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Blend Two Strengths to a Target

Where the target sits between the strong and weak stock sets the ratio. Divide the target’s distance from the weak stock by the gap between the two, and that is the share of the strong one.

Your numbers

Amount of A

280mL

Amount of B

720mL

Concentration

12%

What it means

The target lies between the two stocks, so this mix works.

Formula

Amount of A = Volume (mL) × (Target % − B share) ÷ (A share − B share)

If the target is not between the two, no mix reaches it. You cannot make 35% out of 30% and 5% — you need a stronger stock.

What to enter

InputDefaultAccepted range
Volume (mL) (mL)Volume in millilitres.1,0000 and up
A share (%)The percentage that applies to the first item.300 ~ 100
B share (%)The percentage that applies to the second item.50 ~ 100
Target % (%)The concentration you want; lower means add water, higher means add solute.120 ~ 100

Step by step

FormulaAmount of A = Volume (mL) × (Target % − B share) ÷ (A share − B share)
With the default numbersAmount of A = 1,000 × (12 − 5) ÷ (30 − 5)
AnswerAmount of A = 280 mL

Quick reference table

Results when only Volume (mL) (mL) changes and everything else stays put.

Volume (mL) (mL)Amount of A (mL)Amount of B (mL)Concentration (%)
50014036012
75021054012
1,00028072012
1,5004201,08012
2,0005601,44012

What each result means

ResultAt default values
Amount of A (mL)How much of the stronger liquid to use.280
Amount of B (mL)How much of the weaker liquid to use.720
Concentration (%)How much of the whole is solute.12

Common mistakes

If the target is not between the two, no mix reaches it. You cannot make 35% out of 30% and 5% — you need a stronger stock.

Glossary

Volume (mL)
Volume in millilitres.
A share
The percentage that applies to the first item.
B share
The percentage that applies to the second item.
Target %
The concentration you want; lower means add water, higher means add solute.
Amount of A
How much of the stronger liquid to use.
Amount of B
How much of the weaker liquid to use.
Concentration
How much of the whole is solute.

Frequently asked questions

Q. How is Blend Two Strengths to a Target calculated?

Amount of A = Volume (mL) × (Target % − B share) ÷ (A share − B share) — Where the target sits between the strong and weak stock sets the ratio. Divide the target’s distance from the weak stock by the gap between the two, and that is the share of the strong one.

Q. Can you walk through an example?

With Volume (mL) 1,000mL, A share 30%, B share 5%, Target % 12%, the answer is Amount of A 280mL.

Q. What do I need to enter?

Enter Volume (mL), A share, B share, Target %. The result recalculates as you type, and an empty box counts as zero.

Q. How much does the answer move if I change a number?

Changing only Volume (mL) (mL) moves the answer to Volume (mL) (mL) 500 → Amount of A (mL) 140 and Volume (mL) (mL) 2,000 → Amount of A (mL) 560. The table below lays out five steps.

Q. How are the numbers rounded?

Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.

Q. Anything to watch out for?

If the target is not between the two, no mix reaches it. You cannot make 35% out of 30% and 5% — you need a stronger stock.

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