Free & Instant — No Signup Required

Epoxy Ratio Calculator

Calculate precise resin-to-hardener volumes for any epoxy system. Select your ratio type (1:1, 2:1, 3:1, or 5:1), toggle between weight and volume measurement, and get exact amounts for a perfect chemical cure.

Epoxy Ratio Calculator — Live Preview
Hardener Needed
—
Resin
Hardener

Widgets

Quick interactive ratio calculators — solve proportions, scale values, and simplify ratios.

Proportion Solver

Provide any three values below to calculate the fourth in the ratio A : B = C : D.

:
=
:
Solved Proportion
—
Simplified
—
Percentages
—
Decimal
—
Fraction
—
Visual Ratio
A
B
Part A: —
Part B: —

    Scale Multiplier

    Scale a ratio up or down by a multiplier.

    :
    Scaled Ratio
    —
    Original
    —
    Factor
    —
    Percentages
    —
    Simplified
    —
    Visual Ratio
    A
    B

      Simplifier

      Reduce any ratio to its simplest form.

      :
      Simplified Ratio
      —
      GCD Used
      —
      Percentages
      —
      Decimal
      —
      Fraction
      —
      Visual Ratio
      A
      B
      Part A: —
      Part B: —

        🕐 Recent Calculations

        📭
        No calculations yet. Start computing above!

        What Are Epoxy Mix Ratios?

        An epoxy mix ratio defines the proportion of resin to hardener needed for a complete chemical reaction. Unlike paint that simply dries by solvent evaporation, epoxy undergoes a chemical cure — resin molecules cross-link with hardener molecules in a specific stoichiometric ratio. Getting this ratio wrong means some molecules remain unreacted, leaving the cured epoxy soft, tacky, or brittle.

        Common epoxy ratios include 1:1 (craft and table-top epoxies), 2:1 (general-purpose laminating systems), 3:1 (structural adhesives), and 5:1 (high-performance marine and aerospace epoxies). The ratio can be specified by volume or by weight — these are not interchangeable because resin and hardener have different densities. This Epoxy Ratio Calculator handles both measurement methods.

        Formulas & Equations Used

        This Epoxy Ratio Calculator uses the following core equations:

        1Hardener from Resin Volume▼
        Hardener = Resin Volume ÷ Resin Ratio × Hardener Ratio

        For a 2:1 ratio with 200 ml resin: Hardener = 200 ÷ 2 × 1 = 100 ml.

        2Total Mixed Volume▼
        Total = Resin + Hardener

        200 ml resin + 100 ml hardener = 300 ml total epoxy. Account for ~5% volume loss during mixing and application.

        3Volume to Weight Conversion▼
        Weight = Volume × Density (Resin ≈ 1.10-1.15 g/ml, Hardener ≈ 0.95-1.05 g/ml)

        200 ml resin at 1.12 g/ml = 224g. Volume ratios differ from weight ratios due to density differences.

        4Coverage Area Estimate▼
        Area = Total Volume ÷ Desired Thickness

        300 ml of mixed epoxy at 1mm thick covers approximately 3,000 cm² (about 3.2 sq ft).

        How to Use This Epoxy Ratio Calculator

        Follow these 3 simple steps:

        1

        Select Ratio Type

        Choose your epoxy system ratio (1:1, 2:1, 3:1, or 5:1) and whether you're measuring by weight or volume.

        2

        Enter Resin Amount

        Type in how much resin you plan to use. The calculator computes the exact hardener amount to maintain the stoichiometric ratio.

        3

        Get Exact Measurements

        View the hardener amount, total mixed volume, coverage area estimate, and a visual proportion bar showing the resin:hardener split.

        Example Problems & Step-by-Step Solutions

        Here are 3 worked examples using this Epoxy Ratio Calculator:

        Example 1Mix 500 ml of 2:1 epoxy for a river table
        1 Ratio: 2 parts resin : 1 part hardener (by volume)
        2 Hardener needed: 500 ÷ 2 × 1 = 250 ml
        3 Total volume: 500 + 250 = 750 ml
        4 Coverage at 6mm thick: 750 ÷ 0.6 = 1,250 cm² (1.35 sq ft)
        ✓ Mix 500 ml resin + 250 ml hardener = 750 ml total epoxy
        Example 2Calculate by weight: 300g resin at 100:45 (weight ratio)
        1 Weight ratio: 100 parts resin : 45 parts hardener
        2 Hardener = 300 × (45 / 100) = 135g
        3 Total weight: 300 + 135 = 435g
        ✓ Weigh 300g resin + 135g hardener = 435g total
        Example 3Need 1 liter total of 1:1 epoxy
        1 Ratio: 1:1 — equal parts resin and hardener
        2 Resin = 1000 × 1/2 = 500 ml
        3 Hardener = 1000 × 1/2 = 500 ml
        ✓ Mix 500 ml resin + 500 ml hardener = 1,000 ml (1 liter)

        Interactive Epoxy Mixer

        Select your epoxy ratio preset, adjust the resin volume, and see exact hardener amounts with a live proportion bar. Toggle between weight and volume measurement for accurate results.

