Billable hours, straight to an invoice
Log the week, set your rate, add GST if you are registered — then push every day across as an invoice line item without retyping a single number.
SOURCE·Arithmetic only — no external rate·REVIEWED JUL 2026
SOURCE·Arithmetic only — no external rate·Unpaid breaks deducted, midnight rollover applied·REVIEWED JUL 2026
What contractors get wrong about billable hours
Employees count the hours they were at work. Contractors have to count the hours they can defend, and the two are rarely the same number.
Round in consistent increments. Six-minute units (0.1 of an hour) are the professional-services convention; fifteen-minute units are normal in the trades. Pick one and use it everywhere — inconsistent rounding is what makes a client start checking your maths.
Describe the work, not the duration. "Consulting — Tuesday (09:00–17:00)" survives a review. "Hours: 8" invites a phone call. When you send this sheet to the invoice generator, each day carries its own description across for exactly that reason.
Bill promptly. Hours logged this week and invoiced this week get paid roughly a month sooner than hours invoiced at month end — and the detail is still fresh enough to answer any question about them.
Decimal hours or h:mm — the answer in both, and the gap between them
Time is base 60. Money is base 10. Every payroll error you have ever seen lives in the gap between those two facts.
If you work 8:45am to 5:15pm you have done 8 hours 30 minutes. Written down carelessly as 8.30 and multiplied by an hourly rate, that pays you for 8.30 hours instead of 8.5 — a loss of 12 minutes a day. Over a 46-week year that is close to a full working week of unpaid time, and it happens quietly because 8.30 looks right.
The fix is to convert once, properly: minutes ÷ 60. Thirty minutes is 0.5, not 0.30. The calculator above shows both formats for every row so you can copy whichever your payroll system wants and never do the conversion in your head.
How this is worked out
- A day is measured in whole minutes: finish minus start. Nothing is rounded at this stage.
- If the finish time is earlier than the start time, the shift is read as crossing midnight and a full day (1,440 minutes) is added — 22:00 to 06:00 is 8 hours, not minus 16. The row is labelled overnight so the assumption is visible. A finish time equal to the start is read as an empty entry, not a 24-hour shift; split a genuine 24-hour shift across two rows.
- The unpaid break, in minutes, is subtracted from that day. Paid rest breaks are entered as zero, because the hours that belong on a timesheet are the hours you are paid for. A break longer than the shift floors the day at zero rather than going negative, and the row is flagged.
- The week is the sum of the days in minutes, converted once at the end. Seven days rounded individually drift from the week's total; minutes summed and converted once cannot.
- Decimal hours are minutes ÷ 60 to two places; h:mm is the same minutes shown as whole hours and a remainder. Pay, where a rate is entered, is applied to the decimal total, and GST is added on top of that.
day = (finish − start) + (finish < start ? 1440 : 0) − unpaid break [minutes] week = Σ day [minutes] decimal = week ÷ 60 (2 dp) h:mm = ⌊week ÷ 60⌋ : (week mod 60)
Breaks, overnight shifts and the bits that trip people up
Unpaid breaks come off the total
Enter the break in minutes and it is deducted from that day. If your break is paid, enter zero — the number that belongs on a timesheet is the number of hours you are being paid for, not the hours you were on site.
In New Zealand, rest and meal breaks are set by law based on how long the work period is: a 10-minute paid rest break after two hours, and an unpaid 30-minute meal break after four. A standard eight-hour day therefore usually has 30 unpaid minutes in it, which is why the calculator defaults to 30.
Shifts that cross midnight
Enter 22:00 and 06:00 and the calculator adds the day rollover for you rather than returning a negative number. The row is labelled overnight so the assumption is visible — if you actually meant a 16-hour day, split it into two rows.
Billable hours are not worked hours
If you are a contractor rather than an employee, the number that matters is what you can defensibly put on an invoice. Round to sensible increments — six-minute (0.1 hour) units are the professional-services standard, fifteen-minute units are common for trades — and record what the time was spent on while you still remember. A line item that says "Consulting — Tuesday (09:00–17:00)" gets queried far less often than one that says "hours".
Minutes to decimal hours, in full
The conversion payroll systems want, for the awkward increments people get wrong. Fifteen is 0.25 and thirty is 0.5; it is the twenties and forties that cost money.
| Min | Decimal | Min | Decimal | Min | Decimal |
|---|---|---|---|---|---|
| 3 | 0.05 | 20 | 0.33 | 45 | 0.75 |
| 5 | 0.08 | 24 | 0.40 | 48 | 0.80 |
| 6 | 0.10 | 25 | 0.42 | 50 | 0.83 |
| 9 | 0.15 | 30 | 0.50 | 54 | 0.90 |
| 10 | 0.17 | 35 | 0.58 | 55 | 0.92 |
| 12 | 0.20 | 36 | 0.60 | 57 | 0.95 |
| 15 | 0.25 | 40 | 0.67 | 58 | 0.97 |
| 18 | 0.30 | 42 | 0.70 | 59 | 0.98 |
Turn the hours into money
Counting the time is step one. These do the rest, and the numbers carry across automatically.
Invoice these hours
Every worked day becomes a line item with your rate applied and GST calculated. One click, no retyping.
invoice.amit.marketing →Work out the GST
Add 15% to your total, or find the GST already sitting inside an agreed price.
gst.amit.marketing →Stop doing the tax admin
Hnry takes contractor income, pays the tax, ACC and GST, and files the returns automatically. Built for NZ self-employed.
See Hnry →Hours calculator FAQ
How do I calculate hours worked between two times?
How do I convert minutes to decimal hours?
Does it handle night shifts that cross midnight?
Should I take the break off before or after?
How many hours is full time in New Zealand?
Can I turn my hours into an invoice?
Is my timesheet saved?
Where these figures come from
Every number this tool uses, with the official source and the date it applies from. If a figure here is out of date, the source link is the one to trust.
- Paid rest breaks and unpaid meal breaks (Employment Relations Act 2000, Part 6D)
- Four weeks' paid annual holidays; 8% holiday pay in place of annual holidays (Holidays Act 2003)
Next after the hours calculator
Ranked by what people actually reach for next. Figures carry across — no retyping, no signup.
Hours are added up. Send them out as a GST tax invoice without retyping a line.
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JUL 2026See all 10 free tools in one list →
These tools are free and always will be. Built by Amit Sharma — an Auckland real-estate agent and marketer followed by 214K across YouTube, Facebook, Instagram and TikTok.