Prorated Bonus Calculator
Bonuses usually assume you were there for the whole ride: the full year, the full quarter, the full bonus period. Real careers are messier. People join in March, leave in October, or take unpaid leave in between, and in all of those cases a fair bonus is the full amount scaled down to the time actually worked. That scaled amount is the prorated bonus, and the math is one clean fraction: full bonus times time worked divided by the total bonus period.
The calculator below handles both common conventions. Use months for the simple version most HR policies describe, or switch to days when you need precision, for example for contract staff or short tenures. It also shows the share of the bonus you earned and the amount left on the table, so there is no ambiguity for either side of the payroll desk.
| Share of full bonus earned | 0.0% |
| Forfeited (unearned) amount | $0.00 |
| Calculation | — |
Leave the period blank for the standard 12 months (or 365 days). Time worked beyond the period is capped at the full bonus.
Quick Answer
For a $10,000 annual bonus with 9 of 12 months worked, the prorated bonus is $7,500.00: 75.0% of the full amount, with $2,500.00 forfeited. On a daily basis, a $6,000 bonus with 180 of 365 days worked pays $2,958.90. The calculator handles both conventions and shows the forfeited remainder alongside the payout.
Key takeaways
- Prorated bonus = full bonus × (time worked ÷ bonus period). One fraction, nothing else.
- Months match most HR policies; days suit mid-month starts and short tenures. The two can give slightly different answers, so use one consistently.
- Time beyond the period never pays extra: the tool caps the result at the full bonus.
- Blank and negative inputs are treated as zero, not flagged, so double-check your entries before trusting the number.
- Quick Answer
- How to use the prorated bonus calculator
- The formula: one fraction, two conventions
- Worked example, checked against this exact tool
- What the tool does with edge cases
- Months or days: which should you use?
- Why your bonus check is smaller than the math
- What competing calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the prorated bonus calculator
Enter the full bonus, how long you worked, and how long the period is, then click Calculate. The results stay hidden until you do.
- Enter the full bonus amount: the gross figure for working the entire period, from your offer letter or plan document. $10,000 is pre-filled as the worked example.
- Pick the calculation basis: months for the standard HR version, days when you need precision. The input labels switch to match.
- Enter time worked and the total period: 9 of 12 months is pre-filled. For a quarterly bonus, use 3 as the period with the months worked that quarter; the period can be left blank for the 12-month (or 365-day) standard.
- Read all three lines: the payout, the share of the bonus you earned, and the forfeited remainder, plus the calculation spelled out so you can check it.
If your bonus itself is built from salary × target percent × a performance rating, run the bonus salary calculator first to get the full amount, then prorate it here for the partial period. This page is the pure time-fraction tool: it starts from a bonus figure you already know.
The formula: one fraction, two conventions
Prorated bonus = full bonus × (time worked ÷ total bonus period). The only judgment call is the unit, and it changes the answer.
Months: $5,000 × (5.5 ÷ 12) = $2,291.67 | Days: $5,000 × (169 ÷ 365) = $2,315.07
| Basis | When to use it | Watch out for |
|---|---|---|
| Months | Standard HR policies, annual and quarterly bonuses, simple cases | Months are not equal length, and mid-month starts need a rounding rule |
| Days | Mid-month starts, short tenures, contract staff, precise splits | Agree on 365 vs 366 in a leap year, and count consistently |
The $5,000 example above assumes someone who joined on July 15 with a calendar-year bonus period: 5.5 of 12 months by the months convention, 169 of 365 days by the days convention. Same person, same bonus, a $23.40 difference, which is why the worked-example section below pins down one convention per calculation. Pick the one your plan document names; when it is silent, months are simpler and days are fairer.
Worked example, checked against this exact tool
A $10,000 annual bonus, 9 of 12 months worked. Every figure below is a real run of the calculator above; enter the same inputs to reproduce them.
The same tool, run on more shapes of the same problem:
| Inputs | Prorated bonus | Share earned | Forfeited |
|---|---|---|---|
| $10,000, 9 of 12 months | $7,500.00 | 75.0% | $2,500.00 |
| $6,000, 180 of 365 days | $2,958.90 | 49.3% | $3,041.10 |
| $8,000, 14 of 12 months | $8,000.00 | 100.0% | $0.00 |
| $1,000,000, 11.5 of 12 months | $958,333.33 | 95.8% | $41,666.67 |
A 13th-month bonus is the special case of this same arithmetic where the period is the full year and the convention is fixed by statute or contract; the 13th month salary calculator covers that variant directly.
