qPCR Efficiency Calculator
FREE TOOL
Enter at least 3 data points from your standard curve. Use log₁₀ of the template concentration (e.g. log of copy number or dilution factor).
--
% EFFICIENCY
--
SLOPE
--
R² VALUE
📊 Standard Curve Data Points
How to Use the qPCR Efficiency Calculator
Step 1: Enter your standard curve data. For each dilution enter the log₁₀ of the concentration (e.g. if you used 10⁶ copies enter 6) and the corresponding average Ct value.
Step 2: Use at least 3 data points for a valid result. 5 points across a 5-log range is the recommended standard.
Step 3: Click Calculate. The tool performs linear regression to find the slope and R² of your standard curve, then calculates efficiency from the slope.
qPCR Efficiency Formula
// Efficiency from slope:
E = (10^(-1/slope) - 1) × 100%
// Ideal values:
Efficiency = 90–110% (ideal: 100%)
Slope = −3.1 to −3.6 (ideal: −3.32)
R² = ≥ 0.99 (ideal: 1.0)
// At 100% efficiency each cycle doubles DNA:
E = 100% → slope = −3.322
E = (10^(-1/slope) - 1) × 100%
// Ideal values:
Efficiency = 90–110% (ideal: 100%)
Slope = −3.1 to −3.6 (ideal: −3.32)
R² = ≥ 0.99 (ideal: 1.0)
// At 100% efficiency each cycle doubles DNA:
E = 100% → slope = −3.322
Troubleshooting Poor Efficiency
If efficiency is below 90% check for PCR inhibitors in your sample, suboptimal primer design or problems with the standard curve dilutions. If efficiency is above 110% check for pipetting errors or primer dimers in your no-template control.