Soil and Mulch Calculators
Three small calculators for the questions every gardener hits each spring: how much mulch or soil does this bed take, what goes into a raised bed mix, and how many plants fit at the spacing on the packet. Enter your measurements and the math is done on the spot, in US and metric units. Nothing here needs an account, and no result pages are created.
Mulch and soil volume
Measure the bed, pick a depth, and get the volume three ways: cubic feet, cubic yards (what bulk deliveries are sold by), and 2-cubic-foot bags (the standard bag size at garden centers). The order figure adds roughly 10 percent, because mulch settles and fluffed material compacts once it is spread and watered; order that much extra rather than running short mid-bed. Depths of 2 to 3 inches are typical for mulch, and 3 to 4 inches where weeds are the main problem.
Raised bed soil mix
The classic raised bed mix is three equal parts: topsoil for body and minerals, compost for fertility and life, and an aeration material such as coarse perlite, pine bark fines, or coconut coir to keep the mix from packing down. Enter the inside measurements of the bed and the fill depth, and the calculator splits the total volume into those thirds. Mixes vary: gardeners with excellent local topsoil often use less of it and more compost, sandy soils may need no extra aeration, and some published recipes use a 60/30/10 split instead. Treat the thirds as a sound starting point, and adjust for the soil you are starting from.
Plant spacing
Count how many plants fit in a bed at a chosen spacing. On a square grid, each plant gets a square of bed as wide as the spacing, so the count is the bed area divided by that square. Offset rows shift every other row by half a spacing, which packs plants on triangles: each plant effectively uses about 87 percent of the square, so roughly 15 percent more fit at the same spacing. Either way this is a planning estimate, not a promise: paths, edges, and the odd corner all take their share. The spacing itself comes from your seed packet or an extension planting guide for the crop and variety, not from us, and wider spacing is the right call for plants that need airflow or room to sprawl.
About these calculators
The volume math is length times width times depth, the same arithmetic bulk yards and extension guides use, with 27 cubic feet to a cubic yard and 28.3 liters to a cubic foot. Bag counts round up, because bags are sold whole, and the raised bed thirds and the spacing layouts are stated in full above so you can check any figure by hand. Planning a planting to go in these beds? Pair this page with the Seed Starting and Transplant Calculator for dates and the hardiness zones guide for what will survive your winter.