A 18 gallon/68 liter storage tote is the perfect measuring cup for Square Foot Gardening.
A 4 foot by 4 foot SFG requires 8 cubic feet of Mel’s Mix. 1/3 Compost, 1/3 Peat, 1/3 Vermiculite or 2.67 cubic feet of each material. A full tote equals 2.4 cubic feet. A heaping tote will be very close to the required 2.67 cubic feet. This is gardening, not rocket science, so absolute precision is not required. I’ll use three tubs, one of each ingredient, mix it on a tarp and add it the the new raised beds. I’ll make three different “dumps” because the weight does add up. I found that the store bought compost in 40 lb. bags equal about 0.75 cubic feet. This is the best way I have found to mix, measure and add the mix to a new Square Foot Garden.