Shift differential calculator
Enter your base rate, your differential as dollars per hour or a percentage, and the hours you worked at each rate this workweek. The calculator finds your weighted-average regular rate, applies the overtime premium to it, and shows how much you lose if your employer computes overtime on the base rate alone. Built for nurses, warehouse and manufacturing workers on nights and weekends.
How to use this calculator
- Enter your base hourly rate.
- Enter the differential and choose whether it is dollars per hour or a percentage of base. The differential rate is shown underneath.
- Enter the hours you worked at base rate and at the differential rate this workweek.
- Read the weighted regular rate, the overtime premium on hours over 40, and the gross estimate.
- If you worked overtime, the red line shows how much you are underpaid when the premium is computed on the base rate only.
How a shift differential changes your overtime rate
A shift differential is extra pay for working certain hours, typically nights or weekends, either as a flat amount per hour or a percentage of your base rate. Under the Fair Labor Standards Act it is part of your regular rate of pay (29 CFR 778.108, 778.207). Because overtime is one and one-half times the regular rate, not the base rate, the differential raises your overtime rate.
When you work at two rates in one workweek, the regular rate is the weighted average: total straight-time pay at both rates divided by total hours (29 CFR 778.115). Overtime hours are then owed an extra half of that rate on top of the straight-time pay already earned. An employer who pays the differential on straight time but computes the overtime premium on the base rate alone is underpaying every overtime hour.
A worked example
A nurse earns $30 an hour with a 10 percent night differential ($33). In one workweek she works 24 hours on days and 24 hours on nights, 48 hours total. Straight-time pay is 24 x $30 + 24 x $33 = $1,512. The regular rate is $1,512 / 48 = $31.50. The 8 overtime hours earn an extra 0.5 x $31.50 = $15.75 each, or $126, for a gross of $1,638.
If the employer computes the premium on the $30 base rate, the premium is $120 and the nurse is short $6 for the week. Small per week, but it compounds across every overtime week of the year, and it is the kind of systematic error wage claims are built on.
What the calculator does not do
It applies the federal weekly threshold of 40 hours. For daily overtime in California and other daily-rule states, enter per-day hours in the overtime calculator. It treats the differential as nondiscretionary, which is the normal case; a truly discretionary bonus is excluded from the regular rate (29 CFR 778.211). It does not handle alternative workweek schedules or union agreements that provide a higher rate.
Frequently asked questions
Is shift differential included in overtime pay?
Yes. Shift differentials are part of the regular rate under 29 CFR 778.108, and overtime is 1.5x the regular rate. If you worked nights and overtime in the same week, your overtime rate must reflect the differential.
How is overtime calculated with two different rates?
By the weighted average in 29 CFR 778.115: add up straight-time pay at each rate, divide by total hours to get the regular rate, then pay an extra half of that rate for each hour over 40.
What is a typical night shift differential?
Flat amounts of a few dollars an hour or percentages around 10 to 15 percent are common in healthcare and manufacturing, but there is no legal minimum. The differential is set by your employer or contract.
My employer pays the differential but calculates overtime on base pay. Is that legal?
Not under the FLSA if the differential is a regular part of your pay. The overtime premium must be based on the regular rate including the differential. Use this calculator to quantify the gap, keep your punches, and raise it with payroll or your state labor agency.
Does a percentage differential change the math?
No. The calculator converts a percentage to a dollar rate (base x (1 + percent)) and then applies the same weighted-average method.
Does the weekend differential apply to overtime on the weekend?
The differential is paid for the hours it covers. Overtime depends on total weekly hours, not the day. If weekend hours push you over 40, those hours earn the differential rate for straight time plus the half-time premium on the weighted regular rate.
Related calculators
This calculator produces estimates for your own records. It is not payroll, tax or legal advice. Overtime rules vary by state, industry and employer policy. Sources: U.S. Department of Labor, 29 CFR Parts 516, 778 and 785; state labor codes named above.