Billing in 6-minute increments means recording time in tenths of an hour: 6 minutes is 0.1, 30 minutes is 0.5. It's the common standard in law firms and is widely used by accountants, consultants and agencies, because tenths make the maths easy.
Minutes to tenths
| Minutes worked | Billed (0.1 hr) | Billed (0.25 hr) |
|---|---|---|
| 1–6 | 0.1 | 0.25 |
| 7–12 | 0.2 | 0.25 |
| 13–18 | 0.3 | 0.5 |
| 19–24 | 0.4 | 0.5 |
| 25–30 | 0.5 | 0.5 |
| 31–36 | 0.6 | 0.75 |
| 37–42 | 0.7 | 0.75 |
| 43–48 | 0.8 | 1.0 |
| 49–54 | 0.9 | 1.0 |
| 55–60 | 1.0 | 1.0 |
This table rounds up, which is the most common approach. Some businesses round to the nearest increment instead. Whichever you use, say so in your terms.
6 minutes or 15?
- 6 minutes (0.1 hr) is more precise. A quick email or call costs the client 6 minutes, not 15, which is easier to defend on an itemised invoice.
- 15 minutes (0.25 hr) is simpler to track by hand and suits work that comes in bigger blocks. It overstates short tasks more.
- Some firms set the increment per client, often because a client's billing guidelines ask for one.
Round the invoice, not the record
The safest way to round is to keep your real minutes and only round what you bill. That way you can always show what was worked, change the increment for a client later, and see how much rounding adds up to.
That's how Punchcard does it. When you review entries before pushing to Xero Projects, you can round to 6, 15 or 30 minutes. Only the pushed entry is rounded; your raw time stays on your Mac.