Pour volume

Mix too little and you end up mixing a second batch mid-pour, which leaves a visible line where the batches meet. Mix too much and you've wasted the most expensive thing in the shop. The volume is just the mold's footprint times the depth, minus whatever wood or objects are sitting in it. This page does that geometry exactly and keeps the waste allowance as a separate, visible line.

Shape

Rectangle Cylinder River table

Units

Length Width Depth

Adjustments

Embedded objects, mL Volume of anything else in the pour. Measure it by water displacement. Waste margin, % ² Cup residue, leaks, soak-in. Shown separately.

Split at your ratio

Ratio Stated

Resin SG, g/mL ³ Hardener SG, g/mL

Notes

River table volume is the length × the average gap × the depth. That equals the mold volume minus the wood sitting in it. Averaging is exact for straight tapers. For a live edge, the more points you measure, the closer the estimate gets. Bark pockets and undercuts below the surface will take extra resin, and that's part of what the margin covers.
There's no standard waste margin. Common advice runs from 5 to 15%. The exact volume above is what the mold holds. The planned volume adds your margin on top. Bare wood also soaks up resin, and a seal coat brushed on first cuts both the soak-in and the bubbles that rise out of the wood.
Specific gravities only affect the gram figures. Use the numbers from your product's data sheet.
US fluid ounces and US gallons. Imperial units differ by about 4%.