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Billable Hours Chart: 6-Minute Increments Explained

By Frame Sixty Labs · Last updated: September 30, 2026

What is the billable hours chart for 6-minute increments?

An hour has 60 minutes, so a tenth of an hour is 60 ÷ 10 = 6 minutes. The chart below shows both rounding rules you are likely to meet. Round up means any part of a 6-minute block bills as the whole block. Nearest tenth rounds to whichever tenth is closer, with the halfway point (3 minutes into a block) going up.

Under the nearest-tenth rule, 1 or 2 minutes rounds to 0.0, which is why most billing policies that use it also set a minimum entry of 0.1. For entries longer than an hour, keep the whole hours and look up the leftover minutes: 1:22 is 1 hour plus 22 minutes, so 1.4 under either rule.

How do you convert minutes to tenths without the chart?

Divide the minutes by 6. The whole-number part is the tenths you have completed; what you do with the remainder is the rounding rule.

• 38 minutes: 38 ÷ 6 = 6.33. Round up gives 7 tenths (0.7); nearest gives 6 tenths (0.6).
• 51 minutes: 51 ÷ 6 = 8.5. Round up gives 0.9; nearest also gives 0.9, because the halfway point goes up.
• 2 hours 14 minutes: 134 ÷ 6 = 22.33. Round up gives 2.3; nearest gives 2.2.

Going the other way, multiply the tenths by 6: 0.7 hours is 7 × 6 = 42 minutes. This is the step people get wrong when reading an invoice. 1.3 hours is 1:18, not 1 hour 30 minutes, and 1:30 is 1.5, not 1.3. Minutes are sixtieths of an hour, not hundredths — how to convert minutes to decimal hours has the full minute-by-minute table.

How do you calculate billable hours step by step?

1. Record the actual time for each task in hours and minutes, as you go. Reconstructing a day from memory is where most billing errors start.
2. Convert each entry to tenths using the chart and the rounding rule in your agreement.
3. Add the tenths. They are ordinary decimals, so they add like any other numbers.
4. Multiply by the hourly rate.
5. Check against the actual total by adding the real durations in H:MM, so you know how far rounding moved the bill.

Worked example: one day, seven entries, $150 an hour

A consultant bills $150 an hour and logs seven tasks for one client in a day. Here is each entry under four different rules:

The actual time in H:MM: 0:07 + 0:04 = 0:11, + 1:22 = 1:33, + 0:38 = 2:11, + 0:51 = 3:02, + 2:14 = 5:16, + 0:13 = 5:29. That is 329 minutes, or 329 ÷ 60 = 5.4833 hours.

What the table shows:

• Nearest tenth stays close to the truth. Some entries round up and some round down, so 5.5 hours is only 1 minute more than the 5:29 actually worked, and $2.50 more than the exact figure.
• Rounding every entry up adds 25 minutes. 5.9 hours is 5:54, and the bill is $62.50 higher than exact time. Every entry can only move one way, so the difference grows with the number of entries, not the length of the day.
• Quarter-hour blocks add 46 minutes. 6.25 hours is 6:15, $115.00 over exact. The two shortest tasks, 11 minutes between them, bill as half an hour.

Should you round each entry or the total?

It changes the answer, so it should be settled before the first invoice. Using the same day:

• Round each entry up, then add: 5.9 hours, $885.00.
• Add the actual time, then round the total up once: 329 ÷ 6 = 54.83, so 55 tenths — 5.5 hours, $825.00.

That is a $60.00 gap on one day from the order of two steps. Per-entry rounding is the traditional convention where each task appears as its own line on the bill; rounding the total is common for freelancers who invoice a single figure per day or per project. Neither is wrong on its own, but the client should know which one they agreed to.

The same logic applies to how tasks are split. Ten separate 2-minute calls logged as ten round-up entries bill as 10 × 0.1 = 1.0 hour. The same 20 minutes logged as one entry bills as 0.4. At $150 an hour that is $150 against $60 for identical work, which is why many agreements say something about minimum entries and how short tasks are grouped.

How does 6-minute billing compare with other increments?

Smaller increments track real time more closely and make short tasks worth recording. Larger ones are simpler to read but move further from the clock. For the payroll side of quarter-hour rounding, see timesheet rounding and the 15-minute rule.

How many billable hours do you need per day?

Annual targets are easier to manage as a daily number. A target of 1,800 billable hours over 50 working weeks is 1,800 ÷ 50 = 36 hours a week, and 36 ÷ 5 = 7.2 hours a day. In clock time, 7.2 hours is 7:12 — 0.2 × 60 = 12 minutes — not 7:20.

The same arithmetic for other targets, over 50 weeks of 5 days:

These are billable hours, not hours at work. Admin, training and unbilled calls sit on top, so the working day is longer than the billable figure.

Frequently asked questions

How many minutes is 0.1 of an hour?

Six minutes. From there, 0.2 is 12 minutes, 0.3 is 18, 0.5 is 30 and 0.7 is 42.

What is 15 minutes in billable hours?

Exactly 0.25 hours. A 6-minute chart has no 0.25, so 15 minutes becomes 0.3 under both the round-up and nearest-tenth rules. On a quarter-hour chart it is 0.25.

Should I round each entry or the total?

Follow your agreement or firm policy. In the example above, rounding each entry up gives 5.9 hours ($885.00) and rounding the total once gives 5.5 hours ($825.00) for the same 5:29 of work.

Why is time billed in 6-minute increments?

Because 6 minutes is exactly one tenth of an hour. Every entry becomes a one-decimal number that adds up and multiplies by a rate with no H:MM conversion, and the block is small enough to record a short call or email.

How many billable hours a day is 1,800 a year?

Over 50 weeks of 5 days, 7.2 hours a day, which is 7:12 on the clock.