Part A and Part B ratio searches are high-trust queries. This guide explains why volume and weight ratios can differ and why users must follow the product's own instructions.
Direct Answer
Use the basis stated on the product: graduated measures for a volume ratio, a scale for a weight ratio. The numbers are not generally interchangeable because the two components can have different densities. Never derive a substitute weight ratio without the manufacturer's approved ratio or component data.
Takeaways
Part A and Part B may have different densities, so the same volume can weigh different amounts. That is why a product can specify one ratio by volume and another by weight.
This guide explains planning logic. The exact ratio must come from the product documentation for the resin being used.
Consider a hypothetical product requiring 200 ml of Part A and 100 ml of Part B. If its component densities were 1.10 and 1.00 g/ml, the weights would be 220 g and 100 g: a 2.2:1 weight ratio. This example demonstrates the arithmetic only; the densities and ratio must not be used for another product. Actual data must come from its manufacturer.
| Component | Example volume | Assumed density | Calculated weight |
|---|---|---|---|
| A | 200 ml | 1.10 g/ml | 220 g |
| B | 100 ml | 1.00 g/ml | 100 g |
| Ratio | 2:1 | Different densities | 2.2:1 |
Hypothetical component properties for explanation, not a resin formulation or mixing recommendation.
If your actual label specifies 100:45 by weight, a 290 g total batch is 290 × 100 / 145 = 200 g of A and 90 g of B. Tare the container and follow the product's measurement and mixing instructions. Do not pour 200 ml plus 90 ml merely because the scale example uses those numbers. The same total volume is split differently unless the label confirms the corresponding volume ratio.
The quantity result is total mixed resin. An A/B split is shown only after you enter a product's volume ratio; the tool does not infer that ratio from a resin class. Weight ratios require the product's weight quantities or component data. Choosing a different ratio does not change the cavity's geometric volume. If a kit is described only by component weight, check the manufacturer's stated yield rather than assuming kilograms equal liters.
A ratio is not a loss allowance: changing the reserve changes how much matched resin/hardener you buy, while the product chemistry still determines their ratio. The tool supports a user-confirmed volume ratio or directs you back to the manufacturer's weight quantities. It never substitutes a universal density to infer the component masses. For Part A and Part B amounts at 1:1, 2:1 and 3:1, use the resin to hardener ratio chart.
FAQ
No. Some products specify ratio by volume, some by weight, and some provide both. Follow the product instructions.
Only if you know the density of both parts. Otherwise use the ratio supplied by the manufacturer.
The epoxy may stay soft, sticky, brittle, cloudy, or fail to cure properly.
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Reviewed · Calculation notes and corrections