Billable hours calculator

Revenue from billable work is three numbers multiplied together: billable hours per week, working weeks per year, and your hourly rate. The catch for an accounting or bookkeeping practice is that the headline figure and the collected figure are rarely the same. The gap between them is realization, and ignoring it is how a practice that looks fully booked still misses its revenue target.

A worked example

Take the defaults. You bill 25 hours a week across 48 working weeks, after vacation and holidays. That is 1,200 billable hours a year. At $150 an hour, you bill $180,000 on paper. Apply a 90 percent realization rate for the time that gets written down, and you actually collect $162,000 a year, or $13,500 a month. Your effective rate is not $150 but $135 an hour once the write-down is counted. That $18,000 difference is the cost of unbillable admin and slow clients, and it is invisible until you put realization in the math.

The realization view matters most during busy season, when hours are capped by the calendar rather than by demand. When you cannot add hours, the only levers left are the rate and realization. A practice at 80 percent realization is giving away one day in five; moving to 90 percent is worth more than a rate increase for many firms, and it costs the client nothing.

The reverse calculation

The more useful question is often the other way around: what rate do you need to reach a revenue goal? The reverse view takes a target and divides it by your collected billable hours, which are your total billable hours multiplied by your realization rate. With the same 1,200 hours at 90 percent realization, a $180,000 target needs a rate of about $166 an hour, not $150, because the write-down has to be covered by the rate you set. Raise realization to 95 percent and the required rate drops. This is why realization is worth measuring: it changes the price you have to charge to hit the same number.

Where realization actually leaks

For accounting and bookkeeping practices, the write-down rarely comes from underpricing the work itself. It comes from the surrounding friction: chasing clients for documents, re-requesting the same files, fixing incomplete intake, and time spent on onboarding that never makes it onto an invoice. Tightening scope in a signed engagement letter removes one source. Moving intake, document collection, e-signatures, and payment into one structured client flow removes another. Portico handles that intake-to-payment flow on a single client link, so recovered hours go back to billable work rather than follow-up email. If you would rather do the arithmetic by hand, a spreadsheet with these four inputs gives the same numbers.