Flood Coat Calculator
Calculate the amount of resin needed for flood coats on countertops, tabletops, or artwork based on surface area, thickness, and number of coats.
About this calculator
This calculator scales a manufacturer's spread rate — expressed at a reference of 1 mil thick — to whatever thickness you're actually aiming for, since a thicker flood coat naturally covers less area per ounce of resin. It divides your product's stated spread rate (typically 1.4–1.8 sq ft per oz at 1 mil) by your target thickness in mils to get the effective coverage rate at that thickness, then divides your surface area by that effective rate to get ounces needed for one coat. That per-coat figure is multiplied by the number of coats you plan to apply, and a flat 15% overage is added on top of the raw total to account for drips over the edges, mixing-cup residue, and the tendency to slightly over-pour flood coats to guarantee full edge coverage — a larger cushion than many resin calculators use because flood coats are poured generously by design.
The tool also reports total buildup thickness (thickness per coat times number of coats, converted to inches) so you can sanity-check the finished depth against your mold's edge height or pour dam. One assumption worth flagging: it treats spread rate as linear with thickness and identical across every coat, but in practice a seal coat (thin, to lock down porous surfaces) typically runs thinner than the flood coats that follow it — if you're mixing coat thicknesses, run this calculator once per distinct thickness rather than averaging them into one number.
Inputs
Results
Total Resin (with 15% overage)
207 oz
≈ 3 bags of sugar
How to Use This Calculator
- Enter the total surface area you need to coat in square feet.
- Set the target thickness per coat in mils (typical flood coats are 4–8 mils; 1 mil = 0.001 inch).
- Enter the number of coats you plan to apply.
- Enter the spread rate of your epoxy in sq ft per oz at 1 mil from the product data sheet.
- Read the total resin needed in ounces with 15% overage for drips and edge coverage.
- Use the gallons output to compare costs when purchasing resin in larger containers.
How the result changes with Spread Rate
| Spread Rate | Total Resin (with 15% overage) |
|---|---|
| 0.8 | 414 oz |
| 1.2 | 276 oz |
| 2.4 | 138 oz |
| 4 | 82.8 oz |
What each input means
- Surface Area
- Total surface area to be coated in square feet. For rectangular surfaces: length (ft) x width (ft).
- Target Thickness per Coat
- Thickness per coat in mils (1 mil = 0.001 inches). Seal coat: 3-5 mils. Standard flood coat: 10-15 mils. Heavy flood: 30-60 mils (1/16").
- Number of Coats
- Typically 1 seal coat + 1-2 flood coats. More coats build up thickness and improve durability.
- Spread Rate
- Coverage rate of your resin at 1 mil thickness. Typical epoxy covers 1.4-1.8 sq ft per oz at 1 mil. Check your product data sheet.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersSurface Area = 12, Target Thickness per Coat = 12, Number of Coats = 2, Spread Rate = 1.6 = 4 input(s) provided
- Calculate Total ResinTotal Resin207 = 207
- Calculate Total ResinTotal Resin1.617 = 1.617
- Calculate Exact Resin NeededExact Resin Needed180 = 180
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does doubling the target thickness not simply double the resin needed?
It actually does scale linearly here — the calculator divides your spread rate by the target thickness in mils to get an effective coverage rate, so doubling thickness halves that effective rate and doubles the ounces needed for the same area. What can be less intuitive is that this relationship is treated as perfectly linear across all thicknesses, which is a simplification of how resin actually levels and self-heals at very different depths.
Why is the overage on this calculator higher than on other resin calculators in this category?
Flood coat pours use a flat 15% overage, higher than the 10% used elsewhere in this category, because flood coats are deliberately poured generously to guarantee full edge-to-edge coverage and account for drips running off the sides during the pour. That extra cushion is built into the totalResinOzWithOverage figure on top of the raw calculated total.
Does the calculator account for a thinner seal coat automatically?
No — it applies the same spread rate and thickness to every coat you specify in the Number of Coats field, so it assumes uniform thickness across all coats. If your project uses a thin seal coat followed by thicker flood coats, run the calculator once for the seal coat thickness and once for the flood coat thickness rather than entering an average.
How is the total buildup thickness output useful if I already entered thickness per coat?
Total Buildup multiplies your per-coat thickness by the number of coats you're applying, converting the result to inches as well as mils, so you can directly compare the finished depth against a physical constraint like your mold's pour dam height or a countertop's edge trim — numbers you likely have in inches, not mils.
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