How much soil do I really need?

When considering how much soil to get to fill a raised bed, the calculator to the left can give you a good estimate of what you’ll need in terms of typical bags, cubic feet, cubic yards, or liters.

You might be tempted to get a little less soil than it recommends since you probably won’t want to fill your bed to the absolute top edge, but in doing so, you’ll want to keep a couple of things in mind. First, soil measurements are rarely precise. The variances won’t matter much in a small bed, but in a larger one, that can add up to actually needing more than the calculator recommends.

Secondly, soil will compact over time. As time goes on, soil materials will break down, the pores in your soil will compact, and as a result, the level of soil in the bed will go down. You’ll need to cultivate and backfill the soil to maintain a good level in the bed. If you start out with a lower level to begin with, that just means you’ll either end up with too little soil for certain crops or have to do more work later to keep the level where it needs to be.