Prorate a bill by days used: enter the full billing-period amount and days used (30-day cycle by default) to get the prorated charge or unused credit.
Prorated Bill Formula
The following formula is used to calculate the Prorated Bill.
Day-count example: AT&T’s billing guide describes its fixed 30-day convention. Other contracts may use actual cycle days or different rules. This calculation estimates the proportional amount; it does not establish a right to a refund.
- Where PB is the Prorated Bill ($)
- MB is the monthly bill amount ($)
- Du is the number of days used in the month
- Dm is the billing-period day count under the applicable contract
Multiply the full-period bill by days used, then divide by the day count for that same billing period. Enter actual inclusive dates or the contract’s manual day-count convention. Keep the daily rate unrounded until the final amount; taxes, fees and contractual rounding may change the actual bill.
How to Calculate a Prorated Bill?
The following example problems outline how to calculate Prorated Bill.
Example Problem #1:
- First, determine the monthly bill amount ($).
- The monthly bill amount ($) is given as 700.
- Next, determine the number of days used in the month.
- The number of days used in the month is provided as 10.
- Finally, calculate the Prorated Bill using the equation above:
PB = MB * Du / Dm (here Dm = 30 days)
The values given above are inserted into the equation below and the solution is calculated:
PB = 700 * 10 / 30 = 233.33 ($), rounded to cents
Example Problem #2:
For this problem, the variables needed are provided below:
monthly bill amount ($) = 800
number of days used in the month = 15; assume the same 30-day billing convention (the prorated amount is $400)
This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer.
PB = MB * Du / Dm (here Dm = 30 days) = ?
