Billable Hours Calculator
Turn the time you worked and your hourly rate into an invoice amount — rounded to your billing increment.
Enter how long you worked and what you charge, and this calculator returns the amount to invoice — along with the billable hours in decimal form. Most freelancers and agencies bill in fixed increments (6, 15, or 30 minutes), so you can round the tracked time up to the next block and see exactly how much rounding adds. Set the increment to “Exact” to bill the precise time instead.
How this calculation works
- 01Convert the hours and minutes you worked into total minutes.
- 02If a billing increment is set, round those minutes up to the next whole increment.
- 03Divide the billable minutes by 60 to get billable hours in decimal (the format invoices use).
- 04Multiply the billable hours by your hourly rate to get the amount to invoice.
- —Time is always rounded up to the next increment, which is how time-based billing conventionally works — 1h 05m at a 15-minute increment bills as 1h 15m.
- —A 6-minute increment equals 0.1 decimal hours; 15 minutes equals 0.25; 30 minutes equals 0.5.
- —The amount is your rate × billable decimal hours — it does not add tax, discounts, or fees.
- —Use the “Exact” option to bill the precise tracked time with no rounding.
Worked examples
6h 20m at $75/hour, rounded up to 15-minute increments
6.50 billable hours → $487.50 (rounded up 10 min)
2h 05m at $120/hour, rounded up to 6-minute increments
2.10 billable hours → $252.00 (rounded up 1 min)
3h 40m at $90/hour, billed exactly
3.67 billable hours → $330.00
Frequently asked questions
- How do you calculate billable hours?
- Take the time you worked, convert it to decimal hours (for example 6 hours 20 minutes is about 6.33), and multiply by your hourly rate. If you bill in increments, round the time up to the next block first — this calculator does both and shows the amount to invoice.
- What are billing increments and which should I use?
- A billing increment is the smallest block of time you charge for — commonly 6 minutes (0.1 hour), 15 minutes (0.25 hour), or 30 minutes. Time is rounded up to the next block, so a 6-minute increment is the most client-friendly and 30 minutes the most generous to you. Pick the one your contract specifies.
- How do I turn worked time into an invoice amount?
- Multiply your billable decimal hours by your hourly rate. For 6.5 hours at $75, that is $487.50. The trick is getting accurate billable hours in the first place — which is far easier when the time was tracked as you worked rather than reconstructed later.
- Can InstaClock track billable hours for me?
- Yes — that is exactly what it is built for. Tag work as billable as you go, keep client work separate from admin, and InstaClock keeps the running billable totals and effective rate, so the number you put on an invoice matches the time you actually spent.
Stop calculating. Start tracking.
InstaClock keeps your hours, weekly totals, and visual reports running automatically — no start-and-end-time arithmetic required.
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