Rechner für Kies & Mulch

How to use it: enter the area's length and width, how deep you want the material spread, and the bag size you plan to buy. The tool converts area × depth into volume and then into a bag count.

Formula. Length and width are in metres and depth is in millimetres, so depth is converted to metres before multiplying:

volume (m³) = length × width × (depth ÷ 1000)

Volume in litres is volume (m³) × 1000, and bags needed is that litre figure divided by bag size and rounded up, since you can't buy a fraction of a bag:

bags = ceil(volume in litres ÷ bag size in litres)

Worked example. With the defaults above (6 m × 3 m area, 50 mm deep, 25 L bags): volume = 6 × 3 × (50 ÷ 1000) = 6 × 3 × 0.05 = 0.900 m³, which is 900 L. 900 ÷ 25 = 36 exactly, so the tool reports 36 bags with nothing left over. 0.9 m³ is also about 0.9 × 1.30795 ≈ 1.177 yd³.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Length

6 m

Width

3 m

Depth

50 mm

Bag size

25 L

Primary result: Volume: 0.900 m3.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

This is a loose-fill geometric estimate - it doesn't model compaction. Gravel, mulch and soil settle and compact differently by material, so the volume you spread loose is not the same as the volume once it's settled or walked on; ask your supplier for a compaction or coverage factor for your specific material.

It also assumes a flat, rectangular area at a uniform depth - it doesn't account for slopes, irregular shapes, edging that displaces material, or extra depth needed at the edges of a bed. Bagged material coverage varies by product density, so confirm the actual volume per bag with the label or supplier rather than assuming a round number.