Raised Bed Soil Calculator
This raised bed soil calculator shows how much material a raised bed needs: the total in liters, cubic feet and cubic meters, split into the classic layers of branches, leaves, compost and soil – with a settling allowance and the number of bags.
Source: Wikipedia – Raised-bed gardening. Updated: .
How it is calculated
A raised bed is filled in layers: coarse material at the bottom, fine planting soil on top. The tool calculates the volume of the bed and splits it across the layers – including an allowance, because the fill settles in the first year.
How it is calculated
Volume = length × width × fill height; for a round bed π × (diameter ÷ 2)² × fill height. The fill height is the frame height minus the gap to the top edge. A settling allowance is added, because branches and leaves rot and sink by 10–30%. For conversion: 1,000 liters make one cubic meter, and one cubic foot is about 28.3 liters.
The classic layering
- Bottom (about 30%): coarse branches and shrub cuttings for air and drainage. Wire mesh against voles goes underneath.
- Next (about 20%): leaves, turf or grass clippings that rot slowly.
- Above (about 20%): half-ripe compost as a nutrient store.
- Top (about 30%): loose planting soil in which the plants root.
The shares are rules of thumb from gardening practice, not a fixed standard. Filling with soil only saves work, but you lose the warmth and nutrient boost from rotting material inside.
Similar calculators: the mulch calculator works out mulch and soil for beds, the gravel calculator handles gravel and stone, and the volume calculator converts any shape into liters.
Frequently asked questions
How much soil do I need for a raised bed?
Length × width × fill height, in liters. A bed of 200 × 100 cm with a fill height of 70 cm holds 1,400 liters; with a 20% settling allowance it is 1,680 liters.
How high should I fill a raised bed?
About 2–4 inches below the top edge so the water does not spill over. The fill sinks in the first year and is topped up with compost every year.
Which layers go into a raised bed?
Classically from the bottom: branches, leaves or turf, half-ripe compost and planting soil on top. The table shows height and amount for each layer.
How many bags of soil is that?
The amount in liters divided by the bag content, rounded up. With 40-liter bags, 1,000 liters need 25 bags.
Why add a settling allowance?
Because branches, leaves and compost rot and noticeably sink in the first year. Without the allowance the bed would soon be underfilled.
Sources and legal basis
As of: · Editorial policy
Related tools
- Mulch CalculatorMulch calculator for beds, tree rings and raised beds: cubic feet and cubic yards with extra, plus how many 1.5, 2 or 3 cu ft bags you need. Works for soil too.
- Gravel calculatorGravel calculator: cubic meters and tons needed for a driveway, bed or drain from length, width and depth – with allowance, gravel or sand, wet or dry, cost.
- Volume CalculatorVolume calculator for 12 shapes: cylinder, box, sphere, cone, prism, horizontal tank … Mix cm, m, inches and feet – with litres, gallons, formula and sketch.
- Plant Spacing CalculatorPlant spacing calculator: how many plants fit in your bed? Rows, plants per row and per square foot – in a grid or staggered – or the spacing for a set number.
- kg to lbs converterConvert kg to lbs and back: 1 kg = 2.2046 lb. Shows pounds and ounces, stone and pounds, grams, tons and a kg to lbs chart – exact to the legal definition.
- Cubic meters to cubic feet converterCubic meters to cubic feet: multiply by 35.3147, so 10 m³ = 353.1467 ft³. Convert m³ to ft³ or back, with cubic yards, liters and a conversion chart.
- Schengen calculator for the 90/180-day ruleSchengen calculator: enter your past trips and see how many of your 90 days are used, how many are left and how long your next stay may last.
- Yeast conversion calculatorYeast conversion calculator: convert fresh (cake) yeast to active dry or instant yeast and back – in grams, ounces, packets and teaspoons.
- Bar to kPa converterBar to kPa: multiply by 100, so 2.2 bar = 220 kPa. Convert bar to kilopascals or kPa to bar, with psi, atmospheres, megapascals and a pressure chart.