Project notes
Understand this estimate
An epoxy mix ratio divides the two components by the parts stated by the product maker. Volume and weight are separate measurement bases and cannot be substituted for each other.
How to use the calculator
Read the product ratio
Enter the A and B parts exactly as printed, and select volume or weight only when the product gives a ratio on that basis.
Inputs Part A ratio · Part B ratio · Measurement basis
Choose what is already measured
For a total batch, the entered amount includes both components. For a known Part A amount, the tool calculates the matching Part B amount.
Inputs Known amount · Known amount
Formula and variables
For A:B = a:b and total T, Part A = T × a ÷ (a+b), Part B = T × b ÷ (a+b). If Part A is known, Part B = A × b ÷ a.
- a:bA-to-B ratio
- The component parts shown on the product instructions.parts
- TTotal batch
- The combined amount when total-batch mode is selected.US fl oz or g
What the result means
Result interpretation
Part A and Part B are split quantities; total mixed batch is their sum. The estimate does not verify the ratio for your product or replace its mixing instructions.
Limits and assumptions
Never substitute a volume ratio for a weight ratio. No brand-specific ratio is assumed. Adding extra hardener is not a way to change cure time.
Worked examples
Split a 32-fluid-ounce, 2:1 batch
Assumptions
- The label specifies 2:1 by volume.
- The requested total includes both components.
Calculation
- Part A = 32 × 2 ÷ 3 = 21.333 US fl oz.
- Part B = 32 × 1 ÷ 3 = 10.667 US fl oz.
| Part A | 21.33 US fl oz |
|---|---|
| Part B | 10.67 US fl oz |
| Total mixed batch | 32 US fl oz |
Add Part B to a measured Part A amount
Assumptions
- The product explicitly states 100:38 by weight.
- 60 g is the measured Part A mass.
Calculation
- Part B = 60 × 38 ÷ 100 = 22.8 g.
- Total = 60 + 22.8 = 82.8 g.
| Part A | 60 g |
|---|---|
| Part B | 22.8 g |
| Total mixed batch | 82.8 g |
Common questions
- Can I use a volume ratio when weighing the components?
- Only if the product also specifies that exact ratio by weight. Component densities differ.
- Can extra hardener make epoxy cure faster?
- Do not change the stated ratio to alter cure time. Follow the product instructions.