Money
Prorate Calculator
Last updated: May 31, 2026
Written by Blake Boege
A prorate calculator is a financial utility that determines the proportional charge or payment of a recurring amount over a partial period. It divides the total amount for a full period by the number of days in that period to establish a daily rate, and multiplies it by the number of active or occupied days. It is widely used to calculate partial-month rent, subscription refunds, or mid-period salary adjustments.
Prorate rent, salaries, utility bills, or subscriptions. Enter the full-period rate, the number of total days in the period, and the number of active days to determine the proportional amount owed.
Quick Answer
Calculate the proportional cost of rent, a subscription, or salary for a partial billing cycle. Enter the full rate, period days, and active days.
Billing Details
The rent, subscription, or salary amount for a full billing period.
Total calendar days in the full period (e.g. 28, 30, 31).
The number of days you actually use or occupy the service (cannot exceed total days).
Prorated amount
$650.00
Based on 13 of 30 active days
Examples
$1,500 rent, 30-day month, move in on the 18th (13 active days)
Prorated Rent: $650.00
$2,000 subscription, 31-day billing, 10 active days
Prorated Cost: $645.16
$1,200 rent, 28-day February, 5 unoccupied days (23 active days)
Prorated Rent: $985.71
How it works
Prorating is calculated by dividing the total period rate by the number of total days in that period to establish a daily rate, and then multiplying that daily rate by the active days of use:
Daily Rate:
Daily Rate = Total Amount ÷ Total Days in Period
Prorated Cost:
Prorated Amount = Daily Rate × Active Days
Remaining Balance (Refund/Discount):
Remaining Amount = Total Amount − Prorated Amount
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Frequently asked questions
Prorating means to allocate an amount proportionally over a partial period. For example, if you move into an apartment halfway through the month, you only pay for the days you occupy it. The monthly rent is prorated by dividing the rent by the number of days in the month, then multiplying by your active days.
Divide the full period price (such as monthly rent or annual salary) by the total number of calendar days in that billing period. For rent, this is typically 28, 29, 30, or 31 days depending on the specific month.
Usually yes, but some landlords or rental agreements use a standard 30-day month for all calculations, or an average of 30.42 days (365 days ÷ 12 months) to standardise billing. It is best to check your lease agreement.
Yes. For salaries, you can divide your annual rate by 365 (or 260 working days, depending on employer policy) to find the daily rate, then multiply by the active days in the partial pay period.
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