Quick answer
Billing increment charts
6-minute increment
0.1 hour
10 blocks an hour; common for lawyers and consultants
15-minute increment
0.25 hour
4 blocks an hour; common for freelancers
104 minutes of tasks
1.9 h vs 2.25 h
Billed in 6-minute vs 15-minute blocks
Each task is rounded up to the next block. Find your minutes, read the billable hours, then multiply by your rate.
| Minutes worked | Bill |
|---|---|
| 1–6 | 0.1 hour |
| 7–12 | 0.2 hour |
| 13–18 | 0.3 hour |
| 19–24 | 0.4 hour |
| 25–30 | 0.5 hour |
| 31–36 | 0.6 hour |
| 37–42 | 0.7 hour |
| 43–48 | 0.8 hour |
| 49–54 | 0.9 hour |
| 55–60 | 1.0 hour |
| Minutes worked | Bill |
|---|---|
| 1–15 | 0.25 hour |
| 16–30 | 0.50 hour |
| 31–45 | 0.75 hour |
| 46–60 | 1.00 hour |
Your timer says 1 hour 44 minutes. What do you bill?
If you bill by the hour, your time log is a list of small pieces: a 6-minute call, an 11-minute email, 44 minutes on a draft. Clients don't get billed in odd minutes. You round each piece to a block, usually 6 or 15 minutes, add them up, and multiply by your rate. Do it by hand at the end of the month and it's easy to miss a task or round inconsistently.
This calculator does it for every task at once. You see the exact time, the billable time, how much the rounding added, and the invoice total. You can copy the lines straight into your invoice.
How to use the calculator
Step 1
Set your billing rules
Choose the increment in your contract, usually 6 or 15 minutes, and how to round. Most hourly billing rounds each task up. Add your hourly rate and currency if you want the amount.
Step 2
Enter each task
Type a short name and the hours and minutes from your timer or time log. Use Add task for more rows. Blank rows are skipped.
Step 3
Copy it to your invoice
Check the table for each task's billed time and amount, then press Copy invoice lines and paste them into your invoice or email.
Rounding each task vs. rounding the total
This is where the money is. When each task is rounded up, every task can add up to one block minus a minute. When you round the total once, you add at most one block for the whole invoice.
Say you have four 4-minute tasks for one client. In 15-minute increments, rounding each task up bills 4 × 15 = 60 minutes. Rounding the 16-minute total once bills 30 minutes. In 6-minute increments, it's 24 minutes vs. 18 minutes. The smaller the increment, the less rounding matters, which is why many professionals prefer 6-minute billing.
Round to nearest is the middle ground: an 8-minute task in 15-minute blocks rounds up to 15, and a 20-minute task rounds down to 15. The calculator still bills at least one block for any task you worked on, so a 3-minute call isn't billed as zero.
Example: five tasks at $300 an hour
Let's say your log for one client shows tasks of 6, 11, 17, 26 and 44 minutes. That's 104 minutes of real work, or $520 at $300 an hour.
6-minute blocks, each task up: 6 + 12 + 18 + 30 + 48 = 114 minutes = 1.9 hours
1.9 hours × $300 = $570
15-minute blocks, each task up: 15 + 15 + 30 + 30 + 45 = 135 minutes = 2.25 hours
2.25 hours × $300 = $675
Same work, a $155 difference. Neither is wrong if it's what your client agreed to. But if your contract doesn't say, 6-minute rounding is easier to defend, and your client will notice 15-minute charges for 5-minute emails.
Tips for fair and accurate billing
- Put the rule in writing. State your increment and rounding method in your proposal or contract.
- Log as you go. Time written down at the end of the week is usually less than time actually worked.
- Keep exact minutes in your log. Round only on the invoice, so you can always show the real time.
- Group tiny tasks. Ten 1-minute emails rounded up each to 15 minutes is 2.5 hours. Group them as one task first.
- Track non-billable time too. Admin and sales time doesn't go on the invoice, but it tells you if your rate covers your real hours.
For one long stretch of work from a start and end time, use the AM–PM Calculator. To convert minutes to decimal hours on their own, use the Minutes to Decimal Hours Calculator.
Questions about billable hours
How do I calculate billable hours?
Round each task’s time to your billing increment, add the rounded times, and convert to hours. Multiply by your hourly rate for the invoice amount. For 6-minute billing, a 17-minute task is 0.3 hours.
What is 0.1 billable hours?
6 minutes. In tenth-of-an-hour billing, any task from 1 to 6 minutes is billed as 0.1 hours, 7 to 12 minutes as 0.2 hours, and so on.
Should I bill in 6-minute or 15-minute increments?
Either is common. 6-minute billing is closer to your real time and easier to defend. 15-minute billing is simpler but adds more for short tasks. Use what your contract says, and say it in writing.
Do I round each task or the total?
Most hourly billing rounds each task up. Rounding the total once is fairer to the client when you have many tiny tasks. The calculator shows both, so you can see the difference.
How do I convert minutes to billable hours?
Divide by 60 for exact hours, then round to your increment. 44 minutes is 0.73 hours exactly, 0.8 hours in 6-minute billing, and 0.75 hours in 15-minute billing.
How much is 1 hour 30 minutes at $50 an hour?
1.5 hours × $50 = $75. No rounding is needed because 90 minutes is a whole number of 6-minute and 15-minute blocks.
Related calculators
- Time Card Rounding Calculator
Round clock-in and clock-out times for payroll.
- Time to Salary Calculator
Pay for one duration at an hourly rate.
- Minutes to Decimal Hours Calculator
Turn minutes into decimal hours.
- Timesheet Calculator
Add up a week of time in and time out.
Sources
- Common professional billing practice: tenth-of-an-hour (6-minute) and quarter-hour (15-minute) increments, rounded up per time entry, as described by legal billing software providers and bar ethics guidance on reasonable fees