How Much Resin Do I Need?
Epoxy is measured by volume, so a pour is just length times width times thickness — the volume of the space you're filling or coating. The calculator computes that in cubic inches and converts to fluid ounces, then splits the total into resin and hardener according to your kit's mix ratio. Enter a thin thickness like an eighth of an inch for a surface coating, or the full mold depth for a casting.
Get the ratio exactly right
Unlike paint, epoxy ratios aren't approximate. A 1:1 or 2:1 kit must be mixed at that ratio precisely, or it won't cure — you'll get soft, sticky, or tacky spots that never harden. Measure by the method your kit specifies (usually volume) and mix thoroughly, scraping the sides and bottom of your container, since unmixed resin clinging to the cup is a common cause of soft patches.
Mind the depth and the heat
Curing epoxy is exothermic — it generates heat — and thick pours can overheat, yellow, crack, or even smoke. Every resin has a maximum single-pour depth, often around half an inch to two inches depending on the formula; deep casting resins allow more. For anything deep, pour in layers within the product's limit. Always mix a little extra beyond the calculator's figure to account for what stays behind on your cup and stir stick.
Frequently asked questions
- How do I calculate resin for a table top?
- Multiply length by width by coating thickness (like 0.125 in), then convert to ounces — this tool does it for you.
- What happens if I mix the ratio wrong?
- The epoxy may never fully cure, leaving soft or sticky spots. Ratios must be followed precisely.
- Why can't I pour resin very deep?
- Curing generates heat; too-deep pours overheat and can yellow or crack. Pour in layers within your kit's depth limit.