# PCR Cycle Number / Product Amount Calculator (2^n)

PCR product from ideal exponential amplification copies = template × (1 + e)^n (2^n at 100%), with ng conversion from amplicon length, plateau flag (~10¹²–10¹³ molecules), and >35-cycle warning. Derived from Saiki 1988, Innis & Gelfand 1990, Lorenz 2012. Lab-planning use only.

> Canonical page: https://elysiatools.com/en/tools/pcr-cycle-number

- **Category:** Education

- **Keywords:** pcr cycle number, pcr product amount, 2^n amplification, pcr efficiency, pcr yield calculator, exponential amplification, pcr plateau, template copies, amplicon mass, pcr mathematics, pcr, molecular biology

## Overview

The PCR Cycle Number / Product Amount Calculator estimates amplified DNA copies from starting template copies, cycle number, and per-cycle efficiency. It can also convert the result to nanograms when you enter an amplicon length, while flagging results near the expected plateau range and cycles above 35 for lab-planning context.

## Inputs

- **Template Copies** (number): Starting number of target molecules (see the companion copy-number tool).
- **Cycle Number** (number): Number of thermal cycles (most protocols: 25–35).
- **Efficiency (%/cycle)** (number): Per-cycle amplification efficiency; 100% = perfect doubling, real PCR typically 70–100%.
- **Amplicon Length (bp, optional)** (number): Amplicon length in base pairs for the ng-yield conversion; enter 0 to skip.
- **Decimal Places** (number)

## When to use

- Estimate PCR product copies from a known starting number of template molecules.
- Compare ideal 100% efficiency with a more realistic PCR efficiency.
- Convert estimated amplicon copies to mass in nanograms using the amplicon length.

## How it works

- Enter the starting template copies and number of thermal cycles.
- Set the per-cycle amplification efficiency; 100% efficiency represents doubling each cycle.
- Optionally enter the amplicon length in base pairs to calculate an estimated mass in nanograms.
- The calculator returns ideal and effective amplification values, product copies, optional mass, and a plateau or high-cycle indication when applicable.

## Use cases

- Compare expected product yield at different cycle numbers or PCR efficiencies.
- Estimate whether a planned reaction may approach the 10^12–10^13 molecule plateau range.
- Approximate the mass of a PCR product when its length is known.

## Frequently asked questions

### What formula does the calculator use?

It uses template copies × (1 + efficiency)^n, where efficiency is expressed per cycle and n is the cycle number.

### What does 100% PCR efficiency mean?

A 100% efficiency means the target product doubles during every cycle, giving the familiar 2^n amplification.

### Is amplicon length required?

No. Enter 0 or leave the optional length at 0 to skip the nanogram conversion.

### How is product mass calculated?

The calculator uses the estimated product copies, amplicon length, an approximate molecular weight of 660 Da per base pair, and Avogadro's constant.

### Does this predict the exact PCR yield?

No. It is an idealized planning estimate; reagent limits and the PCR plateau can make actual yields lower.

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