The 6-Minute Law Firm Billing Chart: Tenths of an Hour Decimal Conversion & Retainer Math
A reference standard for paralegals, associates, and managing partners on 6-minute billing intervals, ethical rounding guidelines under ABA Model Rule 1.5, and retainer trust accounting.
1. The Universal 6-Minute Legal Billing Conversion Chart
Most law firms in the United States record billable attorney time in increments of one-tenth of an hour (0.1 hours = 6 minutes). This convention simplifies mathematical multiplication when applying hourly billing rates.
1 to 6 minutes = 0.1 Hours | 7 to 12 minutes = 0.2 Hours | 13 to 18 minutes = 0.3 Hours | 19 to 24 minutes = 0.4 Hours | 25 to 30 minutes = 0.5 Hours | 31 to 36 minutes = 0.6 Hours | 37 to 42 minutes = 0.7 Hours | 43 to 48 minutes = 0.8 Hours | 49 to 54 minutes = 0.9 Hours | 55 to 60 minutes = 1.0 Hours.
2. The Mathematical Billing Formula
To programmatically convert raw minutes into decimal hours for billing software (Clio, MyCase, PracticePanther, TimeSolv), software developers and billing managers utilize the ceiling formula: Decimal Hours = Math.ceil(Minutes / 6) / 10.
3. Ethical Rounding Under ABA Model Rule 1.5
Under American Bar Association (ABA) Model Rule of Professional Conduct 1.5, a lawyer shall not collect an unreasonable fee or an unreasonable amount for expenses.
Rounding up is permissible within standard billing increments, but "block billing" (lumping multiple tasks into a single 4-hour block) or routinely billing 0.2 (12 minutes) for a 30-second email is heavily scrutinized by fee arbitration committees and court bankruptcy audits.
4. IOLTA Retainer Trust Account Rules
Retainer fees paid upfront by clients are unearned legal fees that must be deposited into an Interest on Lawyers’ Trust Account (IOLTA). An attorney cannot transfer funds from the IOLTA trust account to the firm’s operating account until services are formally rendered and an itemized invoice is generated.
Frequently Asked Questions
What is the minimum billable time increment in law firms?
The standard minimum time increment in most corporate and litigation law firms is 0.1 hours (6 minutes). Even a 2-minute phone call is billed as 0.1 hours, provided the client retainer agreement explicitly authorizes this practice.
What is the difference between a true retainer and an advance fee deposit?
A true retainer is a non-refundable fee paid solely to reserve the attorney’s availability and conflict them out of representing opposing parties. An advance fee deposit is money held in trust that is drawn down only as hourly legal work is performed.