THE WHOLE-ORDER COMPARISON
Bags or bulk?
Compare what you must buy.
A bag price and a bulk price describe different purchases. A fair comparison includes the amount you have to buy and the cost of getting it to your garden.
Start with the layer you need
A 200 cm × 100 cm bed topped up by 5 cm needs 100 litres before any extra allowance. Filling the same space 30 cm deep needs 600 litres. Measure the empty layer, rather than automatically using the full height of the bed. If a container has sloping sides, a straight-sided estimate will not precisely describe it.
Convert centimetres to metres before multiplying. For a 2 m × 1 m × 0.05 m layer, the volume is 0.1 m³. Multiply by 1,000 to get litres.
Round the purchases, not just the space
For a 320-litre space, 25-litre bags require 320 ÷ 25 = 12.8 bags. You must buy 13 whole bags, providing 325 litres. A bulk supplier with a 0.5 m³ minimum charges for at least 500 litres even though the space needs less.
A minimum and an increment are different conditions. A minimum sets the smallest charged order. An increment sets the size of the steps you can buy. If you need 0.6 m³ and the supplier sells in 0.25 m³ increments, you need a 0.75 m³ order. Confirm how your supplier applies both conditions.
A worked price comparison
The following prices are invented examples, not retailer quotes. Both options are assumed to describe equivalent material and use the same tax basis. No extra allowance is included.
| 320 litres needed | Bagged | Bulk |
|---|---|---|
| Charged quantity | 13 × 25 L = 325 L | 0.5 m³ minimum = 500 L |
| Example unit price | A$7 per bag | A$90 per m³ |
| Material cost | A$91 | A$45 |
| Example transport cost | A$0 | A$35 |
| Total | A$91 | A$80 |
Bulk costs A$11 less in this example. If the delivery charge becomes A$60, the bulk total becomes A$105 and bags cost A$14 less. Delivery can change the result even when bulk has a lower material price.
Compare your own quotes ↗Read the quote before ordering
- Use the actual labelled bag volume, not a guessed standard size.
- Check that the materials are comparable in composition and suitability.
- Include delivery, transport charges and the same tax basis for both options.
- Ask about minimum charges and purchasing increments. Conditions differ among suppliers.
- Check space for unloading and storage. The calculator does not estimate lifting requirements or vehicle weight limits.
Centenary Landscaping explains cubic-metre estimates and bag equivalents. A Gunalda Landscape Supplies price list provides an example of a minimum bulk charge; it is not used for current price defaults.