How It Works
This calculator works in 4 steps.
Enter the measured concentration
Type the ng/µL value.
Enter the target
Type the RNA mass per reaction, such as 1,000 ng, or a target ng/µL.
Enter the final volume
Type the reaction or tube volume.
Read the volumes
The calculator returns RNA and nuclease-free water volumes and flags volumes that exceed the reaction's template limit.
The Formula
The formula divides the target RNA mass by the measured concentration.
V_RNA = m / C₁RNA (ng/µL) = A260 × 40 × DFV_water = V₂ − V_RNA- m:
- Target RNA mass (ng)
- C₁:
- Measured RNA concentration (ng/µL)
- V₂:
- Final volume (µL)
For 1,000 ng RNA in 20 µL from an 800 ng/µL sample, add 1.25 µL RNA and 18.75 µL nuclease-free water.
Conversion Table
The conversion table gives RNA and water volumes for 6 mass targets.
| Stock | Target mass | Final volume | RNA volume | Water |
|---|---|---|---|---|
| 800 ng/µL | 1,000 ng | 20 µL | 1.25 µL | 18.75 µL |
| 250 ng/µL | 500 ng | 10 µL | 2 µL | 8 µL |
| 1,500 ng/µL | 2,000 ng | 15 µL | 1.333 µL | 13.67 µL |
| 120 ng/µL | 100 ng | 10 µL | 0.8333 µL | 9.167 µL |
| 60 ng/µL | 200 ng | 20 µL | 3.333 µL | 16.67 µL |
| 2,000 ng/µL | 1,000 ng | 50 µL | 0.5 µL | 49.5 µL |
What Is the RNA Dilution Calculator?
The RNA Dilution Calculator is a tool that returns the RNA volume and nuclease-free water volume needed for a set RNA mass or concentration, such as 1 µg in 20 µL for reverse transcription. The calculator works in ng/µL and ng.
An A260 of 1.0 equals about 40 ng/µL of RNA. Pure RNA has an A260/A280 ratio near 2.0. RNA degrades in contact with ribonucleases (RNases), so the diluent must be nuclease-free water or RNase-free buffer, and the calculator prints that requirement with each result.
Common Uses
There are 5 main uses of this calculator.
cDNA synthesis
Users load equal RNA mass into reverse transcription reactions.
RNA-seq library input
Sequencing labs set RNA to the kit input range.
Northern blots
Researchers load equal RNA mass per lane.
In vitro translation
Users add a set mRNA mass to lysate reactions.
RT-qPCR
Labs normalize RNA input across samples.