Calculadora de Eficiência de qPCR
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
E = 10^(−1/slope) − 1; eficiência% = E × 100
About this calculator
The qPCR Efficiency Calculator is a tool that determines the efficiency of a quantitative real-time PCR (qPCR) reaction. Efficiency is calculated from the slope of the standard curve generated by serial dilutions of a sample. The formula used is E = 10^(-1/slope) - 1, where E is efficiency in decimal. The result is also presented as a percentage by multiplying E by 100. Ideal efficiency ranges from 90% to 110%, corresponding to a slope near -3.32.
How it works: the user enters the slope value obtained from the standard curve of the experiment. The calculator applies the formula and returns the decimal and percent efficiency. It also indicates whether the efficiency is within the acceptable range. This allows quick assessment of qPCR reaction quality without manual calculations.
When to use: this calculator is essential for researchers and lab technicians performing qPCR for DNA or RNA quantification. It is used after obtaining the standard curve to verify if the reaction is optimized. Proper efficiency ensures accurate and reliable quantification results, especially in gene expression studies or molecular diagnostics.
Common precautions: the slope should come from a standard curve with at least 5 dilution points, in triplicate, and with R² > 0.99. Efficiency values outside 90-110% indicate issues such as reaction inhibitors, pipetting errors, or inefficient primers. Do not confuse slope with efficiency: steeper slopes (more negative) result in lower efficiencies.
Frequently asked questions
What does a qPCR efficiency below 90% mean?
It indicates the reaction is not amplifying efficiently, possibly due to inhibitors, poorly designed primers, or inadequate reaction conditions.
Can I use the calculator if my slope is positive?
No, positive slopes are not expected in qPCR and indicate experimental error. The calculator will return an invalid efficiency.
How important is the R² of the standard curve?
R² measures linearity. An R² above 0.99 is recommended to ensure reliable data and accurate efficiency calculation.
Does the calculator work for probe-based qPCR or SYBR Green?
Yes, the formula is the same regardless of detection method, as long as the standard curve is properly generated.
What should I do if efficiency is above 110%?
It may indicate contamination, primer dimers, or pipetting errors. Check the curve and repeat the experiment.