Shift Differential Overtime Calculator
Night-shift workers earn a differential, extra dollars per hour for working unpopular hours, and those dollars do double duty: they raise straight-time pay and they raise the overtime rate, because federal law folds the differential into the regular rate before computing time and a half. Most calculators ignore that second effect and underpay the overtime line. This shift differential overtime calculator does the full Fair Labor Standards Act math: straight-time earnings with the differential, the blended regular rate, the overtime premium, and the weekly total.
Quick Answer
At $24 an hour with a $3 night differential, working 24 day hours, 16 night hours, and 8 overtime hours pays $1,326 for the week. Straight-time earnings are $1,224, the blended regular rate is $25.50 an hour, the overtime premium is $102, and the differential itself is worth $72 a week ($3,744 a year).
- The differential raises your overtime rate, not just straight time. Because the regular rate blends all earnings, a $3 differential lifts the overtime premium from $96 to $102 in the example.
- The regular rate is total earnings divided by total hours. There is no shortcut: $1,224 over 48 hours is $25.50, and half of that times 8 overtime hours is the $102 premium.
- Differentials are employer policy, not federal law. The FLSA does not require shift differentials; it only governs how they interact with overtime once paid.
- The annual value adds up fast. $72 a week is $3,744 a year, before the overtime interaction, which is why night-shift premiums are worth negotiating.
The regular-rate math, step by step
The Department of Labor defines the regular rate as total earnings in the workweek divided by total hours worked, with shift differentials included in earnings. Here is the example worked through:
24 hrs x $24 plus 24 night hrs x $27: $1,224.
24 + 16 + 8 = 48 hours in the workweek.
$1,224 / 48 = $25.50 an hour.
0.5 x $25.50 x 8 = $102.
$1,224 + $102 = $1,326.
The key insight is in step 3: without the differential, the regular rate would be $24.00 and the premium $96. The $3 differential adds $6 to the premium on top of the $72 it adds to straight-time pay. That compounding is exactly what simple calculators miss when they compute overtime from the base rate.
Differential amounts compared
Same schedule (24 day, 16 night, 8 overtime hours) at a $24 base rate. Watch the premium column: it rises with the differential even though overtime hours never change.
| Differential | Straight-time pay | Regular rate | OT premium | Weekly total |
|---|---|---|---|---|
| $0 | $1,152 | $24.00 | $96 | $1,248 |
| $2 | $1,200 | $25.00 | $100 | $1,300 |
| $3 | $1,224 | $25.50 | $102 | $1,326 |
| $5 | $1,272 | $26.50 | $106 | $1,378 |
A $5 differential versus none is a $130 weekly difference: $120 in straight-time differential pay plus $10 of extra overtime premium. Over a year, that is $6,760. When comparing shift offers, always price the differential's overtime interaction, not just the hourly bump. Convert any weekly total to an hourly figure with our salary to hourly calculator, or see the after-tax picture with our hourly pay after taxes calculator.
Why the differential raises your overtime
It feels intuitive to compute overtime as 1.5 times the $24 base rate ($36 an hour, $288 for 8 hours), but that is not what the law requires when a differential is in play. The FLSA's regular rate captures "all remuneration for employment," which includes shift premiums. So the 8 overtime hours are really paid at 1.5 times $25.50 ($38.25), totaling $306: the $204 of straight-time value for those hours plus the $102 premium. The $18 difference between the naive and correct methods is small weekly, but it is a legal entitlement, and it compounds across a year of overtime.
Two caveats. First, this assumes the overtime hours were worked on the differential shift; if your overtime falls on day shift, only the day rate counts for those hours. Second, some employers pay daily overtime or double time under state law or union contracts, which this federal-model calculator does not cover. For plain overtime without differentials, our quarterly wage calculator annualizes any weekly figure.
What shift calculators get wrong
The near-universal error is computing overtime from the base rate while adding the differential only to straight-time hours, which silently underpays the premium. The second is treating the differential as a bonus added after overtime, which gets the total right by accident but teaches the wrong method and breaks the moment hours change. The third is ignoring the regular-rate concept entirely, so users cannot verify the number against their pay stub. This calculator shows every intermediate figure, straight-time earnings, blended regular rate, premium, so the math is auditable line by line.
A second week, worked through
Take a higher-paid night pattern: $30 an hour, a $4 differential, 20 day hours, 20 night hours and 10 overtime hours. The tool prices the 20 day hours at the base rate and the other 30 hours at $34, giving straight-time earnings of $1,620. Spread over 50 hours, the blended regular rate is $32.40 an hour, so the overtime premium on the 10 overtime hours is half that rate times 10, or $162. The week pays $1,782 in total.
The differential itself is worth $120 a week, or $6,240 over a year, which is 6.7% of the week's pay: enough to sit in the tool's "meaningful boost" band. The pattern repeats the Quick Answer lesson: overtime hours are paid at the differential rate first, and only then does the half-rate premium apply on top, because the regular rate already blends the differential in. For reference, the same 50 hours with no differential at $30 an hour would pay $1,500 in straight time plus a $150 premium, or $1,650 in total: $132 less than the differential week. If those 10 overtime hours had been day hours instead, both the straight-time base and the premium would fall. Try it in the calculator by moving hours between the day and night boxes.
Frequently Asked Questions
Extra hourly pay for working less desirable shifts: nights, weekends, or holidays. A $3 differential on a $24 base rate means night hours pay $27. Differentials are set by employer policy or union contract, not by federal law.
It raises the regular rate used for overtime. The differential dollars join total earnings before dividing by total hours, so the overtime premium (half the regular rate times overtime hours) grows. In the example, the $3 differential adds $6 to the weekly premium.
No. The FLSA does not require shift differentials; employers offer them to staff hard-to-fill shifts. But once paid, the differential must be included in the regular rate for overtime purposes.
Total straight-time earnings in the workweek divided by total hours worked. It blends base pay, differentials, and most non-discretionary bonuses into one hourly figure, which is then used to compute the overtime premium.
If the overtime is worked on the differential shift, yes: those hours earn base plus differential as straight-time value, plus the premium. Overtime on a non-differential shift earns only the base rate plus the premium.
No. Differential pay is ordinary wages: federal income tax, Social Security, Medicare, and state tax all apply exactly as they do to base pay. It is withheld as part of your regular paycheck, not at bonus rates.
Add This Calculator to Your Website
References
- U.S. Department of Labor, Wage and Hour Division. Fact Sheet #23: Overtime Pay Requirements of the FLSA. Accessed October 18, 2026.
- Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates. Accessed October 18, 2026.
- U.S. Bureau of Labor Statistics. Employer Costs for Employee Compensation News Release. Accessed October 18, 2026.
- Internal Revenue Service. Publication 15 (Circular E), Employer's Tax Guide. Accessed October 18, 2026.
- U.S. Bureau of Labor Statistics. Employment Cost Index News Release. Accessed October 18, 2026.