FAQ
Twelve questions that come up most often, from cleaners, brewers and lab users.
§ 1Questions
How do I read a 1:64 ratio?
1 part concentrate plus 64 parts water, totalling 65 parts. The concentrate is 1 ÷ 65 = 1.54 % of the bucket. For a 5 L bucket, that is 76.9 ml of concentrate plus 4 923.1 ml of water.
Why does my calculator output differ from the label by 1 to 2 ml?
Two reasons. First, labels often round (1:100 may print as 50 ml per 5 L instead of 49.5 ml). Second, some labels use the US convention of 1 part in X total rather than 1 part to X parts water. Check whether the label gives both numbers.
Is the calculator accurate for ABV blending?
It is accurate as a planning aid. For a bottled spirit, finish with a hydrometer reading at 20 °C; ethanol-water blends contract on mixing, so the volumetric prediction is approximate above 30 % v/v.
Which concentrate dilutions meet BS EN 1276?
Zoflora at 1:40 general dilution; Milton at the published bottle-sterilising ratio; Selgiene Ultra at 1:100; Dettol Trigene Advance at 1:100; Clinell Universal at 1:100; F10 SC at 1:500. Always re-verify against the live manufacturer page before bid response.
Can I use the chart on a phone without printing?
Yes. The chart pages are responsive. The print button strips browser chrome and ads when you need a paper copy for the supplies cupboard.
Does 1 % v/v equal 1:100?
Close but not exact. 1 % v/v = 1 ml in 100 ml total = 1:99 (1 part to 99 parts water). 1:100 is 1 part to 100 parts water = 0.99 % v/v.
How do I dilute 96 % IMS to 70 % ethanol for bench disinfection?
Pipette 729.2 ml of 96 % IMS into a 1 L volumetric flask. Top up to 1 L with distilled water. Mix. The result is approximately 70 % v/v.
Can I dilute concentrated sulphuric acid?
Yes, with the standard safety rule: water in the receiving vessel first, acid added second, slowly, with stirring. Wear splash goggles and gloves. See the always add acid to water page.
How long is a freshly diluted bleach solution active?
Approximately 24 hours at room temperature in a clean container. Sunlight and warmth shorten that. Mix fresh each shift.
How does serial dilution differ from a single-step dilution?
Serial dilution reaches very low concentrations through repeated 10× steps, each in a forgiving pipetting range. A single-step 1:1 000 000 dilution would require pipetting a microlitre of stock and is dominated by pipette error.
Why are units important in C₁V₁=C₂V₂?
The formula is mathematically unitless; both sides must match. Mixing M with mM on the same side gives an answer 1 000× off. Convert to common units before plugging in.
Does this site track my inputs?
No. The calculator runs in your browser. Inputs are not transmitted off device.
§ 2Related
Calculator · C₁V₁=C₂V₂ · Glossary · Sources