Legal Billable Hours Calculator

Billable hours tracking is essential for law firms, consultants, accountants, and any professional who bills clients by time. Accurate tracking directly determines revenue.

Basic billing formula: Invoice Amount = Hours Worked × Hourly Rate

For partial hours (using decimal notation): 15 minutes = 0.25 hours 30 minutes = 0.50 hours 45 minutes = 0.75 hours

Monthly revenue from billable hours: Monthly Revenue = Billable Hours per Month × Hourly Rate

Effective hourly rate (accounting for non-billable time): Effective Rate = Monthly Revenue ÷ Total Hours Worked (billable + non-billable)

Worked example: An attorney bills 120 hours in a month at $350/hour. Monthly Revenue = 120 × $350 = $42,000

They actually worked 160 total hours (40 hours were admin, business development, and internal meetings). Effective Rate = $42,000 ÷ 160 = $262.50/hour effective rate

Utilization rate: Utilization % = (Billable Hours ÷ Total Hours Worked) × 100

Example: 120 billable hours out of the same 160 worked: Utilization = (120 ÷ 160) × 100 = 75%

Industry benchmarks:

• Large law firm associate: 1,800–2,200 billable hours/year
• Average lawyer: 1,500–1,800 billable hours/year
• Target utilization rate: 75–85% is the figure consulting firms quote. Law firms set an annual hours target instead, and 1,800 billable hours against a 50-hour week comes to about 69%, so the two benchmarks are not measuring the same thing.

Realization rate: Realization % = (Amount Collected ÷ Amount Billed) × 100 Not every hour billed is paid. Write-offs, discounts, and non-payment reduce actual collected revenue. Industry average realization: 85–92%.

Why the effective rate is the number that matters

Nobody quotes their effective rate, and everybody quotes their hourly rate. The gap between the two is where a practice quietly loses money. Take the $350/hour attorney above. Their effective rate is $262.50, and at 85% realization, the low end of the industry range, the cash that actually lands is closer to $223. That is a third off the headline figure, and none of it shows up on an invoice. The calculator uses that same 85% so the two agree.

Two habits close most of the gap. Record time as you go rather than reconstructing Friday afternoon from your calendar, because reconstructed time is always short. And bill in six-minute increments (0.1 hour), the standard unit in US legal billing, rather than rounding everything to the quarter hour.

Rounding conventions and what they cost the client

At $350/hour that same call is $35 under six-minute billing and $175 under half-hour billing. Clients notice, and a billing dispute costs more in write-offs than the rounding ever gained. Ask which increment an engagement letter uses before you sign it.

This page starts from hours you have already recorded. To go the other way, from a weekly hours figure and a utilization percentage to what the year comes to, use the billable hours tracker. It has no retainer or realization step, but on the same hours and rate the two agree on the effective rate to the cent.