Take a recipe written for one batch size and restate it at another — candle, soap, bath bomb, perfume or resin. Enter the formula as printed or as percentages, say how big you want it, and every line comes back resized.
INPUTS
Type the formula in exactly as it is written. Every line is multiplied by one factor, so the ratios between them are untouched.
This changes nothing about the arithmetic. It changes what the tool tells you afterwards — every craft has one line that must not come out of a multiplication.
The formula you have
IngredientAmount
635 g total
The size you want
Scale it by
×
Halving is a factor below 1 — 0.5 for half a batch, 0.25 for a test pour.
A formula written as ratios scales cleanly in both directions. What it cannot tell you is whether the new batch still fits your equipment — check the pot, the mould and the pour before you mix.
RESULTS
SCALED
Everything moves by
2.00×
from 635 gto 1.27 kg
Weigh out
Ingredient
Was
Now
Base
500 g
1000 g
Second ingredient
120 g
240 g
Fragrance or colour
15.0 g
30.0 g
Every line moves by the same factor. That is correct for any formula written as a set of ratios.
How this is worked out
Scaling is one division and one multiplication. The batch you want, divided by the batch the formula makes, gives a factor; every line is multiplied by it. Because each line moves by the same amount, every ratio inside the formula is untouched — which is exactly what makes the result the same recipe rather than a new one. Entered as percentages the arithmetic is even shorter: each line is already a share, so it is resolved straight against the base amount you set. What the tool deliberately does not do is second-guess a line. It never recalculates a lye weight, never checks a fragrance ceiling and never looks at pour depth, because those are functions of what is in the formula rather than of how much of it there is — and each one belongs to the calculator that owns it.
factor = target batch ÷ source batch
new line = old line × factor
percentage = line ÷ base × 100
from a % = base amount × percentage ÷ 100
1 oz = 28.3495 g, so a mixed-unit formula converts before it totals
Questions makers ask
How do I scale a recipe to a different batch size?
Divide the batch you want by the batch the formula makes, then multiply every line by that factor. A formula that makes 12 items scaled to 30 is a factor of 2.50, so a 635 g batch becomes 1588 g and a 15 g fragrance line becomes 37.5 g.
Can I use this to halve a recipe?
Yes — a factor below 1 shrinks a batch by exactly the same arithmetic. The same formula at 0.5× comes to 318 g instead of 635 g. The practical limit is your scale rather than the maths: once a line drops under a gram or two, a scale that reads in whole grams is rounding away most of it.
Is it safe to scale every ingredient by the same amount?
For most lines, yes. Each of the five crafts on this site has one line that is the exception. The lye. It is worked out from which oils are in the blend, not from how much batter there is — scaling it alongside the oils happens to agree while the blend is untouched and stops agreeing the moment an oil is swapped. The pour depth, which is not a scaling question and is the one that matters. A bigger batch poured into the same mould is a deeper pour, and every system has a depth ceiling above which it overheats.
Why does the calculator ask what I am making?
Only to decide what to tell you afterwards. The arithmetic is identical for every craft — the craft choice changes the warning underneath the result and which of the dedicated calculators it points you at.
What is the difference between a percentage recipe and a weight recipe?
A weight recipe fits exactly one mould — the one it was written for. A percentage recipe fits any of them, because each line is a share of a base rather than a fixed amount. That is why nearly every published soap and perfume formula is written as percentages, and why converting yours is worth doing once.
My formula is in drops and parts. Will it still scale?
Drops and parts scale exactly like a weight does — they are ratios. What they cannot do is be added to one, so the totals are reported per kind of unit rather than as a single number. A formula written in drops. Drop size varies with the material and the pipette, so scaling drops multiplies that error rather than cancelling it — convert to grams once, then scale the grams.
Does doubling the batch double the time it takes?
Rarely, and that is the good news in scaling up. Melting, mixing and cleaning up barely move; only pouring and finishing scale with the count. If you are pricing the result, that is why cost per item falls with batch size even when material cost per item does not.