Why are my rates off by a penny?

When looking at your rates you might notice that they are off by a penny or have many decimal places. Why does this happen? How come Projector can't just show the correct rate? Please visit the appropriate section of this page for an explanation of why you are seeing back calculated rates. For example, go to the Reports section if you are looking at rates in a report.


On an invoice you can show either a back calculated rate or what we call a nominal rate. The back calculated rate can have penny differences. Here is an example of that.

Given this equation: hours * rate = client amount. Hours and Client Amount are constants. Only rate can change.

  • Your rate is $133.33 per hour
  • You work 0.5 hours
  • Your billable cost is 133.33 * 0.5 = 66.665
  • Projector rounds this up to $66.67

Full stop. Why did we choose to round at this point? Because accounting systems do not accept fractional pennies. Now going forward, Projector is calculating rates using this rounded number! Take a look at the equation below and you can see that we are now off by a penny from our original $133.33.

  • Billing Rate = 66.67 / 0.5 = $133.34

Our first iteration of invoices always used back calculated rates. Our updated invoices use nominal rates. If you are a customer from before August 2017 then your templates use back calculated rates. If you are a customer after that date your templates use nominal rates. You can edit your templates to switch between the two methods.

Projector Web

When viewing rates in Projector Web, the behavior is exactly the same as with invoices. We back calculate rates. You can optionally included Nominal Rates in your query fields to see the natural rate.


When viewing rates in reports you may find that they are off by very small amounts. As with invoices, the reason is because we are back calculating rates based on the total hours and revenue. However, unlike with invoices we carry as much precision as possible. So you will notice that your rates may be precise to as many as 16 decimal places. The reason for back calculating in reports is because of pivot table aggregation. If we brought in exact rates, then as data was aggregated to higher and higher levels you would likely see larger and larger discrepancies in your reporting data. By using a calculated rate that is as precise as possible we truly minimize these issues. Combined with the fact that most currencies aren't viewed with more than two decimal places of precision, you are unlikely to run into problems with this in your reports.

If you need the original rate, not back-calculated, then look for the fields Nominal Billing Adjusted Rate or Nominal Contract Rate. Keep in mind that if you are aggregating data as opposed to looking at individual time cards, you could end up with rates being over or understated.

Expense Reports

You are much more likely to see small fluctuations in displayed rates for expense reports vs. other places in Projector. That is because ER rates are accurate to four decimal places. So the likelihood of being off by 1/10,000 is pretty good. Just as with invoices though, this is merely a display issue. You can rest assured that the correct rates were used for the forward calculation.

In expense entry, the behavior can seem weird. Resources will use the default rate, say 0.4540 per mile, but the back calculated rate ends up being 0.4543. They'll fix, save, and it again reverts. Both values give the same incurred amount and thus are accurate for billing purposes. You will need to cope with the display of the odd looking rate until we improve this part of the product.

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