours (Timesheets & Overnight Shifts)

Guides · Calculator · Updated 2026

Whether you’re a freelancer billing by the hour or an HR manager verifying timesheets, manual hour‑math is a pain. A shift that starts at 9:15 AM and ends at 6:45 PM with a 45‑minute break isn’t hard to calculate — until the shift crosses midnight. Then it becomes 21:00 to 06:00, and simple subtraction fails. In this guide we explain the standard time‑card formula, how to handle overnight shifts, and why decimal hours (7.5) matter more than hh:mm (7:30) when it’s time to bill.

The timesheet formula

Work hours = (End time − Start time) in minutes − break minutes. If the end time is earlier than the start time (overnight), add 24 hours to the end time before subtracting. Convert the final minutes back to hours and minutes, or to decimal hours by dividing minutes by 60.

Decimal hours = total minutes ÷ 60
Example: 7 hours 30 minutes = 7 + 30/60 = 7.5 hours. This is the number you multiply by your hourly rate.

Step‑by‑step: use the work hours calculator

  1. Open the Work Hours Calculator tool. Five default weekday rows are ready.
  2. For each day, enter start time, end time, and break duration in minutes. Leave blank for non‑working days.
  3. If a shift crosses midnight, simply enter the real start and end times (e.g., 22:00 to 06:00). The tool adds 24 hours automatically.
  4. Add an optional hourly rate to see total pay. Add or remove rows as needed.
  5. The result panel shows total hours:minutes, decimal hours, and total pay. Use the decimal hours figure to fill invoices or track billable time.
💡 Tip: Always record your time in your own records, not just on a client’s platform. A personal time‑card tool gives you an independent verification of what you’re owed. And when you send an invoice, list decimal hours (e.g., 37.75) — it’s the standard in most accounting software.

Overnight shift example

Start: 10:00 PM (22:00), End: 6:00 AM (06:00), Break: 30 min. Since 06:00 is less than 22:00, add 24h to end → 30:00. Difference = 30:00 − 22:00 = 8:00. Subtract break → 7:30. That’s 7 hours 30 minutes, or 7.5 decimal hours. At ₹500/hour, that’s ₹3,750 for the shift. The calculator handles this logic automatically — no manual adjustments needed.

Frequently Asked Questions

How do I track a lunch break that varies each day?

Enter the actual break minutes for each day in the break column. You can adjust per day; the tool isn’t restricted to a fixed break length.

What if I work less than an hour?

Enter times accordingly. The calculator handles any duration, even a few minutes, and will show decimal hours like 0.75 for 45 minutes.

Can I use this for weekly or monthly totals?

Yes, add as many rows as you need (click “Add Day”) and the tool sums everything. For a monthly view, simply keep adding rows.

Why do I need decimal hours instead of hh:mm?

Payroll and billing systems use decimal hours because they’re easier to multiply by an hourly rate. For example, 7:30 in decimal is 7.5, which directly gives pay when multiplied.

Is it free and private?

Yes — the tool runs entirely in your browser, free, with no sign‑up and nothing uploaded to a server.

Try the Work Hours Calculator
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