THE METHOD, MADE CLEAR
From usable volume
to fill-material mass.
Pourmass estimates one material batch for a number of equal candle vessels. It multiplies usable volume by the density you supply, then adds an optional percentage reserve.
What “fill material” means
The output is the mass of the material described by the density you enter. If your density describes a finished mixture, the mass refers to that whole mixture. If it describes a single material, the mass refers to that material under the stated volume assumption. The calculator does not split a mixture into wax, fragrance, colour or other ingredients.
This is not a candle formulation calculator. No additive percentages, processing temperatures, wick selection, burn performance or container suitability are inferred from the result. Those are different questions from the volume-to-mass arithmetic here.
Use the volume you intend to fill
The useful volume is the space up to your chosen fill level, after accounting for anything that occupies that space. It is not automatically the vessel’s capacity to its rim. The calculator provides no recommended headspace or fill height. Enter an appropriate usable volume for the actual vessel and plan.
If you already know the usable volume, enter it in millilitres or litres. One litre is exactly 1,000 millilitres. Switching between these units converts the value so the physical volume remains the same. An amount entered as 200 mL becomes 0.2 L.
Calculating volume from straight geometry
A straight cylindrical interior uses its inside diameter and usable fill height. A straight rectangular interior uses its inside length, inside width and usable fill height. The tool converts those lengths to centimetres before calculating volume. One cubic centimetre equals one millilitre.
Cylinder volume (mL) = π × inside diameter² ÷ 4 × fill height, with lengths in cm
Rectangle volume (mL) = inside length × inside width × fill height, with lengths in cm
Use inside measurements, rather than the outside of a thick-walled vessel. These formulas assume straight walls and a flat, matching base. A tapered, curved, rounded or otherwise irregular interior needs a suitable known usable volume instead. No displacement is automatically deducted for components inside the vessel.
Worked example: a cylindrical interior
An inside diameter of 7.5 cm and a usable fill height of 8 cm give π × 7.5² ÷ 4 × 8 ≈ 353.429 mL. With an illustrative entered density of 0.9 g/mL, the fill material per vessel is approximately 318.086 g.
The 0.9 value is part of this arithmetic example. It is not a density assigned to your own wax or mixture.
Density is the essential input
Density in g/mL means how many grams correspond to one millilitre of the material under the relevant conditions. A material with a density of 0.9 g/mL has 180 g in a 200 mL volume in this model. The tool always takes density as an explicit input; selecting a candle style or vessel shape does not supply one.
Use your own measured value or appropriate data for the actual material and intended fill condition. The calculator does not determine the density, translate a product name into density, or model changes with processing conditions. If the density input is wrong for the material, the mass estimate will inherit that error.
Mass per vessel (g) = usable volume per vessel (mL) × density (g/mL)
Required fill mass = mass per vessel × number of equal vessels
Scaling a batch and adding reserve
Vessel count must be a whole number from one to 10,000. All counted vessels share the same entered usable volume. For different vessel sizes, make separate plans and combine the mass figures yourself.
Reserve is an extra amount expressed as a percentage of the required fill mass. A 10% reserve adds one tenth of the required mass. That extra material is not added to the usable volume of each vessel; it is an allowance in the batch total.
Reserve mass = required fill mass × reserve percentage ÷ 100
Total batch mass = required fill mass + reserve mass
Worked example: six 200 mL fills
At an illustrative density of 0.9 g/mL, each 200 mL fill needs 180 g. Six equal fills need 1,080 g. A 10% reserve adds 108 g, making the batch estimate 1,188 g. With a 0% reserve, it remains 1,080 g.
The six vessels contain a total usable fill volume of 1,200 mL, or 1.2 L, regardless of the reserve. Reserve is spare material in this calculation.
An extra percentage is not a loss fraction
Adding 10% of a required amount differs from compensating for losing 10% of the starting amount. If 90% of a starting amount remains, recovering a particular final amount would require division by 0.9. Pourmass does not use that loss-fraction formula: its reserve field explicitly adds a percentage of required mass. Choose a reserve figure that reflects the planning meaning you intend, rather than assuming the two percentages are interchangeable.
Grams and ounces
The default mass display is grams. The optional ounce display uses the mass ounce, exactly 28.349523125 g. It does not mean a fluid ounce, and no regional fluid-ounce volume is selected. Changing mass display converts the result while keeping the same volume, density and physical mass.
Saving and checking a result
Copy summary records the usable volume, supplied density, vessel count, reserve and displayed mass. CSV records the underlying volumes in mL and masses in grams for one consistent stored unit system. Screen numbers are rounded for readability; calculations and exports retain more precision.
The tool rejects empty values, non-positive volume or density, fractional vessel counts, and unsupported numerical ranges. Clearing an input clears the previous estimate and disables exports until a valid plan is restored. Calculations happen in your browser and are not sent to the site operator.