Converting Mass to Volume: A Guide for Handmade Sellers
Converting mass to volume is something every maker needs to understand: your suppliers sell ingredients by weight, but your recipes often call for volume. Here's how to make the conversion accurately, with real examples for soap, candle, and skincare makers.
As a maker, you run into this constantly: your supplier sells coconut oil by the kilogram, but your soap recipe calls for 500 mL. Or you buy shea butter by weight, but your formulation sheet lists everything in millilitres.
This is the mass-to-volume problem. It trips up a lot of handmade sellers, not because the maths is hard, but because nobody explains it clearly in a crafting context.
This guide does exactly that. You’ll find the formula, a density table for common crafting ingredients, and worked examples for soapmaking, candlemaking, and cosmetics.
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What is the difference between mass and volume?
Mass measures the amount of matter in a substance in grams or kilograms, while volume measures the space it occupies in millilitres or litres.
They sound similar, but they measure completely different things, and that difference matters every time you’re measuring out ingredients.
Mass is what your kitchen scale reads. If you put 100g of coconut oil on the scale, the display shows 100g regardless of how much space that oil takes up in your measuring cup.
Volume is what your measuring cup reads. If you pour liquid into a measuring jug to the 100 mL mark, you’re measuring how much space it occupies, not how heavy it is.
For water, 100g and 100 mL happen to be equivalent, which is why water is the reference point for the whole system. For everything else (oils, waxes, butters, alcohols), the relationship depends on density, and it varies by ingredient.
How do you convert mass to volume?
To convert mass to volume, divide the mass in grams by the ingredient’s density in g/mL to get the volume in millilitres.
The formula is:
Volume = Mass ÷ Density
Here’s a quick example. Coconut oil has a density of approximately 0.92 g/mL. If your recipe calls for 500g of coconut oil:
Volume = 500g ÷ 0.92 g/mL = 543.5 mL
So 500 grams of coconut oil occupies about 543.5 millilitres of space, meaningfully more than a 1:1 ratio would suggest. If you’d assumed 1g = 1 mL, you’d have measured out 500 mL instead, and your batch would be under by more than 40 mL.
That’s the kind of error that throws off both product consistency and your cost calculations.
How do I find the density of a crafting ingredient?
The best sources for crafting ingredient density are your supplier’s product data sheet, published ingredient databases, or our free grams-to-mL converter.
Three practical ways to find density:
Supplier data sheet: Most suppliers include density or specific gravity in the product specification. Specific gravity is numerically the same as density in g/mL for most crafting purposes.
Online databases: Ingredient databases like the ones maintained by cosmetic ingredient suppliers often list density values. For food-grade oils, the USDA FoodData Central is a reliable source.
Our free converter: The grams to mL converter has pre-loaded density values for common soap, candle, and cosmetic ingredients, so you can skip the lookup entirely.
If you’re working with an uncommon or custom-blended ingredient, you can measure density directly using a small graduated cylinder and a precision scale: fill the cylinder to a known volume (say 50 mL), weigh it empty and then full, and calculate density as mass ÷ volume.
Common crafting ingredient densities
These are approximate density values for ingredients frequently used in soap, candle, and skincare making. All values are in g/mL at room temperature (approximately 20°C / 68°F). For verified reference values, the NIST Chemistry WebBook provides density data for common compounds.
Oils and liquid fats
| Ingredient | Density (g/mL) | Notes |
|---|---|---|
| Water | 1.00 | Reference — 1g = 1 mL exactly |
| Coconut oil (liquid) | 0.92 | Solidifies below 24°C |
| Sweet almond oil | 0.91 | Stays liquid at room temp |
| Olive oil | 0.91 | Minor variation by grade |
| Castor oil | 0.96 | Higher density than most oils |
| Avocado oil | 0.91 | |
| Jojoba oil | 0.87 | Technically a liquid wax |
| Argan oil | 0.91 |
Butters and solid fats
| Ingredient | Density (g/mL) | Notes |
|---|---|---|
| Shea butter (melted) | 0.96 | Measure by weight when solid |
| Cocoa butter (melted) | 0.97 | |
| Mango butter (melted) | 0.91 | |
| Lard / tallow | 0.95 |
Waxes (melted)
| Ingredient | Density (g/mL) | Notes |
|---|---|---|
| Soy wax | 0.90 | Varies by blend |
| Beeswax | 0.96 | |
| Paraffin wax | 0.93 | Varies by grade |
| Coconut wax | 0.92 |
Other common ingredients
| Ingredient | Density (g/mL) | Notes |
|---|---|---|
| Isopropyl alcohol (91%) | 0.82 | |
| Glycerin | 1.26 | Denser than water |
| Witch hazel | 0.99 | |
| Aloe vera gel | ~1.00 | Varies by formulation |
| Lye (sodium hydroxide, dry) | — | Measure by weight only |
A note on temperature: Density changes with temperature. These values are for room-temperature liquids. If you’re working with melted waxes or butters, the liquid density listed above applies. Solid butters should be measured by weight, then melted. Don’t try to measure volume of a solid fat.
Mass-to-volume conversion examples by craft
Soapmaking
Cold-process and hot-process soap recipes are almost always written by weight (grams or ounces) because lye calculations depend on accurate mass measurements, which need to be recorded precisely in your soap batch record. Some older recipes and tutorials, however, give liquid oil amounts in cups or millilitres.
Example: A cold-process recipe calls for 450g of olive oil and 250g of coconut oil.
- Olive oil volume: 450 ÷ 0.91 = 495 mL
- Coconut oil volume: 250 ÷ 0.92 = 272 mL
If you’re scaling a batch or cross-referencing a volume-based recipe, these conversions tell you exactly what you’re working with.
