Enter the monthly bill amount ($) and the number of days used in the month into the Prorated Bill Calculator. The calculator will evaluate and display the Prorated Bill. 

Prorate Bill Calculator

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Fill in Total Days in Month and any 2 of the other fields to calculate the third.


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Prorated Bill Formula

The following formula is used to calculate the Prorated Bill. 

PB = MB * D_u/D_m

Formula source:  Social Security Administration – Proration of SSI Payments (Handbook §2184.4)

  • Where PB is the Prorated Bill ($)
  • MB is the monthly bill amount ($) 
  • D_u is the number of days used in the month 
  • D_m is the number of days in the month

To calculate a prorated bill, multiply the monthly bill by the number of days used in the month, then divide by the number of days in the month.

How to Calculate a Prorated Bill?

The following example problems outline how to calculate Prorated Bill.

Example Problem #1:

  1. First, determine the monthly bill amount ($).
    • The monthly bill amount ($) is given as: 700.
  2. Next, determine the number of days used in the month.
    • The number of days used in the month is provided as: 10.
  3. Finally, calculate the Prorated Bill using the equation above: 

PB = MB / 30.5 * #D

The values given above are inserted into the equation below and the solution is calculated:

PB = 700 / 30.5 * 10 = 229.508 ($)


Example Problem #2: 

For this problem, the variables needed are provided below:

monthly bill amount ($) = 800

number of days used in the month = 15

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

PB = MB / 30.5 * #D = ?