Billable Hours Chart: Minutes to Tenths, Quarters and Decimal Hours
Billable hours chart in tenths (six-minute increments)
One tenth of an hour is six minutes. Time is rounded up to the next block, which is the common convention in US law firms and in most consultancies that bill in tenths.
| Minutes worked | Tenths of an hour |
|---|---|
| 1 to 6 | 0.1 |
| 7 to 12 | 0.2 |
| 13 to 18 | 0.3 |
| 19 to 24 | 0.4 |
| 25 to 30 | 0.5 |
| 31 to 36 | 0.6 |
| 37 to 42 | 0.7 |
| 43 to 48 | 0.8 |
| 49 to 54 | 0.9 |
| 55 to 60 | 1.0 |
A 4-minute email is 0.1, a 25-minute call is 0.5, a 50-minute meeting is 0.9. At $250 an hour those are $25, $125 and $225.
Billable hours chart in quarters (fifteen-minute increments)
Quarters are the increment most agencies, designers and developers use. The blocks are bigger, so the rounding matters more: a 16-minute task bills as half an hour.
| Minutes worked | Quarters of an hour |
|---|---|
| 1 to 15 | 0.25 |
| 16 to 30 | 0.50 |
| 31 to 45 | 0.75 |
| 46 to 60 | 1.00 |
The same 25-minute call is 0.5 in quarters, the same as in tenths, but a 20-minute call is 0.5 in quarters and 0.4 in tenths. At $200 an hour that is $100 against $80, which is why the increment belongs in the contract.
Decimal hours chart: every minute from 1 to 60
For payroll, timesheets and spreadsheets you need the exact decimal, not an increment. Divide the minutes by 60. The table gives every value rounded to two decimals.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 1 min | 0.02 | 31 min | 0.52 |
| 2 min | 0.03 | 32 min | 0.53 |
| 3 min | 0.05 | 33 min | 0.55 |
| 4 min | 0.07 | 34 min | 0.57 |
| 5 min | 0.08 | 35 min | 0.58 |
| 6 min | 0.10 | 36 min | 0.60 |
| 7 min | 0.12 | 37 min | 0.62 |
| 8 min | 0.13 | 38 min | 0.63 |
| 9 min | 0.15 | 39 min | 0.65 |
| 10 min | 0.17 | 40 min | 0.67 |
| 11 min | 0.18 | 41 min | 0.68 |
| 12 min | 0.20 | 42 min | 0.70 |
| 13 min | 0.22 | 43 min | 0.72 |
| 14 min | 0.23 | 44 min | 0.73 |
| 15 min | 0.25 | 45 min | 0.75 |
| 16 min | 0.27 | 46 min | 0.77 |
| 17 min | 0.28 | 47 min | 0.78 |
| 18 min | 0.30 | 48 min | 0.80 |
| 19 min | 0.32 | 49 min | 0.82 |
| 20 min | 0.33 | 50 min | 0.83 |
| 21 min | 0.35 | 51 min | 0.85 |
| 22 min | 0.37 | 52 min | 0.87 |
| 23 min | 0.38 | 53 min | 0.88 |
| 24 min | 0.40 | 54 min | 0.90 |
| 25 min | 0.42 | 55 min | 0.92 |
| 26 min | 0.43 | 56 min | 0.93 |
| 27 min | 0.45 | 57 min | 0.95 |
| 28 min | 0.47 | 58 min | 0.97 |
| 29 min | 0.48 | 59 min | 0.98 |
| 30 min | 0.50 | 60 min | 1.00 |
Use this table when hours are added up before they are billed: a week of 37 hours and 20 minutes is 37.33 hours, and 37.33 × $95 is $3,546.35. Apply the billing increment afterwards, per task, not on the weekly total.
Rounding rules: up, nearest, or none
The chart is only half the agreement. The other half is the rounding rule.
- Round up to the next increment. The default in legal billing: 7 minutes is 0.2. Simple, and it always favours the firm, which is why some clients push back.
- Round to the nearest increment. 7 minutes is 0.1, 10 minutes is 0.2. Fairer over a month, slightly more work to explain.
- No rounding, bill the decimal. 7 minutes is 0.12 hours. Common in software and consulting work that is tracked with a timer and invoiced from the timesheet.
Whichever you choose, three things keep it clean: write the rule into the engagement letter, apply it per task and not per day, and make sure the time tracker rounds the same way the invoice does. Where those two disagree, the difference shows up as write-offs.
From the chart to the invoice
A chart works for one person and a handful of clients. With a team, the conversion has to happen automatically, at the moment the hours are approved. In FlowQi, time is logged against the client and the project, and approved hours become invoice lines, so the increment you agreed is applied once and the same way for every client. See time tracking for how that fits with projects and invoicing, and the billable hours page for what a healthy billable share looks like.