How to Check a Contractor’s Quote: 7 Checks You Can Do Yourself

Ask for a line-item BOQ, then run seven checks: M20 concrete takes about 8.07 bags of cement per m³; rebar weighs d² ÷ 162 kg per metre; a 9-inch wall takes 100 bricks per m²; wire is 1.5 mm² for lights, 2.5 mm² for sockets; water is 135 litres per person daily; cubes follow IS 456 Cl 15.2.2.

Start with the BOQ, not the rate

Ask for a line-item Bill of Quantities. It lists every material, its quantity, its rate and its IS specification. A rate such as "₹ per sq ft" gives you nothing to check, which is why per-sq-ft pricing hides contractor fraud. Once you have the BOQ, run these seven checks.

1. Concrete grade and cement quantity

The quote must state the grade for each pour. For M20 concrete, plan on about 8.07 bags of 50 kg cement per cubic metre (IS 456:2000). A 20 m³ slab needs roughly 161 bags, so a quote for 120 bags is a red flag. A variance above 10% needs a written explanation. The Concrete Mix Ratio Calculator scales this to your volume, and this guide walks through the cross-check.

2. Steel by weight

Rebar is billed by weight, so verify it by weight. The weight per metre of a bar is d² ÷ 162 kg, where d is the diameter in mm: a 12 mm bar weighs about 0.889 kg per metre. Weigh a sample and compare. The Bar Bending Schedule Calculator gives cutting lengths and weights for 13 bar shapes, and how to catch steel under-delivery covers the site checks.

3. Bricks per square metre

A 9-inch (230 mm) wall of standard 190 × 90 × 90 mm modular brick takes about 100 bricks per m², and a 4.5-inch (115 mm) partition about 50 (IS 1077:1992, IS 2212:1991). Deduct door and window openings from the wall area first, then allow 5–10% for wastage. The Brick Calculator does the arithmetic.

4. Wiring

Minimum copper sizes are 1.5 mm² for lighting and fans, 2.5 mm² for power sockets, 4 mm² for an AC or geyser, 6 mm² for a sub-panel feed and 10 mm² for the main incomer (IS 732:2019 Cl 6.2). The quote should also name the RCCB and MCB ratings. The Wire Size Calculator lists the typical MCB for each.

5. Water storage

Allow 135 litres per person per day on municipal supply and 150 on borewell (IS 1172:1993). A family of five on municipal water needs 675 litres a day; storing two-thirds of a day's demand gives 452 litres, so a 500 L tank. Use the Water Tank Size Calculator for your family.

6. Concrete testing

IS 456:2000 Cl 15.2.2 sets the minimum number of samples by volume: 1 for 1–5 m³, 2 for 6–15 m³, 3 for 16–30 m³ and 4 for 31–50 m³, and at least one sample from each shift. A 10 m³ pour needs 2 samples, which is 12 cubes at 6 cubes a sample. The Concrete Cube Test Calculator gives the count for any volume.

7. The payment bills

Running Account (RA) bills decide what you actually pay. Net payable is gross bill minus retention and advance recovery, plus GST, minus TDS. With 5% retention, 18% GST and 1% TDS on the value excluding GST, a ₹10,00,000 bill pays ₹11,20,000. The RA Bill Calculator shows each line.

Put it side by side

Run the numbers, then use the free Compare Contractor Quote tool to see which line items sit above IS-code quantities and typical rates. For unfamiliar words, see the glossary.