Epoxy Calculator

Calculate epoxy resin for coatings and pours

This epoxy calculator estimates the amount of mixed resin and hardener needed for a surface coating or a deeper pour. Enter the length and width of the work area, then choose a calculation method. For a coating, use the product's coverage per gallon or litre and enter the number of coats. For a pour, enter the planned depth. Add extra surface area, a waste allowance, the resin-to-hardener mix ratio, and the kit size to get a practical purchase estimate.

The calculator reports total mixed epoxy, separate resin and hardener volumes, and the number of kits to buy after rounding up to a whole kit. You can use feet and gallons or metres and litres. An optional price field estimates material cost. These features are useful when planning an epoxy table top, countertop coating, small floor area, craft project, river table, or a mold pour.

Epoxy products differ. They do not all share the same coverage, maximum pour depth, mix ratio, cure time, or application method. Read the technical data sheet and product label before you start. This calculator is a quantity planner, not a product selector or structural design tool.

How to use the epoxy resin calculator

Select the measurement units and project method. Choose Surface coating when applying one or more thin layers, such as a table top finish or floor coating. Enter the product's coverage per unit for one coat and set the coat count. Choose Pour by depth for filling a tray, casting a mold, or calculating the volume in a river table channel. Enter the average pour depth for that space. The pour method calculates volume directly from area and depth.

Enter length and width for the main rectangular area. If the shape includes a separate section that needs epoxy, add its surface area in the extra area field. For an irregular project, split it into rectangles and sum their areas. Use the same area units shown on screen. Measure the inside dimensions of a mold or channel rather than its outside dimensions, and account for inserts or objects that displace volume when the project needs a closer estimate.

Set the mix ratio using the manufacturer's stated resin-to-hardener ratio by volume. For example, a 1:1 mix has one part resin and one part hardener; a 2:1 mix has two parts resin to one part hardener. Enter the kit's total mixed volume as its kit size. If the package lists separate resin and hardener containers, add their volumes to get the total mixed volume. Enter price per gallon or litre only if you want a rough material cost.

Epoxy volume formulas

For a surface coating, the calculator divides total surface area by the product coverage per coat. It multiplies that amount by the number of coats, then adds the selected waste allowance. For a pour, the calculator multiplies surface area by average depth and converts the cubic measure into gallons or litres. It then adds waste. Resin and hardener are divided from the mixed volume according to the ratio entered.

The waste allowance is added after calculating the base amount. It provides a buffer for residue left in mixing cups, small spills, uneven edges, and measurement variation. It cannot correct a wrong depth, incorrect coverage, or an unsuitable resin system. A large deep pour may need a special casting resin, staged pours, or other project-specific steps; follow the product's limits rather than relying on a larger quantity estimate.

• Coating volume per coat = total surface area ÷ product coverage per unit
• Coating mixed volume = volume per coat × number of coats
• Pour volume = area × depth, converted to gallons or litres
• Mixed epoxy to prepare = base volume × (1 + waste percentage ÷ 100)
• Resin volume = mixed epoxy × resin parts ÷ total mix parts
• Hardener volume = mixed epoxy × hardener parts ÷ total mix parts
• Kits to buy = mixed epoxy ÷ kit volume, rounded up

Worked example: epoxy coating for a table

Suppose a table surface is 6 feet long and 3 feet wide. Its area is 18 square feet. The selected coating lists coverage of 50 square feet per gallon per coat, and the project needs two coats. One coat uses about 18 ÷ 50, or 0.36 gallon. Two coats use 0.72 gallon before waste. With a 10 percent allowance, the estimated mixed amount becomes about 0.79 gallon.

If the product is sold as one-gallon kits, the calculator rounds the purchase amount up to one kit. If the manufacturer specifies a 1:1 volume ratio, the 0.79 gallon working estimate consists of approximately 0.395 gallon of resin and 0.395 gallon of hardener. This example assumes the coverage figure is per coat and that both components are sold in a correctly matched kit. Follow your exact product instructions and measure the components accurately.

Worked example: calculate a deep pour

For a river table channel that is 8 feet long and 8 inches wide, convert the width to feet: 8 ÷ 12, or about 0.667 foot. The surface area is 8 × 0.667, or about 5.33 square feet. If the channel's average depth is 1.5 inches, convert depth to feet: 1.5 ÷ 12, or 0.125 foot. The volume is about 5.33 × 0.125 = 0.667 cubic foot. Since one cubic foot is about 7.48 US gallons, the base pour volume is about 5 gallons before allowance.

This is a large pour and illustrates why exact mold dimensions and the resin manufacturer's maximum pour depth matter. A deep-pour product may need a lower temperature, a specific batch size, or multiple pours. A regular table-top coating resin may overheat or fail when used in a deep mold. The calculator estimates the volume only; it does not confirm that a specific product is safe or suitable at that depth.

Coverage, pour depth, and surface texture

Coverage varies with resin viscosity, application thickness, surface texture, porosity, and the application method. A thin seal coat on porous wood may soak into the surface and use more material than a smooth sealed panel. A flood coat is thicker and covers less area per gallon than a thin coating. Always enter coverage for the coat thickness and method you intend to use, not a generic coverage number from a different product.

For a pour, a small depth error can change the required volume noticeably across a large surface. Measure multiple points if the base is uneven and use a reasonable average depth. Account for sloped sides and irregular cavities with several smaller sections. Mold walls, dams, and joints should be sealed so liquid resin does not escape. Inserts, stones, wood slabs, and other objects may displace resin; subtract their volume if you can measure it accurately.

