Pro Rata Calculator
Calculate a prorated amount for a partial period
Frequently Asked Questions
Pro rata amount = full amount × (partial period ÷ full period). For example, $1,500 monthly rent (a 30-day month) prorated for 20 remaining days is $1,500 × (20 ÷ 30) = $1,000.
Common uses include prorating rent when moving in or out mid-month, prorating a subscription fee when upgrading or canceling partway through a billing cycle, prorating salary for a partial pay period, and prorating annual fees or insurance premiums for a partial term.
Use whatever the underlying agreement specifies — many leases and subscriptions prorate using actual calendar days in that specific month, while some contracts use a flat 30-day month regardless of the actual days. Check your specific agreement.
Yes — enter your full pay period's salary as the full amount, the full number of working days in that pay period, and the number of days actually worked to get the prorated salary.
Yes — switch to "By dates" mode and enter the full billing period's start/end dates and the partial period's start/end dates. The calculator counts the actual calendar days for you, which avoids off-by-one mistakes from manual counting.