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Calculation details
Planning estimate only. Pay, overtime, holidays, and working-time rules vary by employer and jurisdiction.
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What does this calculator estimate?
Shift differential calculator: compute extra pay for night, weekend, or holiday shifts by percentage or flat rate per hour. Free, no signup, runs locally.
How this calculator works
Formula
Shift pay = hours x base rate + hours x base rate x differential % + overtime hours x rate x multiplier.
Worked example
An 8-hour shift at $24/hr with a 10% differential: $192 base + $19.20 premium = $211.20 gross shift pay.
Frequently asked questions
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Cite this tool
BoringToolsKit. “Shift Differential Calculator.” boringtoolskit.com/shift-differential-calculator/. Free to reference in articles, syllabi, and answer posts with a link.
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Worked example: a 44-hour week at $20 with an 8% night differential
Enter 44 total hours, 4 overtime hours, a $20.00 base rate, an 8% differential, and a 1.5x overtime multiplier. The calculator first splits the week: overtime is the smaller of 44 and 4, so 4 hours, leaving 40 regular hours.
Regular base pay is 40 x $20.00 = $800.00. The shift premium applies only to that base, not to overtime: $800.00 x 0.08 = $64.00. Overtime pay layers all three factors: 4 hours x $20.00 x 1.5 = $120.00, then the differential stacks on top as x 1.08, giving $129.60. Total estimated gross shift pay is $800.00 + $64.00 + $129.60 = $993.60.
The stacking order matters for your paycheck. If your employer instead pays overtime on the pre-differential rate and adds the differential only to regular hours, the same week pays $120.00 in overtime rather than $129.60, a $9.60 gap. If the differential is defined as a flat dollar amount per hour rather than a percentage, the premium would be 44 x $1.60 = $70.40 on regular-plus-overtime hours instead of $64.00, and overtime would not compound. Compare this page's output against one actual pay stub before trusting it for a specific workplace; collective bargaining agreements and company policy define the stacking, not the FLSA.
Boundary cases the formula handles, and where it stays silent
The formula clamps hours with Math.max(0, hours) and caps overtime at total hours via Math.min, so entering 6 overtime hours against 40 total hours treats all 40 as overtime and reports $0.00 in regular base pay. Negative hours also floor to 0 rather than producing negative pay.
The differential input is the one place with no guard. At 0%, the premium line reads $0.00 and overtime collapses to hours x rate x multiplier; a $20/1.5x/4-OT-hour week pays $1,280.00 flat. A negative differential, such as -5, is accepted as written and subtracts: base pay shrinks by 5% and each overtime hour pays rate x 1.5 x 0.95, so a 'night penalty' style shift works arithmetically even though most US shifts are structured the other way.
Two real-world patterns the formula does not model. First, differentials tiered by shift (say 5% evenings, 10% nights) need you to run the calculator once per tier and add the results. Second, some employers pay a flat $/hour differential that does not scale with base rate and is excluded from the overtime regular rate under their policy; in that case the overtime line here overstates pay by the multiplier times the differential share. Weekly caps, hazard pay, and double-time tiers above 1.5x are likewise out of scope: enter the multiplier you actually receive and treat the output as one week's gross estimate, not annualized wages.