Fold Dilution Calculator
"Do a 5-fold dilution" just means divide the concentration by 5. Enter your start and target concentrations — the calculator finds the fold and the exact volumes.
Calculator
Fold Dilution Calculator
Was this calculator helpful?
Your feedback helps us improve the calculator and its explanations. This is CalculatorsPPM user feedback, not a Google review.
"Do a 5-fold dilution" just means divide the concentration by 5. Enter your start and target concentrations — the calculator finds the fold and the exact volumes.
How to use this calculator
- Enter starting concentration.
- Enter target concentration.
- Enter final volume.
- Get fold factor and stock volume.
The formula
Fold = C_start ÷ C_target; V_stock = V_final ÷ fold.
What the inputs mean
The target is the concentration you want, in PPM. The volume is how much liquid you are treating. The result tells you exactly how much product to add.
Worked example
2,000 PPM → 200 PPM in 50 mL: 10-fold; use 5 mL stock + 45 mL diluent.
Quick reference
| Fold | Example |
|---|---|
| 2-fold | 1 + 1 |
| 5-fold | 1 + 4 |
| 10-fold | 1 + 9 |
Parts stock + diluent.
Where you will actually use this
Protocols say "10-fold"; benches need milliliters.
- Assay prep
- Standard curves
- Microbiology
Mistakes that give wrong answers
- Calling a 1:10 dilution "10-fold" inconsistently (it is 10-fold — fine, but be consistent)
Key takeaways
- Formula: Fold = C1 ÷ C2; stock volume = V2 ÷ fold
- Remember: Parts stock + diluent.
- Watch out for: Calling a 1:10 dilution "10-fold" inconsistently (it is 10-fold — fine, but be consistent)
- Next step: run your own numbers in the calculator above, then verify with a measurement — calculated values are only as good as the inputs.
Frequently asked questions
What is a 10-fold dilution?
Concentration divided by 10 (e.g., 1 mL stock + 9 mL diluent).