Billing Increment Calculator NZ
This billing increment calculator converts the minutes you spent on a task into the billable units that go on an invoice, and the amount those units come to at your hourly rate. Time billed in fixed units rather than exact minutes is easier to read on an invoice, and the six-minute unit is especially convenient because each one is exactly a tenth of an hour: three units are 0.3 hours, eight units are 0.8 hours, and the invoice line needs no further conversion. The calculator also handles units of 10, 15, 30 and 60 minutes. Whatever the unit, a task that does not fill a whole number of units has to be rounded, and the direction matters: rounding up bills slightly more than the time spent, rounding down slightly less, and rounding to the nearest can go either way. You enter the minutes, choose the unit and the rounding, and enter your hourly rate. The calculator shows the units billed, the time they represent in decimal hours, the amount to bill, the amount for the exact minutes and the difference the rounding makes. The unit and the rounding are commercial terms you agree with your client, not rules this page sets. The table further down converts every minute from 1 to 60 into six-minute units.
From the same team as Calculate.co.nz
Your Timesheets at jobtracker.co.nz logs your hours on a week grid or a timer that keeps counting when your phone locks, free on every plan. Career and Timesheets turns those hours into projects and rates, fixed fees and retainers, numbered invoices with GST only when you are registered, expenses and mileage, and the tax to set aside, from $4.99 a month billed yearly.
Log your hours freeHow it works
The minutes are divided by the unit. Rounding up takes the next whole number of units, rounding down the last whole one, and rounding to the nearest whichever is closer, with an exact half rounding up. The units multiplied by the unit length give the minutes billed, and dividing by 60 gives decimal hours. The amount billed is those hours at your rate, and the amount for the exact minutes is the time you actually spent at the same rate. The difference between the two is what the rounding adds, or takes away when it is negative. Each line of an invoice is rounded on its own, so the effect across a week depends on how many separate entries you record.
Six-minute units for 1 to 60 minutes, rounded up
| Minutes spent | Units | Decimal hours | Amount at $250 an hour |
|---|---|---|---|
| 1 to 6 | 1 | 0.1 | $25.00 |
| 7 to 12 | 2 | 0.2 | $50.00 |
| 13 to 18 | 3 | 0.3 | $75.00 |
| 19 to 24 | 4 | 0.4 | $100.00 |
| 25 to 30 | 5 | 0.5 | $125.00 |
| 31 to 36 | 6 | 0.6 | $150.00 |
| 37 to 42 | 7 | 0.7 | $175.00 |
| 43 to 48 | 8 | 0.8 | $200.00 |
| 49 to 54 | 9 | 0.9 | $225.00 |
| 55 to 60 | 10 | 1.0 | $250.00 |
Worked example
A task takes 47 minutes and is billed in six-minute units, rounded up, at $250 an hour. 47 divided by 6 is 7.83, which rounds up to 8 units: 48 minutes, or 0.8 hours. At $250 an hour that is $200.00. Exactly 47 minutes at the same rate would be $195.83, so rounding up adds $4.17. Rounding down instead would bill 7 units, 0.7 hours and $175.00. The same task rounded up under each unit:
| Unit | Units billed | Minutes billed | Amount | Added by rounding |
|---|---|---|---|---|
| 6 minutes | 8 | 48 | $200.00 | $4.17 |
| 10 minutes | 5 | 50 | $208.33 | $12.50 |
| 15 minutes | 4 | 60 | $250.00 | $54.17 |
| 30 minutes | 2 | 60 | $250.00 | $54.17 |
| 60 minutes | 1 | 60 | $250.00 | $54.17 |
Related calculators
- Timesheet Rounding Calculator: the effect of rounding every entry across a week and a year.
- Decimal Time Converter: hours and minutes to decimal hours and back.
- Hours to Decimal Calculator: convert a time such as 7:30 to 7.5 hours.
- Realisation Rate Calculator: how much of your standard rate you actually bill and collect.
- Invoice Calculator: billed hours to an invoice total with GST and withholding tax.