How to Calculate Night Shift Differential Hours

Night shift differential pay only applies to the hours that fall inside your employer's defined "night" window. Get this part wrong, and your whole pay calculation will be off — even if your math is otherwise correct. This guide walks through how to identify qualifying hours and calculate the pay for them.

Step 1: Find Your Employer's Night Shift Definition

There's no single legal definition of "night shift" — it's set entirely by your employer's policy or a union contract. The most common window is 6 PM to 6 AM, but some employers use 7 PM to 7 AM, 11 PM to 7 AM, or other ranges. Check your employee handbook or ask HR to confirm your specific window.

Step 2: Map Your Shift Against That Window

If your entire shift falls inside the night window, all your hours qualify. If your shift only partly overlaps — for example, a shift from 4 PM to midnight with a 6 PM to 6 AM night window — only the overlapping hours qualify for the differential.

Shift Time	Night Window	Regular Hours	Night Hours
4:00 PM – 12:00 AM	6:00 PM – 6:00 AM	2 hours (4–6 PM)	6 hours (6 PM–12 AM)

Step 3: Calculate Pay for Each Portion Separately

Once you know your qualifying hours, calculate regular pay for the daytime portion and differential pay for the night portion, then add them together.

Worked Example

David's split shift

David earns $21/hr with a 15% night differential for hours between 6 PM and 6 AM. He works 4 PM to midnight — 2 regular hours and 6 night hours.

Regular pay: 2 × $21 = $42.00
Night pay: 6 × ($21 + 15%) = 6 × $24.15 = $144.90
Total: $186.90

Step 4: Watch for Overtime Interactions

If any of your night hours are also overtime hours, the overtime rate must be calculated on your combined base-plus-differential rate, not your base rate alone. This is a federal requirement under 29 CFR § 778.207.

Common Mistakes to Avoid

Assuming your entire shift qualifies when only part of it falls in the night window
Forgetting to fold the differential into your overtime rate
Using the wrong night-shift time window because it wasn't confirmed with HR
Not accounting for rounding rules your employer's timekeeping system may apply

Skip the Manual Math

Use our free night shift calculator

Enter your rate, night hours, and differential, and get your exact pay breakdown instantly — including overtime.

Open Night Shift Calculator

Frequently Asked Questions

What time range usually counts as night shift?

Most employers define night shift as hours worked between roughly 6 PM and 6 AM, but the exact window is set by company policy or a union agreement, not by federal law.

What if my shift only partly overlaps with night hours?

Only the portion of your shift that falls inside the defined night window typically qualifies for the differential. You calculate regular pay for the daytime portion and differential pay separately for the night portion.

How do I find my exact night differential window?

Check your employee handbook, offer letter, or ask your HR or payroll department. If you're in a union, your collective bargaining agreement will specify the exact hours and rate.

This article is for informational purposes only and isn't legal or payroll advice. Confirm your specific pay policy with your employer or HR department.