How to round billable time: six-minute or fifteen-minute increments
· 7 min read
Pick one increment, decide whether you round up or to the nearest, write both into your agreement, and apply them to every entry without exception. Six-minute increments (tenths of an hour) follow the work closely. Fifteen-minute increments are simpler and round more. The choice matters less than being consistent and telling the client before the first invoice, and none of it works unless the minutes underneath are real.
What a billing increment is
An increment is the smallest unit of time you bill. Work is measured in minutes and invoiced in hours, and the increment is the step between the two.
Six minutes is one tenth of an hour, which is why it is popular: the invoice reads in clean decimals. Legal work is commonly billed this way.
Fifteen minutes is a quarter of an hour. Many freelancers and consultants use it because it is easy to explain and easy to add up.
Some people use half hours, or a one-hour minimum for anything that involves a call or a visit.
| Minutes | Tenths of an hour | Quarter hours |
|---|---|---|
| 6 | 0.1 | |
| 12 | 0.2 | |
| 15 | 0.25 | |
| 30 | 0.5 | 0.5 |
| 45 | 0.75 | |
| 60 | 1.0 | 1.0 |
Three ways to round, and what each does to a day
There are three rules in common use.
- Round up. Any started increment is billed in full. Seven minutes becomes twelve at six-minute increments, or fifteen at quarter hours.
- Round to the nearest. Seven minutes becomes six at six-minute increments, and zero at quarter hours. Ten minutes becomes twelve, or fifteen at quarter hours.
- A minimum, then nearest. Every entry bills at least one increment; beyond that it rounds to the nearest.
The differences look small on one entry. They are not small across a day. Take a day with five separate pieces of work for one client: 4, 9, 22, 31 and 48 minutes. That is 114 minutes of real work, or 1.9 hours.
| Rule | Each entry becomes | Billed |
|---|---|---|
| Six-minute, round up | 6, 12, 24, 36, 48 | 2.1 h |
| Fifteen-minute, round up | 15, 15, 30, 45, 60 | 2.75 h |
| Fifteen-minute, nearest | 0, 15, 15, 30, 45 | 1.75 h |
The same day is 1.75, 2.1 or 2.75 hours depending on the rule. None of those is a lie, as long as the client agreed to the rule. But the spread is the reason to choose on purpose. Rounding up at fifteen minutes adds the most when the day is made of many short tasks, and adds almost nothing when it is two long blocks.
Round each entry, or round the total?
This choice is less discussed and often matters more than the increment.
Rounding each entry treats every email and every quick fix as its own billable event. That is how the fifteen-minute, round-up row above reaches 2.75 hours from 1.9.
Rounding the day’s total adds the real minutes first and rounds once. The same 114 minutes stays at 1.9 hours with six-minute increments (114 is already a multiple of six) and becomes 120 minutes, or 2.0 hours, at fifteen.
Rounding the total is easier to defend and is close to what the client would guess if they watched you work. Rounding each entry is reasonable when each one really is a separate interruption that cost you more than its minutes (stopping other work, reloading the context). Either is fine. Say which.
Put the rule in writing
A rounding rule the client first learns about from an invoice is a dispute waiting to happen. One sentence in the agreement prevents it. It should state four things:
- The increment (six minutes, fifteen minutes).
- The direction (up, or to the nearest).
- What gets rounded (each entry, or each day’s total per client).
- Any minimum (for example, calls billed at no less than fifteen minutes).
Something like: “Time is recorded in minutes, totaled per day, and rounded up to the next six minutes.” Plain, and checkable.
One caution. Some professions and some places have their own rules about how time may be billed, and attorneys in particular are bound by professional conduct rules. This is a description of common practice, not legal advice; check what applies to you.
Get the raw minutes right first
Rounding is the second step. The first is knowing that the task took 22 minutes and not “about half an hour.” If the minutes are reconstructed from memory on Friday, you have already rounded once in your head, usually to the nearest quarter or half hour, and the written rule is being applied to a guess.
A timer gives real minutes when it runs. The short entries are the ones that never get a timer: nobody starts a clock for a four-minute reply.
An automatic record catches those. Punchcard sits in the menu bar and notices which app is in front through the day. At your closing time it prints a paper receipt with a time on each line and a day total, and its CSV export has one row per session: start, end, app and seconds. Those are raw, unrounded figures.
Be clear about where it stops. Punchcard has no clients, projects, billable rates or invoicing, and it does not round anything. It records app names (and site names if you turn on itemized browsing), never document names or window titles, so it cannot know which client a session belonged to. You assign the time and apply the rule. If “where did my day go” is the question, it answers that well; if you need per-client timers and invoices, it is the wrong tool. The CSV export works without a license; printing receipts after the first two is $9 once.
In a spreadsheet, with minutes in cell A2, the rounding itself is one formula:
=CEILING(A2, 6) / 60
rounds up to the next six minutes and gives hours.
=MROUND(A2, 15) / 60
rounds to the nearest fifteen. Both work in Numbers.
For the tracking side, How to track billable hours without forgetting to start the clock goes into more detail, and Turning receipts into a simple invoice line covers the step after rounding.
Questions
Is rounding up dishonest?
Not when it is disclosed and applied the same way every time. What clients object to is stacking: many tiny entries each rounded up, so that an hour of real work becomes two. Rounding the day’s total avoids that.
Which increment should I choose?
If your work comes in short, frequent pieces (support, quick edits, calls), six minutes keeps the bill close to the work. If it comes in long blocks, fifteen minutes is simpler and the difference is negligible.
Should I bill for a two-minute email?
That is what the written rule decides. A common fair approach is to collect the day’s short tasks for a client into one entry and round that once.
What if a client disputes the hours anyway?
Then the raw record matters more than the rule. Proving your hours when a client disputes an invoice covers what to show and how.