RCC Slab Concrete Calculator Nepal: Volume, Cement Bags & Mix

RCC slab concrete is the pour homeowners remember: one day of mixer noise, a pile of bags, and a roof that has to last decades. Searches for slab dhalai, chhat concrete and how much cement for a slab usually mean one thing—how many bags, how much sand and aggregate, and whether the contractor’s “about 80 bags” is even close.

Use the free RCC slab concrete calculator to turn length, width, thickness and mix into wet volume, bags and a planning cost. Tighten the mix with the concrete material calculator, count steel with the rebar weight tool, and hire shuttering with the formwork calculator. Whole-house bag context: how much cement for a house.

The volume formula (then the mix)

1. 1Convert plan size to metres. 1 foot = 0.3048 m; 1,000 sq. ft. ≈ 92.9 m².
2. 2Wet volume = length × width × thickness. Deduct large stair voids only if they are not poured with the slab.
3. 3Add 2–5% wastage for mixer leftover, pump line and level correction. Monsoon pours trend higher.
4. 4Split wet volume into cement : sand : aggregate from the nominal mix (1:1½:3, 1:2:4) or from the mix design.
5. 5Cement bags = cement volume × 1440 kg/m³ ÷ 50. Sand and aggregate are ordered in m³ or tractor loads, not bags.

Worked example: 10 m × 8 m × 0.125 m roof slab → 10 m³ wet. Plus 5% wastage → 10.5 m³. At 1:1.5:3 (M20-ish nominal), cement is about 1/5.5 of the dry volume after the usual 54% dry-volume uplift. The slab calculator does this arithmetic with editable Nepal rates so you can replace defaults with today’s cement price and sand–aggregate rates.

What the calculator does not replace

• Beam and drop volume — measure the beam schedule; do not hide it inside “slab thickness.”
• Steel — a 125 mm residential slab is often 8–12 kg/m² of bar depending on spans; use the steel rebar guide.
• Formwork — soffit area plus beam sides. See formwork & shuttering.
• Curing — 7–14 days of water is cheaper than a cracked slab. Budget labour and a hose, not just bags.
• Pour sequence — one floor at a time; leftover bags from last month’s pour do not survive monsoon storage.

Typical Nepal residential thicknesses

• 100 mm — light rooms, short spans, only if the engineer allows it.
• 125 mm — the common Kathmandu-valley house floor/roof starting point.
• 150 mm — longer spans, parking slabs, or heavier finishes.
• Waist slab / staircase — thinner on plan but steeper; measure actual surface, not floor area.

Order materials for this pour, not for the whole house. Cement ages. Aggregate piles get stolen. The slab calculator is a purchase ceiling for Tuesday’s dhalai.— GharNaksa site practice

From estimate to a tracked pour

1. 1Run the RCC slab calculator with drawing sizes.
2. 2Cross-check bags against the cement purchase cost tool.
3. 3Get two supplier quotes for the same mix and bag type (PPC vs OPC—see PPC vs OPC).
4. 4Log accepted bags, tractor loads and leftover in GharNaksa against that floor so the next slab starts from stock, not WhatsApp guesses.