Calculators
Planning a garden project in Australia means juggling numbers — how many turf rolls for the backyard, how much mulch to cover a bed, how big a rainwater tank you actually need, or how much lime to correct your soil pH. Guessing usually means over-ordering and wasting money, or under-ordering and making a second trip to the garden centre. Garden Green’s free calculators take the guesswork out. Each tool is built for Australian conditions — metric measurements, local climate zones, native species, and the soil and water realities of QLD, NSW, VIC, WA, SA and beyond. Whether you’re laying a new lawn, mulching garden beds, sizing irrigation, planning a water-wise garden, or working out green-waste bin loads, the calculators below give you fast, practical estimates so you can order the right amount the first time. Choose a category to get started.
Turf & Lawn Calculators
Everything you need to plan a new lawn, top up an existing one, or keep it healthy season to season.
Lawn Size & Turf Quantity Calculator
Lawn area and turf rolls needed, with a waste allowance.
Lawn Overseeding & Seed-Rate Calculator
The right seed quantity to thicken a patchy lawn.
Top-Dress Volume & Blend Calculator
Top-dressing soil or sand blend to level your lawn.
Soil, Mulch & Planting Calculators
Get your growing medium right — the foundation of every healthy Australian garden.
Soil & Underlay Volume Calculator
Soil or underlay volume for beds, turf base and fill.
pH Adjustment (Lime/Sulphur) Calculator
How much lime or sulphur to reach your target soil pH.
Native Plant Spacing Planner
Correct spacing for native shrubs and screens to thrive.
Water & Irrigation Calculators
Design a water-wise garden that survives Australian summers and water restrictions.
Sustainability & Outdoor Planning Calculators
Plan greener, cooler, lower-waste outdoor spaces.
Green Roof Load Calculator
Substrate depth and load weight within structural limits.
Green Waste Bin Capacity Calculator
How many bins your prunings and clippings will fill.
How to Use These Calculators Properly
- Measure in metres. All calculators use metric. Measure length and width in metres, or in centimetres divided by 100, for area and volume tools.
- Measure the real shape. For irregular beds, break the area into rectangles, calculate each, and add them together. For circles, measure the radius from centre to edge.
- Check your depth. Mulch, soil and top-dressing results depend heavily on depth — a bed at 75 mm needs far more material than one at 40 mm. Use the recommended depth for your purpose.
- Add a waste allowance. For turf and materials, order about 5–10% extra to cover cuts, curves and settling.
- These are estimates. Results are practical planning estimates based on typical Australian materials and conditions. Soil density, product brands, roof pitch and local climate vary, so treat outputs as a starting point and confirm with your supplier or a qualified professional for large or structural projects, especially green roofs and tank sizing.
Frequently Asked Questions
Yes. Every Garden Green calculator is completely free, with no sign-up required. Use them as often as you like.
Yes. They use metric measurements and are built around Australian climate zones, native species, soil types and water considerations, not overseas assumptions.
They give reliable planning estimates for ordering materials and sizing projects. Because soil density, product weights and site conditions vary, we recommend adding a small waste allowance and confirming with your supplier for large jobs.
Start with the Lawn Size and Turf Quantity Calculator to work out how much turf you need, then use the Soil and Underlay Volume Calculator for the base and the Irrigation Runtime Planner once it is laid.
Yes. Enter measurements in metres or centimetres. If you have imperial measurements, convert them first, as one foot is about 0.3 metres.
They are a good starting point, but for structural work like green roofs or large tanks, confirm the figures with a qualified professional.
