About

Time theft and manual calculation errors cost the global economy billions annually. For freelancers, consultants, and hourly employees, the difference between a rough estimate and a precise calculation can mean hundreds of dollars in lost revenue per month. This Work Hours Calculator is an industrial-strength utility designed to bridge the gap between simple clock-watching and professional payroll processing. It eliminates the ambiguity of manual time arithmetic, specifically addressing the pain points of sexagesimal conversion (minutes to decimals) and midnight crossover (shifts spanning two calendar days).

Unlike basic counters, this tool implements a Double-Ledger Logic. It simultaneously tracks physical time duration for health/compliance (fatigue management) and billable financial value for invoicing. It creates an audit trail for your week, allowing you to reconcile worked hours against billed hours instantly. The system creates a persistent local state, meaning your data remains secure on your device without requiring server-side storage or user accounts, ensuring 100% privacy for sensitive wage data.

Formulas

The core engine uses a 24-hour modulus arithmetic system to handle shift continuity. The Gross Duration (D_gross) is calculated first.

{

D_gross = t_out − t_in if t_out > t_inD_gross = (24 + t_out) − t_in if t_out < t_in (Overnight)

Net Billable Hours (H_net) are derived by subtracting unpaid break intervals (B). The system converts minutes to floating-point hours:

H_net = (D_gross × 60) − B_min60

Total Revenue (R) applies the Overtime Multiplier (M) to hours exceeding the statutory limit (L).

R = (min(H_net, L) × rate) + (max(0, H_net − L) × rate × M)

Reference Data

Minute Segment	Decimal Equivalent (h)	Standard Efficiency Impact	Billing Practice (Round Up)
1 - 5 min	0.02 - 0.08	Micro-task / Email	IGNORE or 0.25
6 - 12 min	0.10 - 0.20	Short Call / Triage	0.25
15 min	0.25	Standard Unit	0.25
20 min	0.33	Pomodoro Cycle	0.50
30 min	0.50	Meeting Slot	0.50
45 min	0.75	Deep Work Session	0.75 / 1.00
60 min	1.00	Hourly Rate Base	1.00
90 min	1.50	Ultradian Rhythm Limit	1.50

Frequently Asked Questions

Yes. The interface allows for infinite shift addition per day. Click "+ Add Shift" on any specific day to create a secondary time block. The system automatically aggregates these into the daily total while preserving the individual start/end times for the CSV export.

The logic detects "Midnight Crossover". If you Clock In at 22:00 (10 PM) and Clock Out at 06:00 (6 AM), the calculator recognizes that the end time is numerically smaller than the start time and automatically attributes the duration to the next calendar day, resulting in an 8-hour shift rather than a negative error.

No. This tool operates on a "Local-First" architecture. All hourly rates, times, and calculations are stored in your browser's LocalStorage. No data leaves your device, ensuring privacy for sensitive payroll information.

Yes. The "Export CSV" feature generates a structured file compatible with Excel, Google Sheets, and standard accounting software. It includes columns for Date, Start/End times, Break Duration, Total Hours, and Estimated Earnings.

By default, the break field is 0. If you leave it empty, the system assumes continuous work. We recommend entering breaks to ensure the "Net Billable Hours" reflect your actual contract terms.