Calculate amplification efficiency from the slope of a qPCR standard curve.
| Efficiency E | – |
| Efficiency (%) | – |
| Amplification (1+E) | – |
Use this calculator as a run-quality check. One hundred percent means the product doubles every cycle. Take the slope from a plot of cycle threshold (Ct) versus log₁₀ of the dilution, copy number, or other known quantity.
Efficiency E is 10^(−1/slope) − 1. Percent is E × 100. Amplification is 1 + E (2.0 at 100%). A ten-fold dilution series with ideal doubling has a slope of about −3.32. The slope must be negative; a positive or zero slope is not a valid standard curve.
Typical acceptable efficiency is often quoted near 90–110%, but the acceptable window depends on your assay, chemistry, and laboratory SOP. This calculator does not judge pass or fail; it only converts the slope.
Standard-curve slope: The slope of Ct versus log₁₀(quantity). A 1:10 dilution series often gives about −3.3 when efficiency is close to 100%.
Efficiency E: Fractional efficiency (1.0 = 100%, 0.9 = 90%).
Efficiency (%): The same value as a percentage.
Amplification (1+E): Fold increase per cycle.
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