Lotion Calculator
Build a lotion recipe by weight: set your batch size and the oil, emulsifier, preservative and additive percentages, and the water phase fills the rest. Every amount is worked out in your browser.
Recipe by weight
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Your percentages add up to more than 100%, reduce them.
Show the math
Each phase is a percentage of the batch, and the water phase makes up whatever is left:
grams = batch × percent ÷ 100 · water % = 100 − (oil + emulsifier + preservative + additives)
Any lotion containing water will grow mould and bacteria without a proper broad-spectrum preservative, this is a safety must, not optional. Follow your emulsifier's recommended usage rate and your preservative's, and make in clean, sanitised equipment.
What this does
A lotion calculator builds a recipe by weight: set your batch size and the oil, emulsifier, preservative, and additive percentages, and the water phase fills the rest.
How to use it
- Enter the batch weight.
- Set each phase percentage.
- Let the water phase fill to 100%.
- Read every ingredient in grams.
How it works
The water phase makes up whatever is left to reach 100%. Any lotion with water needs a broad-spectrum preservative — this is a safety must, not optional.
grams = batch × percent ÷ 100
Understanding your result
The water phase fills whatever the oils, emulsifier, and additives leave, and any lotion containing water absolutely needs a broad-spectrum preservative, this is a safety requirement, not an optional extra, because water grows mould and bacteria you cannot see. Keep the emulsifier within its recommended range so the cream holds together, and sanitise every tool.
Example
A 200 g batch at 20% oil uses 40 g of oils.
Sources & methodology
Last updated .
Frequently asked questions
How are the amounts found?
Each phase is a percentage of the batch weight (grams = batch \u00d7 percent \u00f7 100), and the water phase makes up whatever is left to reach 100%.
Why is a preservative essential?
Any lotion that contains water will grow mould and bacteria without a broad-spectrum preservative. This is a safety must, not optional \u2014 follow your preservative\u2019s rated usage rate.
How much emulsifier do I need?
It depends on your emulsifier and oil load \u2014 follow the supplier\u2019s recommended rate. Too little and the emulsion splits.
Do you store anything?
No \u2014 every calculation runs locally in your browser.
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