Calculation methodology
The tools use geometry and proportional mixing math. They do not predict how a particular resin will cure.
Mold volume and batch totals
- Rectangle: inside length × inside width × depth.
- Circle: π × (inside diameter ÷ 2)² × depth.
- Known volume: your entered mixed volume per piece × its piece count, without calculating the geometry.
- Batch: sum of each cavity volume × its piece count.
- Total with extra: base volume × (1 + extra percentage ÷ 100).
Dimensions are stored internally in centimetres and volumes in millilitres. Changing the display units leaves those underlying values intact. Values remain unrounded for calculations; the result display rounds for readability. Metric amounts below a litre display in mL; larger amounts display in L. US amounts display in US fluid ounces or US liquid gallons. Very small positive amounts keep enough display digits to avoid appearing as zero. CSV dimensions remain in cm and volumes in mL, independent of the display units. CSV numbers keep up to 15 significant digits to avoid exposing floating-point calculation noise. Display and export precision do not establish the accuracy of your measurements.
Ratios always have a basis
Part A = total × A ÷ (A + B). Part B is the remaining total. The mold calculator splits liquid volume only. The separate ratio calculator splits a known volume or weight using the ratio for that same basis.
For example, 500 g at 4:1 by weight is 400 g Part A plus 100 g Part B. ResinBatch does not turn a volume ratio into a weight ratio.
Units
| Unit | Conversion used |
|---|---|
| 1 inch | 2.54 cm |
| 1 US fluid ounce | 29.5735295625 mL |
| 1 US liquid gallon | 3,785.411784 mL |
| 1 weight ounce | 28.349523125 g |
US liquid units are labelled explicitly. An ounce of weight and a fluid ounce are different measurements.
Kit quantities and material costs
Enter the combined mixed volume supplied by one kit and its price. Whole kits = batch volume ÷ kit volume, rounded up. Purchase cost counts those whole kits. Estimated material-used cost prorates the kit price to the volume used.
This assumes compatible kits with the product’s correct component proportions and no component shortage. It does not select a resin or verify package specifications. Costs exclude labor, packaging, sales fees, tax, shipping and other overhead; they are not net profit.
What the calculators do not model
The Known volume option accepts cavity-volume information you supply; it does not derive it from irregular dimensions. Detailed irregular geometry, displacement by objects, shrinkage, viscosity, pigment loading, staged pours, cure time, pot life and maximum safe batch size are outside the model. Extra allowance is your input, rather than a measured prediction of loss.
Checks and corrections
The project includes automated calculation cases for geometry, unit conversions, invalid inputs, ratio splits and kit rounding. Examples and exports use the same calculation functions. If a result looks wrong, compare the inputs, ratio basis and product instructions before mixing. You can report an issue through the project’s public feedback route once available.