How to use it
- Enter the area in square metres.
- Enter the desired depth in millimetres.
- Click Calculate to see volume, weight and bags needed.
This calculator takes the area (m²) and depth (mm) you plan for a slate‑chipping project and instantly returns three practical figures:
- Volume in cubic metres – the raw space the chippings will fill.
- Weight in kilograms – useful for transport and cost estimates (using the standard density of 1500 kg / m³).
- Number of 25 kg bags – how many pre‑packed bags to order. Understanding each output helps you budget accurately, avoid ordering too little material, and plan delivery logistics without guesswork.
Pro tips
- Add 5‑10% extra volume for compaction and uneven ground.
- Round the bag count up to the next whole bag – you can’t buy a fraction of a bag.
- Order bags in bulk to reduce per‑bag shipping costs.
- Double‑check depth units; a common mistake is entering centimetres instead of millimetres.
Real-life examples
- A homeowner landscaping a 30 m² patio wants to know how many bags of slate chippings to order for a 50 mm depth.
- A contractor preparing a garden path needs the total weight to confirm lift capacity of the delivery truck.
- A DIY enthusiast estimating material costs for a backyard border of 12 m² at 30 mm depth.
Case study
Sarah entered her 25 m² garden area and a 40 mm depth; the calculator showed 1.0 m³, 1,500 kg and 60 bags. She ordered 62 bags, avoiding a shortfall and finishing her project on schedule.