Garden calculators

Set your area once, then read off how much mulch, soil, plants, water and fertiliser it needs. Everything is metric, and every answer shows how it was worked out.

Your area

Length m Width m

Across (diameter) m

Base m Height (base to point) m

Area m² Edge length m

For an odd shape, split it into rectangles and triangles and add them up, or draw it in the layout planner of one of your lists, which measures it for you. Edge length is only used for edging and border plants.

Mulch

Depth mm

Bag size L Price (optional) $ $

Keep mulch a hand's width clear of stems and trunks. Fine mulches stay thinner (50 mm) so water still gets through.

Soil, compost and garden mix

Depth mm

Material Extra for settling % Bag size L

Loose soil settles by 10 to 20% once watered in. Weights vary a lot with moisture, so check with your supplier before loading a trailer.

How many plants

Spacing (centre to centre) m

Pattern Grid (rows and columns) Staggered (zigzag rows, fuller cover)

Space plants at their grown width (it's on every plant page). Go a little closer for quick cover with groundcovers, never closer for trees and large shrubs.

Watering

Water to apply mm

Hose or sprinkler flow L/min

Don't know the flow? Time a bucket

Bucket size L Seconds to fill it s

1 mm of water is 1 litre on every square metre, the same as 1 mm of rain. Water deeply and less often so roots grow down.

Fertiliser, seed, lime or gypsum

Rate on the packet g per m² Pack size (optional) kg

Many natives, especially Proteaceae like banksias and grevilleas, are sensitive to phosphorus: use a low-phosphorus native fertiliser, and less rather than more.

Liquid feed and dilution

The label says per L of water.

Your container L

Measure the product first, then fill with water so it mixes. If a label gives a ratio like 1:100, that's 10 mL per litre.

These are estimates for planning and ordering. Product labels and your supplier's advice come first.