Prorating a salary means paying an employee a fair share of their monthly compensation for the days they actually worked. It comes up constantly in HR — when someone starts on the 12th, resigns on the 22nd, or switches between full-time and part-time mid-month. Payroll teams choose between two main methods, each with different math, legal context, and employee-relations implications.
The two proration methods and when to use each
The workday (260-basis) method is the most common in the United States for salaried exempt employees. It divides the annual salary by 260 — representing 52 weeks of five-day workweeks — to get a daily rate, then multiplies by the number of Monday–Friday days worked. This method is consistent across months: the daily rate never changes regardless of how many workdays fall in a given month. Payroll systems that run bi-weekly (26 pay periods) or semi-monthly (24 pay periods) typically align with this convention.
The calendar-day method divides the monthly base (annual ÷ 12) by the total calendar days in the month and multiplies by days worked, including weekends. This approach is more common in jurisdictions with employment laws that define a salaried day as a calendar day, in hourly-to-salary conversions, or when a company wants full-month pay to always equal exactly one-twelfth of the annual salary — which the workday method does not guarantee.
Which method produces a higher paycheck?
It depends on timing. If most of the days worked are weekdays (employee starts Monday, leaves Friday), the workday method typically pays more because it credits only the days the employee was actually in the office. If the worked period spans many weekends — for instance, an employee works the 1st through the 8th of a month, which includes a full weekend — the calendar method credits those weekend days and often produces a higher result.
For full months, the workday method is not always exactly one-twelfth of the annual salary. February (often 20 workdays) produces less than the December equivalent (also 23 workdays), while months with 23 workdays (like August in some years) produce more than the monthly average of 21.67 workdays. Companies that want predictable equal monthly pay choose the calendar method for exactly this reason.
Legal considerations and employer obligations
The Fair Labor Standards Act (FLSA) does not specify a proration method for salaried exempt employees, so employers have discretion. However, your written employment policy or offer letter governs the calculation — if the offer says 'monthly salary of $X,' many employees and courts interpret that as the calendar-day method. If it says 'annual salary payable bi-weekly,' the workday method is more defensible. Always document which method you use in your employee handbook and apply it consistently to avoid wage-claim disputes.
For non-exempt (hourly) employees, proration works differently: FLSA requires overtime on hours worked over 40 per week, so the prorated amount for a partial week must account for actual hours, not just days. This calculator is designed for salaried exempt employees only.