CoverCalcPRO

One footprint · two material orders

Raised Bed Soil and Mulch Calculator

Measure the inside of each bed once. Set the soil fill and mulch cap you plan to add, then calculate each product separately.

Worked example · sample inputs One 4 × 8 ft bed 10 in soil fill → 26.67 ft³ → 18 × 1.5 ft³ bags 2 in mulch cap → 5.33 ft³ → 3 × 2 ft³ bags Arithmetic example only; depths and package sizes are not recommendations.
Cross-section of one measured raised-bed footprint with a separately measured soil fill depth and mulch cap depth.

01 Measure each bed

Enter usable inside dimensions in feet and both depths-to-add in inches. A zero depth is allowed.

02 Match each product label

Bag volumes are separate. Leave a price blank when you do not have a quote.

Soil fill
Mulch cap

Enter both prices in the same currency. The currency symbol is not converted.

Inside measurementsSeparate depth per materialSeparate package roundingCalculates in your browser

Calculation method

One measured footprint, two separate volumes

For each rectangular bed, area is length × width. Soil volume and mulch volume are then calculated independently: area × the selected material's depth-to-add. If different beds need different amounts, put each bed on its own row.

US: square feet × depth in inches ÷ 12 = cubic feet

Metric: square metres × depth in centimetres ÷ 100 = cubic metres

To convert cubic feet to cubic yards, divide by 27. To convert cubic metres to litres, multiply by 1,000. Bag counts use the volume printed on each product, with soil and mulch rounded separately.

Source notes: Iowa State University Extension describes area × depth and whole-bag rounding for mulch. NIST Handbook 44, Appendix C lists the unit conversions used here. Depth selection, soil mix and product choice remain yours.

Worked arithmetic

Example: the same 4 × 8 ft bed

The footprint is 32 ft². With a sample 10 in soil depth, 32 × 10 ÷ 12 = 26.67 ft³; 26.67 ÷ 1.5 ft³ per bag rounds up to 18 bags. With a separate sample 2 in mulch depth, 32 × 2 ÷ 12 = 5.33 ft³; 5.33 ÷ 2 ft³ per bag rounds up to 3 bags.

These are example inputs for checking the arithmetic. The page does not recommend either depth or either bag size.

Common questions

Raised bed soil and mulch FAQ

How do I calculate soil and mulch for the same raised bed?

Measure the usable inside length and width once. For each material, multiply the bed area by that material's depth-to-add. This calculator totals soil and mulch separately, then uses each product's own package volume to round up whole bags.

Does this calculator recommend a soil or mulch depth?

No. Enter the amount you plan to add for each material. The page does not prescribe a soil fill depth, mulch depth, soil recipe or plant-specific practice.

Can different beds use different depths?

Yes. Add one row per rectangular bed and enter its inside length, width, soil depth-to-add and mulch depth-to-add. The calculator sums each material independently.

How are the bag counts calculated?

Divide each material's volume by the volume printed on that material's package, then round up to a whole package. Soil and mulch use separate label volumes and separate rounding.

Can I compare the cost of soil with mulch?

Enter a bag price for each product if you have one. Each total multiplies that product's entered price by its own whole-bag quantity. The calculator does not supply market prices.

Continue planning

Keep the measurements with the rest of the project

For a soil-only purchase, use the raised bed soil calculator to compare bags and bulk volume. For a fill already chosen as multiple ingredients, use the raised bed soil blend calculator to split each component into its own package count. For separate mulch-depth planning, use the mulch depth and top-up calculator. If you are estimating an open garden area, start with the mulch calculator, then continue to the mulch project planner to organize measurements and orders.