Water Discount Calculator
Water takes no part in saponification: it carries the lye into the oils and then leaves again while the bar cures. Discounting it is therefore not about using less material but about making the lye solution stronger. Seventy-one grams of lye at 2 : 1 is 142 g of water, a 33% solution. Take 20% off and it is 113.6 g of water at 38.5%. A stronger solution puts less water in the batter, so trace arrives noticeably sooner — less time to swirl, but firm enough to unmould within a day, a shorter cure and less shrinkage. That is why discounts suit plain bars and rushed batches, while an intricate swirl wants the discount at zero or extra water instead.
Your numbers
Water
113.6g
Concentration
38.5%
Lye solution weight
184.6g
Formula
Water = Lye needed × Water : lye ratio × (1 − Water discount ÷ 100)
Around 50% is the practical ceiling: stronger than that and the lye will not all dissolve, leaving grains that end up in the bar. The bigger the discount the hotter the solution peaks, so start with cold water — and keep the order, lye into water, or it boils and spits. Goggles, gloves, and stainless or HDPE, never aluminium. Cutting the water never changes the lye weight. Scale the lye down with the water and you get a soft bar that will not set; weigh lye into the water field by mistake and you get a caustic one.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Lye needed (g)Lye needed; too little leaves it soft, too much leaves it caustic. | 71 | 0 and up |
| Water : lye ratio (×)Water per part lye; 2:1 is the common choice. | 2 | 0 ~ 4 |
| Water discount (%)How much you cut from the full water; the lye weight never changes. | 20 | 0 ~ 50 |
Step by step
Quick reference table
Results when only Lye needed (g) changes and everything else stays put.
| Lye needed (g) | Water (g) | Concentration (%) | Lye solution weight (g) |
|---|---|---|---|
| 35.5 | 56.8 | 38.5 | 92.3 |
| 53.3 | 85.3 | 38.5 | 138.6 |
| 71 | 113.6 | 38.5 | 184.6 |
| 107 | 171.2 | 38.5 | 278.2 |
| 142 | 227.2 | 38.5 | 369.2 |
What each result means
| Result | At default values |
|---|---|
| Water (g)Water to dissolve in; lye goes into water, never the reverse. | 113.6 |
| Concentration (%)How much of the whole is solute. | 38.5 |
| Lye solution weight (g)Water plus lye together — the total liquid you pour into the oils. | 184.6 |
Common mistakes
Around 50% is the practical ceiling: stronger than that and the lye will not all dissolve, leaving grains that end up in the bar. The bigger the discount the hotter the solution peaks, so start with cold water — and keep the order, lye into water, or it boils and spits. Goggles, gloves, and stainless or HDPE, never aluminium. Cutting the water never changes the lye weight. Scale the lye down with the water and you get a soft bar that will not set; weigh lye into the water field by mistake and you get a caustic one.
Glossary
- Lye needed
- Lye needed; too little leaves it soft, too much leaves it caustic.
- Water : lye ratio
- Water per part lye; 2:1 is the common choice.
- Water discount
- How much you cut from the full water; the lye weight never changes.
- Water
- Water to dissolve in; lye goes into water, never the reverse.
- Concentration
- How much of the whole is solute.
- Lye solution weight
- Water plus lye together — the total liquid you pour into the oils.
Frequently asked questions
Q. How is Water Discount Calculator calculated?
Water = Lye needed × Water : lye ratio × (1 − Water discount ÷ 100) — Water takes no part in saponification: it carries the lye into the oils and then leaves again while the bar cures. Discounting it is therefore not about using less material but about making the lye solution stronger. Seventy-one grams of lye at 2 : 1 is 142 g of water, a 33% solution. Take 20% off and it is 113.6 g of water at 38.5%. A stronger solution puts less water in the batter, so trace arrives noticeably sooner — less time to swirl, but firm enough to unmould within a day, a shorter cure and less shrinkage. That is why discounts suit plain bars and rushed batches, while an intricate swirl wants the discount at zero or extra water instead.
Q. Can you walk through an example?
With Lye needed 71g, Water : lye ratio 2×, Water discount 20%, the answer is Water 113.6g.
Q. What do I need to enter?
Enter Lye needed, Water : lye ratio, Water discount. 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 Lye needed (g) moves the answer to Lye needed (g) 35.5 → Water (g) 56.8 and Lye needed (g) 142 → Water (g) 227.2. 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?
Around 50% is the practical ceiling: stronger than that and the lye will not all dissolve, leaving grains that end up in the bar. The bigger the discount the hotter the solution peaks, so start with cold water — and keep the order, lye into water, or it boils and spits. Goggles, gloves, and stainless or HDPE, never aluminium. Cutting the water never changes the lye weight. Scale the lye down with the water and you get a soft bar that will not set; weigh lye into the water field by mistake and you get a caustic one.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.