How do I bill 37 hours 45 minutes of development work at an hourly rate?
Enter the quantity in decimal hours: 45 minutes is 0.75 of an hour, so the quantity is 37.75, and the unit price is your hourly rate. The classic slip is typing 37.45, which quietly undercharges you.
Why 37.45 is wrong
An hour has sixty minutes, not a hundred. In the quantity field, 37.45 means 37 hours and 45 hundredths of an hour, which is only 27 minutes. The field has no idea about hours and minutes; it reads an ordinary decimal and multiplies it by the price.
The rule is to divide the minutes by 60. A quarter hour is 0.25, half an hour 0.5, 45 minutes 0.75, and 20 minutes roughly 0.333333.
The example, run through the tool
A developer billing a Dubai company at 180 AED an hour logged 37 hours 45 minutes this month and typed 5 in the rate field, because that is the rate he charges in his situation. This is what the Basic invoice generator produces:
Line: API development, September, quantity 37.75, hourly rate 180.00
Line total: 6,795.00 AED
Tax (5%): 339.75 AED
Total: 7,134.75 AED
Type 37.45 instead and the line comes out at 6,741.00, fifty-four dirhams less before tax. Small on one invoice, but it repeats every month once it becomes a habit.
From timesheet to invoice
If you log start and end times every day, total them first in the Timesheet calculator, then convert the total to decimal hours and carry it into the quantity field. To make it clearer for the client you can:
- Write the original time in the line description: 'Development, 37 h 45 min'.
- Split the work into several lines by task, each with its own hours.
- Attach the timesheet when the client wants the detail.
Rounding details worth knowing
The tool reads quantities exactly to six decimal places, and each line total is rounded to the nearest fils or halala, with halves rounded up. So if you enter 20 minutes as 0.333333, the line is rounded after the multiplication, not before. Tax is then worked out on the discounted subtotal and rounded to the smallest unit as well. Agreeing with the client to bill in quarter hours keeps the numbers tidy and easy for both sides to check.