How ClockSlate works
Calculation Methodology
ClockSlate is designed to make work-time calculations transparent, repeatable and easy to check. This page documents the rules used by version 0.2, last reviewed on September 3, 2026.
Who creates and reviews the calculators
ClockSlate is an independently built utility site. Calculator requirements, formulas, edge cases, copy and release results are checked against documented test cases and representative manual examples. AI-assisted development is used to accelerate research, implementation and testing; it does not replace release review or the published formulas.
Core calculation rules
Clock times and elapsed time
Valid clock times are converted to minutes after midnight. When an end time is earlier than its start time, calculators that support overnight work treat the end as occurring on the next day.
Breaks
An unpaid break is deducted after elapsed time is calculated. A break cannot be negative or longer than its shift. Paid breaks are not deducted because they already count toward worked time.
Decimal hours
Decimal hours are a fraction of 60 minutes, not clock-style minutes. The displayed value is rounded to the precision selected by the user, while calculations retain the underlying minute or second value.
Time rounding
The time-card calculator does not round by default. When selected, each clock-in and clock-out event is rounded to the chosen increment and direction before the shift duration is calculated. Break minutes are not rounded.
Overtime and estimated pay
Regular hours are capped at the user-entered weekly threshold. Hours above that threshold are classified as overtime. A biweekly card evaluates Week 1 and Week 2 separately. Estimated pay multiplies regular and overtime hours by the values entered by the user.
Testing approach
Automated tests cover parsing, 12- and 24-hour formatting, midnight boundaries, rounding directions, weekly overtime splits, pay calculations, declared routes, canonical sitemap URLs and required assets. Release QA also checks rendered HTML, response status, security headers, keyboard-accessible form labels and common mobile layouts.
Representative cases include 12:00 AM and PM, compact entries such as 855 and 1730, overnight shifts, zero-length entries, breaks longer than shifts, biweekly overtime that must not be averaged, fractional-hour conversion and negative duration arithmetic.
Privacy and data handling
Live calculations run in the visitor's browser. Calculator entries are not submitted to ClockSlate. If a visitor explicitly saves preferences, those settings are stored in that browser. Share links encode the selected time-card values in the URL fragment, which browsers do not send to the web server as part of a normal request.
Limitations
- ClockSlate does not decide which employment, overtime, break or rounding law applies.
- Pay estimates exclude taxes, deductions, benefits, premiums and rules not explicitly entered.
- Generated results and spreadsheet templates should be checked against source records before payroll use.
- Time zones and daylight-saving transitions are not applied to manually entered clock times.
Corrections and updates
Calculation defects, unclear assumptions and accessibility issues are treated as product bugs. Please contact ClockSlate with the calculator, input values, expected result and observed result so the case can be reproduced.