Shift Differential Calculator
Worked a mix of day and night shifts? Your overtime is not 1.5× your base rate. Enter each shift and this calculator finds the FLSA weighted-average regular rate your employer is required to use.
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Free Blended Overtime Excel Template
Log a multi-rate week and get the blended regular rate, the half-time premium and total gross pay, with the 29 CFR 778.115 rule cited on the sheet. Keep it as your payroll record.
How shift differential overtime works under the FLSA
When you work at two or more rates in the same workweek, 29 CFR § 778.115 requires your employer to blend them into a single regular rate of pay before any overtime is calculated:
Overtime is then an additional half of that regular rate for every hour over 40 — the straight time for those hours is already inside the first figure. So the full overtime hour is worth 1.5× the blended regular rate, not 1.5× your base rate. This is the same weighted-average math behind any blended hourly rate.
Worked example: 48 hours across two shifts
You work 30 hours of day shift at $18.00/hr and 18 hours of night shift at $24.00/hr — 48 hours in one workweek, so 8 hours of overtime.
| Shift | Hours | Rate | Straight-time pay |
|---|---|---|---|
| Day | 30 | $18.00 | $540.00 |
| Night (+$6 differential) | 18 | $24.00 | $432.00 |
| Total | 48 | — | $972.00 |
- Regular rate: $972.00 ÷ 48 hours = $20.25
- Overtime premium: 8 hours × $20.25 × 0.5 = $81.00
- Total weekly pay: $972.00 + $81.00 = $1,053.00
An employer who paid the overtime premium off the $18.00 base rate instead would hand over $72.00 — $9.00 short every week, or $468 over a year. Multiply that across a shift-working department and it is why this is one of the most commonly cited FLSA violations.
Common shift differential structures
The FLSA does not require a differential at all — it is set by your employer, a union contract, or state law. These are the structures you will usually see:
| Shift | Typical differential | How it is usually expressed |
|---|---|---|
| Evening / 2nd shift | 5–10% | Percentage of base, or $1–2/hr |
| Night / 3rd shift | 10–15% | Percentage of base, or $2–4/hr |
| Weekend | 10–20% | Flat per-hour premium |
| On-call / hazard | Varies | Flat stipend per shift or week |
Whichever form it takes, it belongs in the regular rate. A flat weekly stipend gets divided across the hours you actually worked that week; a per-hour premium is simply part of that shift's rate.
Four mistakes that create back-pay liability
- Paying overtime at the base rate. The example above — the single most common error, and it always underpays.
- Paying overtime at the highest rate worked. Overpays, but still wrong, and it makes the payroll record unreliable if a claim is filed.
- Leaving a flat differential out of the regular rate. Non-hourly differentials are still remuneration for employment and are not excludable under § 207(e).
- Blending across the wrong period. The regular rate is calculated per workweek, never averaged across a two-week pay period.
One narrow exception exists: under FLSA § 7(g)(2) an employer may pay overtime at the rate in effect for the work actually performed during the overtime hours — but only under an agreement reached before the work is done. Absent that, the weighted average is mandatory.
Related calculators and guides
- Blended hourly rate calculator — the same weighted average for any mix of hourly rates.
- How to calculate a blended hourly overtime rate — step-by-step FLSA method.
- Blended overtime rate with two pay rates — the two-shift case worked end to end.
- FLSA weighted-average overtime — what § 778.115 actually requires of employers.
- Blended rate calculator — the general weighted-average tool.
- Blended tax rate calculator — what that overtime is worth after federal tax.
Frequently asked questions
How is shift differential overtime calculated under FLSA?
Under 29 CFR § 778.115, total straight-time earnings across all shifts are divided by total hours worked in the workweek to derive the regular rate. Overtime is paid at 0.5 times this regular rate for all hours over 40.
Why can't employers pay overtime at the day shift rate?
The Department of Labor requires weighting all non-overtime pay rates. Paying overtime at only the lower day-shift rate causes underpayment and FLSA violation penalties.
What is a typical shift differential?
Shift differentials are commonly 5% to 15% of base pay, or a flat amount such as $1 to $3 extra per hour for evening, night, or weekend shifts. The exact amount is set by the employer — the FLSA does not mandate a differential, but once one is paid it must be included in the regular rate for overtime.
Is shift differential pay included in overtime?
Yes. Shift differential pay must be folded into the regular rate before overtime is calculated. You divide total straight-time earnings (base plus all differentials) by total hours worked to get the regular rate, then pay 1.5 times that rate for hours over 40 — not 1.5 times the base rate alone.
How do I calculate my blended rate across two shift rates?
Multiply the hours at each rate by that rate, add the results, then divide by total hours. For example, 24 hours at $20 plus 16 hours at $23 is (480 + 368) ÷ 40 = $21.20 as your blended regular rate. This is the same weighted-average method used for any blended hourly rate.
Can an employer ever pay overtime at the shift rate instead of the blended rate?
Yes, in one narrow case. Section 7(g)(2) of the FLSA permits overtime based on the rate in effect for the work actually performed during the overtime hours — but only if the employer and employee agree to it before the work is performed. Without that prior agreement, the weighted-average regular rate is mandatory.
Does a shift differential count toward the regular rate if it is a flat weekly amount?
Yes. Whether the differential is a percentage, an extra amount per hour, or a flat sum for working an undesirable shift, it is remuneration for employment and belongs in the regular rate. Divide the flat amount across the hours worked in that workweek.
Scope. This calculator applies the federal weighted-average regular-rate method of 29 CFR § 778.115 to a single workweek and a 40-hour overtime threshold. It does not handle state rules that differ from the FLSA — notably California's daily overtime and double-time thresholds — nor the § 7(g)(2) election, bonuses that must be retroactively allocated, tip credits, or exempt classifications. It is not legal advice; for a pay dispute, consult an employment lawyer or the Department of Labor's Wage and Hour Division.
Just need the weighted average?
Skip the overtime rules and blend any set of hourly rates into one figure.