The rate difference
First, the calculator measures the gap between the hourly rate that was used and the corrected one. Every part of the retro adjustment builds on that gap.
Free U.S. retro pay calculator
Retro Pay: what a backdated hourly raise is worth
See the pay difference when a raise or rate fix takes effect before payroll starts using it. Enter the rate that was paid, the rate that should have applied, and every affected workweek on its own line to get straight-time retro pay plus the added federal overtime adjustment for hours beyond 40.
Runs in your browser. Hourly rates, weekly hours, and the retro amounts it produces stay on this page while you work.
Set the old rate beside the corrected rate
The tool is deliberately narrow: it handles an upward correction to a single hourly rate on pay that was otherwise figured at that one rate. Put each affected workweek on its own line so federal overtime hours are never averaged across weeks.
Backdated hourly-rate adjustment
Modeled retro pay, all weeks—
The rate difference across every hour entered, plus the added half-time adjustment the raise creates on federal overtime hours.
Rate increase per hour—
Retro per straight-time hour—
Retro per overtime hour—
Hours affected—
Federal overtime hours—
Workweeks entered—
Weeks with federal overtime—
Straight-time adjustment—
Added overtime adjustment—
Modeled pay at the old rate—
Modeled pay at the corrected rate—
How the figures were reached
—Why overtime is treated on its own
In a simple rate fix, the hourly difference applies to every affected hour. Because overtime hours also earned an extra half of the regular rate in this model, they pick up an added half-time adjustment based on the raise.
Week by week
| Week | Hours | Hours past 40 | Straight-time adj. | Added overtime | Retro total |
|---|
Stays in your browserThe rates and hours you enter never leave the calculator.
Week by weekFederal overtime hours are judged separately for every week you enter.
One focused fixBuilt for a simple backdated raise to a single hourly rate.
The simple rate-fix formulasRate increase = corrected rate − old rate
Straight-time adjustment = rate increase × every affected hour
Added federal overtime adjustment = 0.5 × rate increase × hours past 40 in each workweek
Straight-time adjustment = rate increase × every affected hour
Added federal overtime adjustment = 0.5 × rate increase × hours past 40 in each workweek
Why not just multiply the raise by all the hours?
That gives the straight-time difference, but it can come up short on a simple federal overtime correction whenever someone worked more than 40 hours in an affected week. The per-week half-time adjustment captures the higher regular rate on those overtime hours.
Retro pay in plain terms
What retro pay means when pay is corrected
Retro pay usually means pay for an earlier period that is paid later. A familiar case is a raise, a negotiated increase, or a rate fix that takes effect before payroll starts using the new hourly rate.
Weekly overtime
Federal overtime is generally judged one workweek at a time, not by averaging hours over a longer pay period. That is why each affected week is entered separately.
Effect on the overtime rate
With a single rate, each overtime hour gets the ordinary rate difference plus another half of it, which comes to 1.5 times the raise for that hour.
A good fit
The tool works best when the facts are simple and the real question is what a higher hourly rate, applied going back, adds up to.
- a raise that was made retroactive;
- an hourly increase that payroll missed;
- a fix for an hourly rate that was keyed in wrong;
- a single base hourly rate across the affected weeks;
- weeks where the overtime question is the federal hours-beyond-40 rule.
Reach for a broader calculator when pay is more complicated
A plain rate-difference model falls short when the regular rate depends on extra pay or on more than one rate.
- Try the Weighted Overtime Calculator for several hourly rates, includable bonuses, commissions, or other pay earned in the week.
- Try the Bonus Overtime True-Up when a deferred includable bonus has to be spread back over earlier workweeks.
- Try the Shift Differential calculator for night, evening, weekend, or other shift premiums.
Worked example
Example: a $2 hourly fix in a 45-hour week
Say payroll used $20 an hour, but the right rate was $22 an hour for a week in which 45 hours were worked. The hourly gap is $2.
Straight-time adjustment
$2 × 45 hours = $90. The gap applies to every hour that week, including the straight-time part already built into the overtime hours.
