Updated October 22, 2026
This law firm billable hours calculator follows the hour all the way to the bank: hours at work, the share that is billable (utilization), the share of billable time that reaches an invoice (realization) and the share of invoices that get paid (collection). You get billable hours per year and per day, collected revenue, the effective rate you really earn per billable hour and per hour at work, the money lost along the way and the weekly billable hours a revenue goal requires.
Quick answer: Billable hours = hours at work per week × weeks × utilization. Collected revenue = billable hours × hourly rate × realization × collection. Effective rate = hourly rate × realization × collection. Billable hours needed for a goal = revenue goal ÷ effective rate.
An estimate from the numbers you entered, not a market price. Put in your own costs for a number you can stand behind.
Owners spend about 11 to 16 hours/week on admin, and a lead reached within an hour is nearly 7 times more likely to turn into a real conversation (HBR). The math is the easy part; the money leaks out in the calls you can't take, the follow-ups nobody sends and the invoices that sit unpaid. Unmanually is a 24/7 AI Office Manager for law firms that you run by voice from your phone:
Sources: admin hours, Time etc / Censuswide 2023 and Amex SME Barometer 2026; speed to lead, HBR audit of 2,241 US companies (2011).
We send these exact numbers to your inbox in a few seconds, with a link that reopens the calculator with them filled in.
Email only. We use it to send your breakdown and follow up about Unmanually. Unsubscribe any time.
Unmanually is an AI Office Manager that works 24/7 and that you run by voice from your phone. Leave your mobile number and the AI Office Manager calls you right away, the same way it would call back someone asking about a consultation for a new matter. That call is the demo: it answers, books you a 15-minute time with the founder and follows up.
We use your details only to call you and follow up about Unmanually. Unsubscribe any time.
billable hours = hours at work per week × weeks × utilizationvalue of billable time = billable hours × standard hourly rateinvoiced = value × realization; collected = invoiced × collectioneffective rate = hourly rate × realization × collectionbillable hours for a goal = revenue goal ÷ effective ratebillable hours per week for the goal = hours needed ÷ working weeks
These are assumptions for illustration, not benchmarks. Swap in your own numbers from your time and billing records.
A lawyer at work 50 hours/week for 48 weeks, with 60% utilization, a $300 standard rate, 88% realization and 93% collection, and a $400,000 collected revenue goal.
Hours at work: 50 × 48 = 2,400. Billable: 2,400 × 60% = 1,440 hours, 6 per working day. That time is worth 1,440 × $300 = $432,000. After 88% realization, $380,160 is invoiced; after 93% collection, $353,549 is collected. The effective rate is $300 × 0.88 × 0.93 = $245.52 per billable hour, or $147.31 per hour at work. $78,451 of worked value never arrives.
The $400,000 goal needs $400,000 ÷ $245.52 = 1,629 billable hours, or 33.9/week. Raising collection from 93% to 98% alone brings the collected revenue to $372,557 without one more hour.
Every hour at work leaks three times before it is money in the account. Utilization is the share of hours that are billable and recorded. Realization is the share of that time that ends up on an invoice after write-downs and discounts. Collection is the share of invoices clients actually pay. Multiply them and the result is usually far below the standard rate. Clio publishes yearly figures for all three in its Legal Trends benchmarks, if you want to compare with other firms.
Intake calls, returning messages, scheduling, chasing documents and admin eat the day. Some of it is billable and never recorded; much of it is not billable at all. Recording time as you go, instead of at the end of the week, catches more of it. Handing the intake calls, reminders and document chasing to staff or software frees hours for billable work.
Time that is written down at billing, discounted for a client or never entered at all lowers realization. Clear engagement letters, budgets agreed up front and regular billing (monthly rather than at the end of the matter) help clients accept the invoice.
Unpaid invoices age quickly. Prompt invoicing, online payment, reminders at set intervals and retainers or evergreen deposits keep collection up. A few points of collection are often worth more than a rate increase, and clients don't notice them.
For predictable matters, flat fees shift the focus from hours to efficiency. Use this calculator to sanity-check a flat fee: estimate the hours, multiply by your effective rate and compare. Track the hours on a few flat-fee matters anyway; it is the only way to know which ones make money and which fees need to rise.
Run the calculator for each lawyer and paralegal, then add them up. Differences in utilization between people usually point to who is carrying the intake and admin load.
People with a legal problem call several firms and retain the one that answers and books a consultation. Unmanually is an AI Office Manager that works 24/7 and that you run by voice: the AI Office Manager answers, takes the intake questions you set for each practice area, books the consultation and texts the confirmation, sends reminders, then sends invoices and chases them. See what Unmanually does for law firms, or get a free website that calls every new lead back in about a minute.
What the AI Office Manager does for law firms, from intake calls to collections.
Why slow intake loses retained clients.
Practical ways to bring in more matters.
Pricing calculators and templates for every trade.
Multiply hours at work per week by working weeks, then by utilization, the share of those hours that are billable and recorded. 50 hours × 48 weeks × 60% = 1,440 billable hours.
Realization is the share of the value of billable time that makes it onto invoices. Collection is the share of invoiced amounts that clients pay. Both reduce what an hour is really worth.
The standard rate × realization × collection. At $300 with 88% realization and 93% collection, the effective rate is $245.52 per billable hour.
Divide the goal by your effective rate. In the worked example, $400,000 needs about 1,629 billable hours, or 33.9/week over 48 weeks.
Bill regularly, agree budgets in engagement letters, record time as you go, offer online payment, send reminders on a schedule and use retainers. Track both rates monthly to see what works.
Pick the one that fits where your business is right now.
$99/month
Your AI Office Manager calls back every lead, books the job and runs your office 24/7, so hours of admin become minutes of talking.
Start Growth$0, no credit card
A website for your business that makes your phone ring, built in 60 seconds. Add the Growth plan whenever you are ready.
Get my free website