Solve a part amount, base amount, or percentage rate using P = (R / 100) × B. Choose Compare two rates (PBR) for a unitless rate comparison.

Part Base Rate Formula

The examples below use Compare two rates (PBR). For part/base/percentage problems, use P = (R / 100) × B, B = P / (R / 100), or R = (P / B) × 100.

PBR = P / R
  • Where PBR is the Part Base Rate (a unitless multiplier or ratio)
  • P is the part percentage (or part rate), expressed as a percent (%) or decimal fraction
  • R is the base (reference) rate, expressed in the same form as P (percent or fraction)

To calculate the part base rate, divide the part percentage/rate (P) by the base rate (R). If you use percentages, the percent units cancel in the division; if you use fractions, divide the fractions.

How to Calculate Part Base Rate?

The following example problems outline how to calculate Part Base Rate.

Example Problem #1:

  1. First, determine the part percentage (P).
    • The part percentage (P) is given as: 50%.
  2. Next, determine the base rate (R).
    • The base rate (R) is provided as: 2%.
  3. Finally, calculate the Part Base Rate using the equation above: 

PBR = P / R

The values provided above are inserted into the equation below and computed.

PBR = 50% / 2% = 25

Example Problem #2: 

For this problem, the variables required are provided below:

part percentage (P) = 60%

base rate (R) = 3%

Test your knowledge using the equation and check your answer with the calculator.

PBR = P / R = 60% / 3% = 20