About the Time Card Calculator
A time card calculator computes total hours worked in a week from clock-in and clock-out times, handling breaks, overtime, and conversion to decimal hours for payroll. Even simple weekly totals can produce errors by hand because time arithmetic is base-60 (60 minutes per hour, 24 hours per day) — and U.S. wage-and-hour rules add complexity around unpaid breaks, overtime thresholds, and rounding policies.
The math: time to decimal hours
Payroll systems work in decimal hours, not hours and minutes. 7:30 (seven hours, thirty minutes) becomes 7.5 decimal hours. The conversion: minutes ÷ 60. So 7 hours 15 minutes = 7 + 15/60 = 7.25 hours; 8 hours 45 minutes = 8.75 hours.
Calculating shift duration: end time minus start time, with attention to breaks (typically subtracted from total) and shifts crossing midnight (add 24 hours to end time before subtracting). 8:30 AM to 5:30 PM with a 30-minute unpaid lunch: 9 hours total, 8.5 hours paid.
Federal overtime rules
Under the Fair Labor Standards Act (FLSA), non-exempt employees must be paid at least 1.5× their regular rate for hours worked over 40 in a single workweek. Workweek is defined by the employer (typically Sunday–Saturday or Monday–Sunday) but must be a fixed, regularly recurring period.
Overtime is calculated weekly, not daily — at the federal level. So an employee working 12 hours Monday and 4 hours Tuesday accrues no overtime if the weekly total stays at or under 40 hours. Some states (notably California and Alaska) impose daily overtime requirements: California requires 1.5× pay over 8 hours/day and 2× over 12 hours/day, regardless of weekly total.
Exempt employees (most salaried workers in executive, administrative, professional, and certain other categories under FLSA exemptions) are not entitled to overtime. The legal definition of 'exempt' is specific — being paid a salary doesn't automatically make someone exempt. Misclassification of non-exempt workers as exempt is a major source of wage-and-hour lawsuits.
Breaks and rest periods
Federal law (FLSA) doesn't require meal or rest breaks for adult employees. Many states do — e.g., California requires a 30-minute unpaid meal break after 5 hours and a 10-minute paid rest period for every 4 hours worked. Required breaks can change the math of the time card meaningfully; missed-break penalties in some states can add an hour of pay per missed break.
Short breaks (typically 5–20 minutes) are generally counted as paid working time under federal law. Meal breaks of 30+ minutes are typically unpaid if the employee is fully relieved of duty. An employee who eats at their desk while still answering calls is technically still working — those breaks are paid time, even if labeled as 'lunch'.
Rounding and recordkeeping
FLSA permits rounding clock-in/out times to the nearest 5, 6, or 15-minute increment, as long as it's done neutrally (not always in the employer's favor). The 'seven-minute rule' — round to the nearest quarter-hour, with the cutoff at 7 minutes — is widely used. Employees who clock in at 8:07 are recorded as 8:00; at 8:08, as 8:15.
Recordkeeping requirements: federal law requires employers to keep payroll records for 3+ years. State laws often require longer retention (4–6 years). Best practice: keep dated, accurate clock-in/out records and reconcile them monthly. Time-card disputes years later are easier to resolve with contemporaneous records than with reconstructed estimates.
Formula
- Regular hours = Up to 40 in a workweek (federal FLSA threshold)
- Overtime hours = Hours over 40 in a workweek (or as defined by state-specific daily rules)
- Rate = Hourly base rate (or salary ÷ standard hours for salaried non-exempt)
Worked examples
Standard 40-hour week
Mon–Fri, 8:00 AM to 5:00 PM with 30-minute unpaid lunch each day. Per day: 8.5 hours. Week: 42.5 hours. At $20/hour: 40 × $20 + 2.5 × $30 (1.5× overtime) = $800 + $75 = $875 gross.
Shift crossing midnight
Start 11:30 PM Monday, end 7:30 AM Tuesday. End time + 24 = 31:30. Duration: 31:30 − 23:30 = 8:00. Decimal: 8.0 hours. Multi-day workweeks need attention to which day each shift counts toward for the workweek total.
California daily overtime
10-hour shift on a single day: 8 hours regular + 2 hours overtime (1.5× rate). 14-hour shift: 8 hours regular + 4 hours overtime (1.5×) + 2 hours double time (2×). California's daily overtime applies even if the weekly total is below 40 hours — meaningful additional cost for employers and additional pay for employees on long days.
Frequently asked questions
How do I calculate hours worked from clock-in and clock-out?
Subtract clock-in from clock-out, accounting for unpaid breaks. Convert to decimal hours: minutes ÷ 60. For shifts crossing midnight, add 24 hours to the clock-out time before subtracting. Example: 8:00 AM to 5:30 PM with 30-min unpaid lunch = 9 hours total, 8.5 hours paid = 8.5 decimal hours.
When does overtime kick in?
Federal: hours over 40 in a workweek for non-exempt employees, paid at 1.5× regular rate. Some states add daily overtime: California (1.5× over 8/day, 2× over 12/day), Alaska, Nevada, Colorado (in some industries). Check state rules — they often supplement, not replace, the federal rule.
Are breaks paid or unpaid?
Federal law: short breaks (5–20 min) are typically paid; meal breaks (30+ min, fully relieved of duty) are typically unpaid. State laws often require specific paid or unpaid breaks. An employee who's still on call or working through a 'break' is still working — that time is paid regardless of the label.
Is overtime calculated daily or weekly?
Federal: weekly. Hours over 40 in a workweek trigger overtime, regardless of how distributed across days. Some states impose daily overtime (notably California). For employees in those states, both daily and weekly overtime rules apply — the higher of the two calculations governs final overtime pay.
How do salaried employees get paid for overtime?
Salaried employees who are 'non-exempt' under FLSA must still receive overtime when working over 40 hours/week. Their hourly rate for overtime calculations is salary ÷ hours that the salary is intended to cover. Salaried employees who are 'exempt' under FLSA executive/administrative/professional definitions don't get overtime — but the exemption requires meeting specific legal tests, not just being paid a salary.
Can my employer round my clock-in time?
Yes, within limits. FLSA permits rounding to 5, 6, or 15-minute increments as long as it doesn't systematically favor the employer. The 'seven-minute rule' (round to nearest quarter-hour) is widely accepted. Rounding rules that consistently shave time only off the employee's side violate FLSA and have been the basis of class-action wage-and-hour lawsuits.