What the tool does with edge cases
This calculator never scolds you: it coerces odd inputs into sensible defaults instead of showing errors. That keeps it fast, but it means a blank form quietly returns $0.00, so know the rules before trusting a number.
| Input | What the tool does |
|---|---|
| Blank or non-numeric field | Treated as zero. A fully blank form returns $0.00 with no warning. |
| Negative bonus | Clamped to $0. The share earned still reflects time worked, so check the payout line, not just the percent. |
| Time worked beyond the period | Capped at the full period: 14 of 12 months pays the full $8,000.00, never more. |
| Blank or zero period | Falls back to the standard: 12 months, or 365 days in days mode. |
Months or days: which should you use?
Match your plan document first. When it is silent, the trade-off is simplicity against fairness.
Months
- Matches how most companies write bonus policies, so disputes are rarer.
- Simple mental math: 9 of 12 is obviously three quarters.
- Mid-month starts need an agreed rounding rule, or someone feels short-changed.
Days
- Precise to the day: fair for short tenures, contract staff, and mid-month starts.
- No month-length distortions; every day of service counts equally.
- You must agree on the denominator: 365, or 366 in a leap year.
Whichever you choose, use it for everyone in the same cycle. Mixing conventions across employees is how payroll disputes start.
Why your bonus check is smaller than the math
The calculator gives the gross bonus. Your paycheck withholds tax first, and bonuses are withheld differently from salary.
The IRS treats bonuses as supplemental wages. Under IRS Publication 15, an employer paying the bonus separately from regular wages withholds a flat 22% for federal income tax, rising to 37% on supplemental wages above $1 million from that employer in the calendar year. Withholding is not your tax rate: your actual tax is your marginal rate when you file, and any over-withholding comes back as a refund. State withholding and Social Security and Medicare taxes apply on top, so the check that lands is always smaller than the calculator’s number.
What competing calculators miss
Most prorated bonus pages are articles with the formula and no working tool, or tools that cover only one convention and stop at the payout.
- Savvy Calculator’s prorated bonus tool: the closest direct rival, months-only with a performance multiplier. No daily mode, no forfeited line, and no disclosure of how it handles blanks or over-period time.
- Salary.com’s prorated bonus guides: the day-count method explained carefully, with new-hire and early-termination examples. But there is no interactive tool: you do the arithmetic yourself, and the pages funnel toward compensation software.
- Formula-only guides (info-tech, dollarsandsense and similar): useful worked examples, including the months-versus-weeks-versus-days comparison that shows the convention changes the answer. Again, no tool, and some are written for one country’s payroll rules.
- The gap this page fills: months and days in one tool with the labels switching to match, the forfeited remainder shown next to the payout, edge-case behavior disclosed in a table instead of hidden, and every worked example reproducible to the cent. It sits in a family of proration tools here: prorated billable hours for client work and prorated days off for PTO use the same time-fraction logic on different quantities.
Frequently asked questions
A partial bonus payment scaled to the time you actually worked during the bonus period. If you join mid-year or leave early, you receive the full bonus multiplied by the fraction of the period you worked.
Months are simpler and match most company policies. Days are more precise and suit contract staff, mid-month starts, or short tenures. Pick one method and use it consistently, since the two can give slightly different results: on a $5,000 bonus, 5.5 of 12 months gives $2,291.67 while 169 of 365 days gives $2,315.07.
The calculator caps time worked at the total period, so the result never exceeds the full bonus. Overtime beyond the period does not create extra bonus; 14 of 12 months still pays the full amount.
Blank or non-numeric fields are treated as zero with no warning, so an empty form returns $0.00. A blank period falls back to the standard 12 months (or 365 days). Double-check your entries before trusting the number.
It depends on your contract, company policy, or collective agreement, and on local labor law. Federal law sets minimum wage and overtime rules but does not mandate bonuses, so check what your employment terms actually promise.
Yes. Enter the quarterly bonus amount, set the basis to months, and use 3 as the total period, with the months you worked during that quarter.
Prorated bonuses are computed from the gross bonus amount stated in your compensation terms, before tax withholding. Bonuses can also factor into overtime calculations for hourly workers, which is another reason plans start from gross.
The calculator gives the gross bonus; your employer withholds tax before paying it. Bonuses are supplemental wages: 22% flat federal withholding when paid separately, 37% above $1 million in a year, plus state withholding and payroll taxes. Withholding is not your final tax rate; the difference settles when you file.
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References
- Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide: supplemental wages. Accessed October 23, 2026.
- Internal Revenue Service. Publication 15-T (2026), Federal Income Tax Withholding Methods. Accessed October 23, 2026.
- U.S. Department of Labor, Wage and Hour Division. Fact Sheet #56A: Bonuses and the Regular Rate of Pay under the FLSA. Accessed October 23, 2026.
- U.S. Department of Labor, Wage and Hour Division. The Fair Labor Standards Act (FLSA): minimum wage, overtime, and coverage. Accessed October 23, 2026.
- U.S. Department of Labor. Severance Pay: federal law does not require it; agreements govern. Accessed October 23, 2026.