Understanding epoxy mix ratios

A mix ratio states how much resin and hardener to combine. The ratio may be written as resin first and hardener second, such as 1:1, 2:1, 3:1, or 5:1. A 2:1 ratio by volume means two equal volume parts of resin for every one volume part of hardener. The calculator uses the order resin:hardener and divides the total mixed amount into those parts.

Some products specify a ratio by weight rather than by volume. Weight and volume are not interchangeable because resin and hardener can have different densities. This calculator's mix ratio is by volume. If the product gives a weight ratio, use a scale and follow its weight-based instructions; do not enter that ratio here as though it were a volume ratio. Never change a product's specified ratio to make it cure faster or slower.

Accurate measuring and thorough mixing matter. Scrape the sides and bottom of the mixing container as directed. Some systems recommend transferring to a clean second container and mixing again. Unmixed material can remain soft or sticky. Mix only a batch size that you can apply within the working time stated for the product and conditions.

Choose the right resin for your project

Table-top epoxy is designed for relatively thin coating applications and a clear, smooth finish. Casting or deep-pour epoxy is designed for thicker sections within the manufacturer's stated depth limits. Flooring epoxy, laminating resin, marine epoxy, and craft resin have different properties and intended uses. A calculator can estimate a quantity but cannot decide which formula is appropriate for heat, sunlight, food contact, outdoor exposure, structural bonding, or chemical resistance.

Check whether the resin is compatible with the substrate and any tint, pigment, embedded object, or previous coating. Review maximum pour depth, batch size, temperature range, cure schedule, UV guidance, and ventilation requirements. Large masses of curing epoxy can produce heat. The product data sheet explains the safe application limits for that formulation.

Account for waste and kit sizes

Epoxy left on the walls of a mixing bucket or spreader cannot always be used on the surface. A modest waste allowance can cover this residue and small spills. The suitable percentage depends on project shape, batch handling, surface porosity, and experience. A clean rectangular panel may need less allowance than a complex mold with corners, dams, and multiple pours.

Kit sizes are not always simple one-gallon totals. A kit may contain a resin can and a smaller hardener can, or be sold by weight. Enter the total mixed volume only when the package provides a compatible volume basis. If you buy separate containers, make sure they are the correct paired resin and hardener sizes and that the calculated amount follows the specified ratio. Round up to a full kit, but avoid opening more material than you can store and use safely.

Surface preparation and application planning

A clean, dry, stable surface is important for a good epoxy finish. Remove dust, oil, loose material, and contaminants using the method recommended for the substrate and resin. Seal porous wood when required to reduce bubbles from air escaping through the grain. Mask edges and prepare dams or a level mold before mixing. Gather mixing cups, stir sticks, spreaders, gloves, and other protective equipment in advance.

Temperature affects viscosity, working time, and cure. A warmer room may shorten pot life; a cooler one may slow curing or make resin harder to spread. Follow the manufacturer's temperature range for the product and substrate. Avoid mixing a large batch in a deep container unless instructions allow it, because mixed resin can heat up faster when concentrated. Work in a ventilated space and use the personal protective equipment specified in the safety data sheet.

Common epoxy measuring mistakes

One common error is multiplying the surface area by a coat thickness without converting units. If the area is in square feet and the depth is in inches, convert inches to feet before calculating cubic feet, then convert cubic feet to gallons. This calculator performs that conversion for a pour. In metric units, square metres multiplied by millimetres gives litres numerically, which makes the metric pour calculation straightforward.

Another mistake is applying the mix ratio to the total volume incorrectly. For a 2:1 mix, the total has three parts: two parts resin and one part hardener. It does not mean two parts resin plus two parts hardener. Also make sure the ratio is by volume if using the calculator. Using the wrong ratio can prevent a proper cure and waste the entire project.

Do not rely on the manufacturer's maximum coverage to promise a finish thickness or final yield. Real surfaces absorb material, and pours may lose volume to leaks or irregular voids. Use the exact product coverage, measure accurately, and test the process on a small area when practical.

Frequently asked epoxy calculator questions

How much epoxy resin do I need? For a coating, divide the area by the product's coverage per coat and multiply by the number of coats. For a pour, multiply area by depth and convert to a volume. Add an allowance for waste, then split the mixed total by the manufacturer's resin-to-hardener ratio. How much epoxy for a table? Measure its top length and width, add any edges that will be coated, and use the exact product coverage and coat thickness.

How many square feet does one gallon of epoxy cover? It depends on the epoxy and coating thickness. A thin seal coat covers more area than a thicker flood coat. Read the product's coverage information and check whether it describes one coat or a complete system. What is a 1:1 epoxy mix ratio? It means equal parts resin and hardener using the measurement method stated by the manufacturer, which may be volume or weight.

Can I use this for a river table? Yes, to estimate the volume from the channel area and average depth. Confirm that the resin is made for deep pours and that the depth, batch size, temperature, and curing conditions stay within its instructions. Can I use it for epoxy flooring? Yes, as a material quantity estimate if you enter the floor dimensions, coverage per coat, and coat count for the specific floor system.

Use the product instructions for the final plan

A helpful epoxy estimate combines accurate dimensions with the right coverage or depth, coat count, waste allowance, mix ratio, and kit size. Measure irregular areas carefully, use one unit system throughout, and check that the label's coverage is per coat. The calculator's resin and hardener split follows the volume ratio you enter, so verify that your product specifies a volume ratio before using those values.

Before mixing, read the product data sheet and safety directions from start to finish. Confirm maximum pour thickness, batch size, temperature, pot life, curing time, surface preparation, and protective equipment. The calculator helps plan quantity; the manufacturer's instructions control how that epoxy should be measured, mixed, poured, and cured.