by MarkEnhanced qPCR Efficiency CalculatorCalculate qPCR efficiency with a standard curve visualization. Standard Curve Slope ? Enter the slope from Ct vs. log(quantity), typically -3.1 to -3.6 (e.g., -3.32). Ct Value (optional) ? Enter a Ct value to estimate starting quantity (e.g., 20). Calculate ResetEnter the slope, then click “Calculate”. JavaScript is disabled. Please enable it to use the calculator.