        🧪
        Resin
        200 ml
        +
        ⚗️
        Hardener
        100 ml
        =
        📦
        Total
        300 ml
        Resin
        Hardener

        Common Epoxy Ratios by Application

        Different epoxy applications require different ratio systems. Always check the manufacturer's technical data sheet for the exact ratio and whether it's specified by weight or volume.

        ApplicationTypical RatioMeasurementPot Life
        Craft / Table-Top Coating1:1By Volume30-45 min
        River Table / Deep Pour2:1By Volume45-60 min
        Laminating / Fiberglass5:1By Weight20-40 min
        Structural Adhesive3:1By Weight15-30 min
        Marine Coating2:1By Weight30-50 min
        Floor Coating2:1By Volume25-40 min

        Frequently Asked Questions

        What is the most common epoxy mix ratio?▼

        The most common ratio is 1:1 by volume (equal parts resin and hardener). Many craft, jewelry, and table-top epoxies use this simple ratio. Industrial laminating and marine systems often use 2:1 or 5:1 ratios by weight for different working properties.

        What happens if I use too much hardener?▼

        Excess hardener causes the epoxy to cure too fast, generate excessive heat (exothermic reaction), become brittle, and may turn yellow. The surface may remain tacky because unreacted hardener stays on top. Always measure carefully — even a 10% deviation can cause problems.

        Is epoxy ratio measured by weight or volume?▼

        It depends on the product. Some specify by volume (easier to measure with graduated cups), others by weight (more precise using a scale). Always check the technical data sheet — a 2:1 by volume ratio is different from 2:1 by weight because resin and hardener have different densities.

        How accurate does my epoxy mix need to be?▼

        Most epoxies tolerate ±5% deviation from the specified ratio. Beyond that, curing problems occur. Use calibrated measuring cups for volume, or better yet, a digital scale for weight. Stir thoroughly for at least 3-5 minutes, scraping sides and bottom.

        Why is my epoxy still sticky after 24 hours?▼

        Tacky epoxy usually means the ratio was wrong, components weren't mixed thoroughly, or the temperature was too cold (below 60°F/15°C). Try warming the surface with a heat gun. If it remains tacky after 72 hours, scrape it off, clean the surface, and remix with the correct ratio.

        Learn About Ratios

        What is a ratio?

        A ratio is a comparison between two or more quantities showing the relative size of one to another. Written as A : B, it means 'for every A units of the first quantity, there are B units of the second.' For example, a ratio of 3 : 4 means for every 3 parts of A, there are 4 parts of B. Ratios are used in cooking, construction, finance, science, and everyday life.

        How do I solve a proportion?

        A proportion is an equation that says two ratios are equal: A : B = C : D. To solve for a missing value, use cross-multiplication. If D is unknown: D = (B × C) / A. This works because in equal ratios, the cross products are always equal: A × D = B × C. Our Proportion Solver does this automatically — just enter any 3 values and it finds the 4th.

        How do I simplify a ratio?

        To simplify a ratio, find the Greatest Common Divisor (GCD) of both numbers and divide each by it. For example, 24 : 36 — the GCD of 24 and 36 is 12. So 24 ÷ 12 = 2 and 36 ÷ 12 = 3, giving the simplified ratio 2 : 3. Our Simplifier automatically finds the GCD and reduces your ratio to its lowest terms.

        What is ratio scaling and when is it useful?

        Scaling a ratio means multiplying both parts by the same factor to create an equivalent, larger (or smaller) ratio. For instance, scaling 2 : 5 by a factor of 3 gives 6 : 15. This is extremely useful for recipes (tripling a recipe), construction (scaling blueprints), mixing solutions, or any scenario where you need to maintain the same proportion at a different magnitude.

        What's the difference between a ratio and a fraction?

        A ratio A : B compares two quantities to each other (part-to-part), while a fraction A/B typically represents a part-to-whole relationship. However, any ratio can be expressed as a fraction: 3 : 4 is equivalent to 3/4 = 0.75. The key difference is context — ratios compare quantities side-by-side, while fractions represent a portion of a total.