Time Card Calculator

It looks for an am or pm suffix at the end of what you typed (line 37); if you write a plain 24-hour value like 17:30 with no suffix, it's read literally as 5:30 PM. The one special case is 12 o'clock: 12 AM is read as midnight, hour zero, and 12 PM stays at noon, hour twelve, rather than both mapping to the same hour (lines 57-59).

No. Which hours fall into the Regular, Overtime, or Double-Time bands is decided entirely by the Overtime Rule and the times you entered, before either multiplier is ever used (lines 138-177); the two multipliers only scale how much each of those already-decided hours is worth in the pay calculation (line 189), so raising the Overtime Multiplier changes Overtime Pay but never changes Overtime Hours.

Federal applies a single weekly test set by the Fair Labor Standards Act (29 CFR Part 778): every hour beyond 40 in the week is overtime, no matter how it's spread across days (lines 167-177). California Labor Code Section 510 layers daily thresholds on top of that -- over 8 hours in a single day is overtime and over 12 is double time -- and adds a premium for a seventh consecutive day worked in the week, with the weekly 40-hour test still applied afterward to whatever hours are still counted as regular (lines 138-166), so the same schedule can produce more paid overtime under California's rule.

Effective Hourly Rate is Gross Pay divided by Total Hours, and dividing by zero would normally produce an undefined or infinite result; the calculator checks for that case directly and reports zero instead whenever Total Hours is zero (line 203), so a blank time card shows a clean $0 rather than an error or a nonsensical figure.

Saturday and Sunday start with no clock-in or clock-out entered, so worked time for that day is already zero and a break can't subtract from it. It's collected and doesn't currently affect the total until you also enter hours for that day, at which point it behaves like any other day's break.