What a Tenth of an Hour Is
An hour has 60 minutes, so a tenth of an hour (0.1) is 6 minutes. Billing in tenths means every task is recorded as a multiple of 6 minutes: 0.1, 0.2, 0.3 and so on.
Lawyers, accountants and many consultants bill this way, often because their engagement letters say so. It's precise enough for short tasks like a call or an email, and the numbers stay easy to add up.
Tenths to Minutes
| Tenths | Minutes | At $250 per hour |
|---|---|---|
| 0.1 | 6 | $25.00 |
| 0.2 | 12 | $50.00 |
| 0.3 | 18 | $75.00 |
| 0.4 | 24 | $100.00 |
| 0.5 | 30 | $125.00 |
| 0.6 | 36 | $150.00 |
| 0.7 | 42 | $175.00 |
| 0.8 | 48 | $200.00 |
| 0.9 | 54 | $225.00 |
| 1.0 | 60 | $250.00 |
Rounding Up or to the Nearest Tenth
Time rarely lands on a 6-minute mark, so you need a rule. There are two in common use:
- Round up: any part of a tenth counts as a full tenth, and the smallest entry is 0.1. A 14-minute call is 0.3. Common in legal billing.
- Round to the nearest tenth: 3 minutes or more into a tenth rounds up, less rounds down. The same 14-minute call is 0.2.
Whichever you use, use it every time and say so in your agreement. Rounding each task up adds up over a month, which is why some clients ask about it.
Converting Minutes to Tenths
Divide the minutes by 6 and round by your rule. 40 minutes ÷ 6 = 6.67 tenths: 0.7 hours either way. For hours and minutes, do the hours first: 2 hours 20 minutes is 2 + 20 ÷ 60 = 2.33, or 2.3 to the nearest tenth.
The Time Card Calculator turns start and end times into decimal hours for a whole week.
Setting It Up With Clients
Put the increment in your engagement letter or contract (“Time is billed in increments of one-tenth of an hour”), and show the hours on each invoice line as 0.3, 1.2 and so on. Clients who see the same increment on every line rarely question it.