Epoxy Mix Ratio Calculator

Calculator

Calculation mode

Ratio basis

Batch amount

Resin parts

Hardener parts

Waste allowance (%)

Input weight unit

Input volume unit

Output weight unit

Output volume unit

Resin density (g/ml)

Hardener density (g/ml)

Coverage length

Coverage width

Length and width unit

Coating thickness

Thickness unit

Number of coats

Resin cost per kg

Hardener cost per kg

Scale precision (g)

Example Data Table

Project	Ratio	Basis	Target	Waste	Use Case
Small jewelry cast	1:1	Volume	120 ml	5%	Clear mold pour
Table coat	2:1	Weight	1.5 kg	8%	Surface coating
Fiberglass repair	3:1	Weight	500 g	10%	Fabric wet out

Formula Used

Total parts = Resin parts + Hardener parts.

Resin amount = Total amount × Resin parts ÷ Total parts.

Hardener amount = Total amount × Hardener parts ÷ Total parts.

Waste adjusted amount = Base amount × (1 + Waste percent ÷ 100).

Coverage volume = Length × Width × Thickness × Coats.

Weight from volume = Volume × Density.

Volume from weight = Weight ÷ Density.

For coverage with a weight ratio, the calculator solves material weight from density. It uses: k = Total volume ÷ ((Resin parts ÷ Resin density) + (Hardener parts ÷ Hardener density)).

How to Use This Calculator

Select whether your epoxy label gives the ratio by weight or by volume.
Enter resin parts and hardener parts, such as 2 and 1.
Choose a calculation mode for total batch, resin, hardener, or coverage.
Enter density values when you need weight and volume conversion.
Add waste for cups, brushes, rollers, and surface loss.
Press the calculate button.
Use the CSV or PDF buttons to save the result.

Epoxy Mix Ratio Guide

Why Accurate Mixing Matters

Epoxy works because resin and hardener react in a fixed balance. A small mistake can leave soft spots, cloudy areas, weak bonds, or excess heat. This calculator helps you plan the batch before you open containers. It supports ratios by weight or by volume, because product labels may use either method. Always follow the manufacturer label first.

Planning a Better Batch

Start by choosing the ratio basis. A 2:1 volume ratio is not always the same as a 2:1 weight ratio. Resin and hardener often have different densities. The tool lets you enter density values, so it can estimate both grams and milliliters. This is useful when you measure with a scale, but still want to know cup or syringe volumes.

Waste allowance is also important. Brushes, cups, rollers, and uneven surfaces keep some material. Add a small waste percent for coating work. Use a larger allowance for rough wood, fabric wet out, or complex molds. The coverage mode multiplies length, width, thickness, and coat count. It then applies waste before splitting the mix.

Using Results Safely

Measure each component in a clean container. Tare the scale before adding resin. Add hardener slowly until the calculated amount is reached. Scrape the cup sides and bottom while mixing. Transfer the blend into a second cup when accuracy matters. Mix again to reduce unmixed streaks.

Do not change the ratio to speed curing. Extra hardener usually weakens the result. Temperature, product chemistry, and batch size affect cure speed. Large batches can heat faster than thin coatings. Divide large pours into smaller batches when pot life is short.

Common Applications

This calculator helps with art resin, table coatings, fiberglass repair, adhesives, mold casting, and protective sealing. It is also helpful when scaling test batches into larger projects. Save the CSV file for job notes. Use the PDF result for shop records or client estimates.

A careful mix improves finish quality. It reduces waste. It also makes repeat work easier. Keep notes about temperature, brand, surface type, and final hardness. These details help you repeat a successful pour later. They also show when a ratio, density value, or waste setting needs careful adjustment again.

FAQs

What is an epoxy mix ratio?

It is the required proportion of resin to hardener. Common ratios include 1:1, 2:1, 3:1, and 5:1. Use the ratio printed on your product label.

Should I measure epoxy by weight or volume?

Use the method recommended by the manufacturer. Weight is usually more precise. Volume can work well when the label gives a volume ratio.

Why do density values matter?

Density converts between grams and milliliters. Resin and hardener may not weigh the same per milliliter. Accurate density improves cross-unit estimates.

Can I add extra hardener for faster curing?

No. Extra hardener can weaken the cured material. It may also leave sticky spots. Use temperature control or a faster product instead.

What waste percentage should I use?

Use 3% to 5% for simple cup mixing. Use 8% to 15% for brushes, rollers, fabric, rough wood, or complex molds.

Why is my epoxy still sticky?

Sticky epoxy often comes from wrong ratio, poor mixing, low temperature, or contaminated surfaces. Check the ratio and mix longer next time.

Can this calculator handle surface coating?

Yes. Choose coverage mode. Enter length, width, thickness, and coats. The calculator estimates total volume before splitting resin and hardener.

Is the PDF result saved on the server?

No. The PDF is created in your browser. It is meant for quick records, job notes, and simple project documentation.