Calculator Inputs
Formula Used
Adjusted Total = Target Total × (1 + Waste % / 100)
Fiberglass = Adjusted Total × (Fiberglass % / 100)
Matrix = Adjusted Total − Fiberglass
Base Resin = Matrix ÷ (1 + Hardener Ratio / 100 + Filler % / 100)
Base Resin = Matrix ÷ (1 + Catalyst % / 100 + Filler % / 100)
Hardener or Catalyst = Base Resin × Ratio / 100
Filler = Base Resin × Filler % / 100
Area (m²) = Total Mass (kg) ÷ [Density (kg/m³) × Thickness (m)]
The gel time shown is an indicative planning estimate only. Actual cure behavior depends on product chemistry, manufacturer recommendations, surface temperature, humidity, and batch size.
How to Use This Calculator
- Enter the project name so exported files stay easy to identify.
- Choose epoxy, polyester, or vinyl ester to match the resin system being used on site.
- Select the batch unit and enter the target finished wet batch amount.
- Set the fiberglass percentage for the laminate weight share you want to achieve.
- Add any filler percentage applied to the base resin.
- Choose a preset ratio or enter a custom hardener or catalyst value.
- Add a waste allowance for trimming, roller loss, cup residue, or rework.
- Enter temperature, laminate thickness, and density for area and working-time estimates.
- Submit the form to show the result above the form, review the chart, then export to CSV or PDF.
Example Data Table
| Project | Resin system | Target batch | Fiberglass % | Ratio | Waste % | Typical use |
|---|---|---|---|---|---|---|
| Concrete crack laminate | Epoxy | 8 kg | 40% | 100:45 | 5% | Structural patching |
| Pipe wrap reinforcement | Epoxy | 12 kg | 42% | 100:50 | 8% | Containment wrap |
| Tank wall repair | Polyester | 15 kg | 35% | 1.5% | 10% | General laminate work |
| Panel resurfacing | Vinyl ester | 10 kg | 38% | 2.0% | 6% | Chemical resistance upgrade |
FAQs
1) What does fiberglass percentage mean here?
It represents the reinforcement share of the finished wet laminate by weight. Higher values reduce resin demand, but excessively high fiber loading can make wet-out difficult and weaken the finished laminate.
2) Should I use weight or volume for mixing?
This calculator works on batch weight. Weight-based mixing is usually more reliable for construction repairs because it reduces density-related errors and keeps hardener or catalyst proportions more consistent.
3) Can I use custom resin ratios?
Yes. Select the custom option and enter your required hardener or catalyst value. Use the exact ratio from the manufacturer’s technical data sheet whenever a product has a fixed mixing requirement.
4) Why include waste allowance?
Waste allowance covers roller absorption, trimming, spillage, cup residue, oversaturation, and rework. It helps you order and batch enough material without stopping work midway through a repair.
5) Is the gel time exact?
No. It is a planning estimate only. Actual working time changes with chemistry, pot size, temperature, humidity, surface condition, and site handling. Always verify curing guidance from the product supplier.
6) What filler percentage should I enter?
Enter the filler or additive load applied to the base resin. If no filler is used, enter zero. Common examples include silica, microspheres, or thickening powders added for application control.
7) Does coverage area include overlaps and trimming?
The coverage estimate is theoretical. Overlaps, surface roughness, edge losses, and roller waste can reduce real coverage. That is why using a separate waste allowance is strongly recommended.
8) Can this calculator replace product instructions?
No. It is a practical planning tool for batching and estimating laminate composition. Final mixing, safety, curing, and application procedures must follow the manufacturer’s documented instructions.