Calcoid

Shift Calculator

Total worked hours across a rotating shift schedule. Compare DuPont, Pittman, Continental, 4-on-3-off, or a custom on/off pattern. Returns hours per week, month, and year, days off per year, weekends off, night-shift count, and the federal and state overtime thresholds.

Shift schedule

Pick a preset or choose custom to enter your own on/off rhythm.

Hours per week

42 hr

Hours per month

182.6 hr

Hours per year

2,192 hr

Cycle length
28 days, 14 shift(s)
Hours per cycle
168 hr
Shift length
12 hr
Hours per 4-week projection
168 hr
Days off per year
183 days
Weekends off per year
~26 weekends
Night shifts per cycle
7 shift(s)

Schedule notes

DuPont: fourteen 12-hour shifts across a 28-day rotating day-and-night cycle, including a 7-day break. Averages 42 hours per week and about 183 days off per year.

Overtime: Federal: covered nonexempt employees generally earn overtime after 40 hours in a workweek. Alaska and California generally add daily overtime after 8 hours. Colorado generally adds it after 12 hours in a day or 12 consecutive hours. Nevada's 8-hour daily rule depends on pay rate and exceptions. Verify current rules and worker classification.

Frequently Asked Questions about the Shift Calculator

Is the DuPont preset the traditional DuPont rotation?
Yes. It models the traditional DuPont rotation as a 28-day aggregate with 14 12-hour shifts across day and night blocks. It calculates hours and long-run days off, but it does not generate the day-by-day roster. Verify dates against your employer's schedule.
Why do preset weekly averages differ?
The calculator divides worked shift hours by the selected cycle length and scales that value to seven days. The DuPont preset uses 168 hours across 28 days, or 42 hours per week. Compare the preset aggregate with your actual roster before using it for payroll.
When does daily overtime kick in for a 12-hour shift?
The calculator reports schedule hours and does not determine overtime. Federal, state, industry, exemption, union, and alternative-workweek rules can all affect when overtime starts. Check current labor guidance and your agreement before converting the schedule into pay.
How accurate is the days-off-per-year estimate?
The estimate multiplies the off-day share of the cycle by 365.25 and rounds. It is a long-run average, not an exact count for a particular calendar year or roster start date. PTO, holidays, swaps, training, and partial cycles are not included.
Can I model a 24-hour-on schedule like firefighters use?
You can model a simple 24-hours-on, 48-hours-off cycle with custom values of 1 day on, 2 days off, and a 24-hour shift. That pattern is not a complete representation of every Kelly, platoon, relief-day, or Section 7(k) schedule. Use the employer's full cycle for staffing or pay decisions.

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