Added overtime adjustment
The week has 5 federal overtime hours, so the added half-time is 0.5 × $2 × 5 = $5.
Modeled retro pay in total
$90 + $5 = $95. Put another way, each of the 5 overtime hours earns $3 more — the $2 rate gap plus a $1 half-time adjustment.
How the federal method works, with official sources
29 CFR § 778.303 covers retroactive pay increases and explains that such an increase raises the regular rate for the retroactive period. The U.S. Department of Labor’s Field Operations Handbook likewise says retroactive increases paid for services belong in the regular rate and are assigned to the earlier workweeks they relate to. DOL Fact Sheet #23 sets out the basic federal rule: covered nonexempt employees generally earn overtime for hours beyond 40 in a workweek, and hours are not averaged across workweeks.
Sources last checked: August 30, 2026. This is an arithmetic model, not legal advice, and it does not decide FLSA coverage or exemption status. State, local, collective-bargaining, contract, industry, minimum-wage, and special overtime rules can change how pay must be handled.
Limits of the result
What the result shows — and what it can’t
A sound retro-pay figure depends on the facts you enter and on the pay rules that apply to the worker and the week.
It can help you
- see what a backdated hourly raise adds up to in dollars;
- keep the straight-time rate difference apart from the added federal overtime adjustment;
- spot which affected weeks went past 40 hours;
- print a week-by-week breakdown of the arithmetic for review or your records.
It does not decide
- FLSA coverage or exemption for the worker;
- the reach of state daily-overtime, double-time, spread-of-hours, reporting-time, or similar rules;
- any effect a union or individual contract has on the rate or overtime method;
- whether bonuses, commissions, premiums, or other pay must go into the regular rate;
- tax withholding, deductions, penalties, interest, damages, or deadlines for paying wages.
Common questions
Retro Pay: questions answered
How the arithmetic model works, and when a fuller payroll review may be needed.
What exactly is retro pay?
It is pay for an earlier period that arrives later. Here, it means the difference that results when a higher hourly rate is applied to workweeks that were already paid at a lower rate.
Are retro pay and back pay the same thing?
People often use the two terms loosely, but they can carry different legal or administrative meanings depending on context. The calculator doesn’t draw that legal line; it only models a specific hourly-rate correction for hours already worked.
How do I figure retro pay on an hourly raise?
Take the old rate away from the corrected rate and multiply the difference by the affected hours. For any affected week with federal overtime hours, add the overtime adjustment the higher rate creates on those hours.
Why does each workweek have to be entered on its own?
The basic federal overtime rule looks at hours one workweek at a time. A 50-hour week followed by a 30-hour week does not count as two 40-hour weeks when deciding whether the first week had federal overtime.
How does a backdated hourly raise change overtime?
Federal guidance says a retroactive increase raises the regular rate for the retroactive period. In this page’s simple single-rate model, the rate gap applies to every hour, and one more half of that gap is added for hours past 40 in each affected week.
Will it handle bonuses or commissions?
Not as a full calculation. Deferred bonuses and commissions may need to be spread back to the weeks that earned them, and several hourly rates may call for a weighted regular rate. Use the Bonus Overtime True-Up or the Weighted Overtime Calculator for those.
Does it cover state overtime or late-payment penalties?
No. State daily overtime, double time, local rules, late-payment penalties, liquidated damages, interest, minimum-wage fixes, and other remedies are outside it. The overtime part is limited to the basic federal hours-beyond-40 workweek model.
Does the result show the payroll was compliant?
No. It is an arithmetic scenario built from the numbers you enter. It does not settle coverage, exemption status, rate classification, payment timing, contract duties, or compliance with federal, state, or local law.
Are my rates and hours saved?
The math runs in your browser. Hourly rates, weekly hours, and the resulting retro amounts are not sent to a PayStubCheck server for calculation. Analytics only record usage details that aren’t pay figures, such as how many weeks were entered and whether any week had federal overtime.