What is CFT?
CFT stands for cubic feet — a unit of volume. One CFT is the space of a 1 ft × 1 ft × 1 ft cube, or about 0.0283 cubic metres. Most Chennai sand and aggregate suppliers quote price per CFT, per "unit" (which is 100 CFT) or per ton — so knowing how to convert between them saves you from being over-charged on the phone.
What is a "unit" of sand?
A unit is the trade-standard shorthand for 100 CFT. A unit of M-Sand is about 4.5 ton (washed and loose). A unit of blue metal is about 5.0-5.5 ton (heavier). When a supplier says "₹ 5,500 per unit", they mean 100 CFT — not 1 ton. Knowing the unit-to-ton ratio is the fastest way to compare two quotes.
Quick conversion table
| From | To | Multiplier |
|---|---|---|
| 1 unit | CFT | 100 CFT |
| 1 unit (M-Sand) | Ton | ~4.5 ton (washed) |
| 1 unit (Blue metal) | Ton | ~5.2 ton (crushed) |
| 1 ton (M-Sand) | CFT | ~23 CFT (varies by moisture) |
| 1 m³ | CFT | 35.3 CFT |
| 1 standard tipper | CFT | 300 CFT (≈ 13 ton M-Sand) |
| 1 standard tipper | Units | 3 units |
How to measure a lorry with a tape
Before the tipper tips, grab a 5-metre measuring tape and:
- Measure the inside length of the load body (in feet).
- Measure the inside width.
- Measure the average height of the pile above the body sides (tip it 3-4 places and average).
- Multiply L × W × H. That's the CFT.
A typical OneInfra 10-wheeler body is 14 ft long × 7 ft wide. A full 1.5 ft pile above the sides is 14 × 7 × 1.5 = 147 CFT above the body, plus the body's full volume — which together come to the standard 300 CFT mark. If your measurement gives you less, the tipper was short-loaded.
Worked example
You're quoted ₹ 5,500 per unit for double-washed M-Sand. The tipper arrives and you measure 12 ft × 7 ft × 1.2 ft of pile above the body = 100.8 CFT — that is 1 unit. So the load is 1 unit short of a full 3-unit tipper.
Now do the math the other way. You want 5 units of M-Sand. 5 units × 4.5 ton/unit = 22.5 ton. 22.5 ton ÷ 13 ton/tipper = ~1.7 tipper. Order 2 full tippers and accept the leftover, or split the load.
Common Chennai pitfalls
- "300 CFT" is the body capacity, not the loaded amount. A poorly-loaded 10-wheeler can carry 220 CFT and still look full. Always measure, don't eyeball.
- Wet sand weighs more. A monsoon-loaded tipper can come in at 16 ton for the same 300 CFT. This isn't a bargain — it just means more water weight, less actual sand.
- "Unit" varies by supplier. Some old-school suppliers still use "brass" or other local terms. Always confirm: 1 unit = 100 CFT = ~4.5 ton M-Sand.
- The sides aren't always square. Tippers with tapered or angled sides will throw off your L × W × H. Use the average of three measurements.
How much CFT do you need for a house?
Roughly, a 1,000 sq ft G+1 home needs about 2,300 CFT of material in total — split between M-Sand, P-Sand and aggregate. The exact breakdown depends on your design and mix ratio. Use the OneInfra quantity calculator to get a live estimate for your plot.
OneInfra tip: if you don't have a tape, ask the driver to roll the loaded tipper onto a weighbridge. We weigh every load at the Tambaram yard, and you can request a photo of the weighbridge slip on delivery.