Calculate specific growth rate, doubling time, daily growth rate, and fish growth coefficient from weights, time, or feeding data.
Specific Growth Rate Formula
The following formula is used to calculate the Specific Growth Rate.
- Where SGR is the Specific Growth Rate (%/day)
- WB is the weight at the beginning of the period (g)
- WE is the weight at the end of the period (g)
- t is the period length (days)
To calculate specific growth rate, subtract the natural logarithm of initial weight from the natural logarithm of final weight, divide by the period in days, then multiply by 100.
How to Calculate Specific Growth Rate?
The following two example problems outline the steps and information needed to calculate the Specific Growth Rate.
Example Problem #1
- First, determine the weight at the beginning of the period (g).
- The weight at the beginning of the period (g) is calculated to be 100.
- Next, determine the weight at the end of the period (g).
- The weight at the end of the period (g) is measured to be 150.
- Next, determine the period length (days).
- The period length (days) is found to be 3.
- Finally, calculate the Specific Growth Rate using the formula above:
SGR = (LN(WE) – LN (WB))*100 / (t)
The values provided above are inserted into the equation below and computed.
SGR = (LN(150) – LN (100))*100 / (3) = 13.52 (%/day)
Example Problem #2
The variables required for this problem are provided below:
weight at the beginning of the period (g) = 50
weight at the end of the period (g) = 400
period length (days) = 20
Test your knowledge using the equation and check your answer with the calculator.
SGR = (LN(WE) – LN (WB))*100 / (t) = (%/day)
