Calculator inputs
Use the responsive field grid below. It shows three columns on large screens, two on smaller screens, and one on mobile.
Example data table
| Sample | RNA amount | Cells | Viability | Recovery | Purity | Length | RNA per cell | Copies per cell |
|---|---|---|---|---|---|---|---|---|
| Culture A | 500 ng | 200,000 | 90% | 80% | 95% | 1,800 nt | 3.2986 pg | 3.2459e+6 |
| Culture B | 1.2 µg | 800,000 | 95% | 85% | 92% | 2,200 nt | 3.4180 pg | 2.7518e+6 |
| Primary Cells | 75 ng | 50,000 | 80% | 70% | 88% | 1,200 nt | 3.5357 pg | 5.2188e+6 |
Formula used
Effective live cells = Entered cells × (Viability ÷ 100)
Adjusted usable RNA = Measured RNA × Dilution factor × (Purity ÷ 100) ÷ (Recovery efficiency ÷ 100)
RNA per cell = Adjusted usable RNA mass ÷ Effective live cells
Molecular weight ≈ Transcript length × Average nucleotide mass
Moles = Adjusted usable RNA mass ÷ Molecular weight
Copies = Moles × Avogadro constant
Copies per cell = Total copies ÷ Effective live cells
Copy estimates assume a single RNA species with the entered transcript length. Mixed RNA populations need transcript-specific quantification or sequencing-based normalization.
How to use this calculator
- Enter the measured RNA mass from your extraction or assay.
- Select the correct mass unit so the calculator converts values accurately.
- Provide the number of cells represented by that RNA sample.
- Adjust viability to focus on live-cell RNA content instead of total counted cells.
- Enter recovery efficiency if extraction losses should be corrected upward.
- Enter usable RNA purity when contamination lowers the informative RNA fraction.
- Use dilution factor to scale concentrations back to the original sample.
- Add transcript length to estimate copies per cell for one RNA species.
- Press the calculate button to show results above the form.
- Export the displayed results to CSV or PDF for records.
Frequently asked questions
1. What does RNA per cell tell me?
It estimates how much RNA is associated with each effective cell after adjusting for live-cell fraction, extraction recovery, dilution, and usable purity assumptions.
2. Why is viability included?
Viability lets you normalize RNA to live cells instead of all counted cells. That can improve interpretation when dead cells or debris affect total counts.
3. Why does recovery efficiency increase adjusted RNA?
If recovery is below 100%, the measured mass likely underestimates original RNA. Dividing by recovery fraction approximates the pre-loss amount.
4. What purity factor should I use?
Use purity to represent the fraction of measured mass that is informative RNA. Lower values help correct for contaminants or non-target material.
5. Are copy estimates exact?
No. They are approximations based on one transcript length and an average nucleotide mass. Transcript composition, modifications, and heterogeneity can shift true values.
6. Can I use this for total RNA and mRNA?
Yes. The mass-based outputs work for any RNA pool. Copy estimates are most meaningful for a defined transcript or a narrow molecular class.
7. Which output is best for comparing experiments?
RNA per cell in pg or ng per million cells is usually easiest for comparing cultures, treatments, harvests, or extraction runs across batches.
8. Should I use the default 340 Da value?
It is a practical average for many RNA calculations. Change it if your protocol uses a more specific molecular weight assumption.