Water Needed to Dilute
Diluting does not change the amount of solute, so the final mass grows by the ratio of the starting concentration to the target.
Your numbers
Water to add
900g
Solution (g)
1,200g
Formula
Water to add = Solution (g) × (Concentration ÷ Target % − 1)
Taking 300 g of 20% down to 5% needs 900 g more water for 1,200 g total — quartering the strength quadruples the volume.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Concentration (%)How much of the whole is solute. | 20 | 0.01 ~ 100 |
| Solution (g) (g)Solute and solvent together. | 300 | 0 and up |
| Target % (%)The concentration you want; lower means add water, higher means add solute. | 5 | 0.01 ~ 100 |
Step by step
Quick reference table
Results when only Concentration (%) changes and everything else stays put.
| Concentration (%) | Water to add (g) | Solution (g) (g) |
|---|---|---|
| 10 | 300 | 600 |
| 15 | 600 | 900 |
| 20 | 900 | 1,200 |
| 30 | 1,500 | 1,800 |
| 40 | 2,100 | 2,400 |
What each result means
| Result | At default values |
|---|---|
| Water to add (g)Extra water needed to reach the target. | 900 |
| Solution (g) (g)Solute and solvent together. | 1,200 |
Common mistakes
Taking 300 g of 20% down to 5% needs 900 g more water for 1,200 g total — quartering the strength quadruples the volume.
Glossary
- Concentration
- How much of the whole is solute.
- Solution (g)
- Solute and solvent together.
- Target %
- The concentration you want; lower means add water, higher means add solute.
- Water to add
- Extra water needed to reach the target.
Frequently asked questions
Q. How is Water Needed to Dilute calculated?
Water to add = Solution (g) × (Concentration ÷ Target % − 1) — Diluting does not change the amount of solute, so the final mass grows by the ratio of the starting concentration to the target.
Q. Can you walk through an example?
With Concentration 20%, Solution (g) 300g, Target % 5%, the answer is Water to add 900g.
Q. What do I need to enter?
Enter Concentration, Solution (g), 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 Concentration (%) moves the answer to Concentration (%) 10 → Water to add (g) 300 and Concentration (%) 40 → Water to add (g) 2,100. 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?
Taking 300 g of 20% down to 5% needs 900 g more water for 1,200 g total — quartering the strength quadruples the volume.
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