The general math behind regular vs. overtime hours — not a substitute for your employer's specific pay policy.
Overtime rules — what threshold triggers it, what rate applies, and whether split shifts factor in differently — vary by employer, industry, and location, and they change over time. We're not going to tell you what your specific employer owes you. What we can do is walk through the general arithmetic that most hourly overtime systems use, so you understand how the numbers get produced. Always confirm your actual entitlement with your employer's HR/payroll team or a qualified professional.
With a split shift, start by calculating the hours worked in each individual shift, not the full span of the day. Subtract clock-in from clock-out for each shift separately.
Note that the unpaid gap between 12:00 PM and 4:00 PM (4 hours) is not counted — only the time actually worked goes into the total.
Add each day's total across the whole work week (most commonly Sunday through Saturday or Monday through Sunday, depending on how your employer defines a workweek).
The most common approach compares your weekly total against a weekly overtime threshold. In the US, 40 hours per week is the most common federal threshold for non-exempt hourly employees, though your employer, state, or union agreement may use a different number.
Some employers or agreements calculate overtime per day instead — any hours worked beyond a daily threshold (commonly 8) count as overtime for that day, regardless of how many total hours the week adds up to. This method catches a single unusually long day that a weekly-only calculation would miss.
Notice this is a different result than the per-week method would give for the same 42-hour week (2.0 OT hours either way here, but the two methods diverge quickly once daily totals vary more). Which method applies to you depends entirely on your employer's policy — this is exactly why Calculate My Hours lets you pick either mode rather than assuming one.
A common overtime multiplier is "time and a half" — 1.5× your regular hourly rate — applied only to the hours above the threshold. Whether this applies to you, and at what multiplier, depends entirely on your specific employment situation.
With two or three shifts per day, five to seven days a week, you're manually tracking and summing anywhere from ten to twenty individual time entries per pay period. A single transposed digit — writing 4:30 instead of 4:00 — throws off the daily total, which throws off the weekly total, which can push you over or under the overtime threshold without you noticing.