Important for soapmaking: Lye (sodium hydroxide or potassium hydroxide) should always be measured by weight, not volume. The same applies to water: at 20°C, water is 1g/mL, but precision matters in soap chemistry and a scale measurement is more reliable than a measuring cup. For structuring your production records, see our guide to batch manufacturing records.
Candlemaking
Candle recipes are often specified by fragrance load percentage (percentage of fragrance oil relative to wax weight). If your fragrance oils are sold by the mL but you need to calculate cost by weight, the conversion works in reverse: Mass = Volume × Density.
Example: You have 100 mL of fragrance oil with a density of 1.05 g/mL.
Mass = 100 mL × 1.05 g/mL = 105g
For wax pouring, many makers work in volume when filling moulds or containers. If you know your container volume (say 300 mL) and you’re using soy wax (0.90 g/mL):
Mass needed = 300 mL × 0.90 g/mL = 270g of soy wax
This prevents over-ordering and helps you cost accurately per candle.
Cosmetics and skincare
Cosmetic formulations (serums, lotions, body butters) are typically written as percentages by weight, and precise measurement is a core requirement of good manufacturing practice (GMP). Converting to volume matters when you’re scaling up and need to work out how much space a batch will occupy, or when checking whether a recipe makes the advertised yield.
Example: A 100g face serum formula includes 5g of glycerin (density 1.26 g/mL):
Volume of glycerin = 5g ÷ 1.26 g/mL = 3.97 mL
If you assumed 1g = 1 mL, you’d measure 5 mL of glycerin, which actually contains 6.3g, not 5g. That’s a 26% error on a single ingredient, which could affect texture, viscosity, and cost.
Why accurate conversion matters for your cost of goods sold
Getting these conversions right isn’t just about recipe accuracy: it directly affects your cost of goods sold (COGS).
If you purchase ingredients by weight (which most wholesale suppliers sell by), your cost-per-gram is known. But if you measure by volume without converting, you can easily undercount how much of an ingredient each batch uses, which understates your material costs as a result. Accurate raw materials inventory management depends on this kind of precision at the ingredient level.
The practical impact: your pricing is based on incorrect COGS, so you may be selling products at a margin that’s lower than you think.
This is one of the reasons Craftybase lets you enter material quantities in any unit (grams, kilograms, mL, litres, or ounces) and handles unit conversion automatically when calculating the cost of each recipe. You enter your material purchase in the unit your supplier uses, set your recipe quantities in whatever unit you work in, and the software reconciles them behind the scenes.
Frequently Asked Questions
What is the formula for converting mass to volume?
The formula for converting mass to volume is: Volume = Mass ÷ Density. To use it, you need to know both the mass of your substance (in grams or kilograms) and its density (in g/mL or g/cm³). For example, 500g of coconut oil with a density of 0.92 g/mL gives a volume of 500 ÷ 0.92 = approximately 543 mL. One cubic centimetre equals one millilitre, so the result is directly in mL.
How do I convert grams to millilitres for soap and candle recipes?
To convert grams to millilitres for soap or candle ingredients, divide the mass in grams by the ingredient's density in g/mL. Water converts 1:1 (200g = 200 mL). Oils and waxes have lower densities: coconut oil is about 0.92 g/mL, so 200g of coconut oil equals approximately 217 mL. For common crafting ingredients, our free grams to mL converter handles the calculation with pre-loaded density values so you don't need to look them up.
Is 1 gram equal to 1 millilitre?
1 gram equals 1 millilitre only for water, because water has a density of exactly 1 g/mL at room temperature (20°C). For every other substance, the conversion depends on that substance's specific density. Oils, waxes, butters, and alcohols all have densities below 1 g/mL, meaning 1 gram of those materials takes up more than 1 mL of space. Glycerin, by contrast, is denser than water (1.26 g/mL), so 1 gram takes up less than 1 mL. Always check the density before assuming a 1:1 relationship.
Why does mass-to-volume conversion matter for recipe costing?
Mass-to-volume conversion matters for recipe costing because ingredients are usually purchased by weight but recipes may specify volume. If you don't convert accurately, your material cost calculations will be wrong; you may undercount ingredient usage per batch, which understates your cost of goods sold and leads to underpriced products. Craftybase lets you enter materials in any unit and handles the conversion automatically when calculating your COGS per recipe run.
How do I find the density of a crafting ingredient?
The best source for crafting ingredient density is your supplier's product data sheet, which typically lists density or specific gravity. For common ingredients: sweet almond oil is approximately 0.91 g/mL, shea butter (melted) is around 0.96 g/mL, and soy wax (melted) is approximately 0.90 g/mL. Our free grams to mL converter has pre-loaded density values for popular soap, candle, and cosmetic ingredients: look up the ingredient and it will convert for you.
How do I convert volume to mass for candle or soap making?
To convert volume to mass, reverse the formula: Mass = Volume × Density. For example, if you have 200 mL of soy wax (density 0.90 g/mL), the mass is 200 × 0.90 = 180g. This is useful for candle making when you know the volume of your mould or container and need to calculate how much wax to weigh out: multiply the container volume in mL by the wax density to get the mass needed in grams.
Converting mass to volume comes down to one thing: density. Once you know the density of your ingredient, the formula is straightforward: divide mass by density to get volume, or multiply volume by density to get mass.
For handmade sellers, getting this right matters beyond just making accurate batches. Every gram you miscount is a discrepancy in your COGS, which flows through to your pricing. The practical fix is to either keep a density reference sheet for your most-used ingredients (the tables above are a good starting point) or use a tool that handles the conversion for you.
If you’re regularly converting between grams and millilitres for soap, candle, or cosmetic ingredients, try the free grams to mL converter: it has pre-loaded density values for the most common crafting ingredients and does the calculation instantly.
