Dilution Factor Calculator
The dilution factor from the volumes, and the concentration it produces — with the notation pinned down, since 1:10 means two different things.
Dilution factor is final volume ÷ initial volume.
How the dilution factor calculator works
Dilution factor is final volume ÷ initial volume. Adding 1 mL of stock to 9 mL of diluent gives 10 mL total and a factor of 10 — a "10-fold" or "1 in 10" dilution.
The ambiguity is "1:10". In most biology it means one part in ten parts total (factor 10); in some chemistry and medicine it means one part stock to ten parts diluent (factor 11). This calculator states which it is using, because getting it wrong is a tenfold error.
Formula: DF = V_final / V_stock; C_final = C_stock / DF
Worked examples
| Inputs | Dilution factor | Note |
|---|---|---|
| 1 mL into 9 mL | 10 | 10-fold |
| 1 mL into 10 mL | 11 | 11-fold — the "1:10" trap |
| Making 50 mL at 20-fold | 20 | 2.5 mL stock, 47.5 mL diluent |
FAQFrequently asked questions
What does 1:10 mean?
It depends on the field, which is the problem. In most biology it means 1 part in 10 total — a 10-fold dilution. In some chemistry it means 1 part stock to 10 parts diluent, which is 11-fold.
How do I make a 10-fold dilution?
1 part stock plus 9 parts diluent, giving 10 parts total.
What is the dilution factor?
Final volume divided by stock volume. The concentration falls by exactly that factor.
Do volumes add exactly?
Not always — mixing ethanol and water contracts noticeably. For dilute aqueous work the assumption is fine; for precize work, make up to a mark in a volumetric flask.
How do I avoid the ambiguity?
Write the fold change: "a 10-fold dilution" cannot be misread. Ratio notation always can.
Where these figures come from
- IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
- NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
- NIST Chemistry WebBook — thermochemical data
- National Institute of Standards and Technology — the US measurement and reference-data authority
Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.