Grout Quantity Calculator
Volume, weight, bags and water in one pass.
Inputs
Result
Formula
| Volume = L × W × T × over-pour | T in mm, divide by 1000 |
| Dry weight = volume × density | |
| Water = dry weight × water ratio | by weight, 1 kg ≈ 1 L |
| Bags = ceil(dry weight ÷ bag size) |
Machine base 1.2 × 0.8 m with 50 mm grout and 1.05 over-pour: 0.0504 m³, 110.9 kg of dry grout, so 5 bags of 25 kg (125 kg), 16.3 L of water, 3.25 L per bag.
FAQ
Why can't grout be watered like ordinary mortar?
Strength, expansion and flow are all designed around one fixed water ratio, working with plasticiser and expansive agent together. Extra water breaks it: strength drops about 8% per 1% of water; expansion becomes uncontrolled and the hardened grout shrinks, leaving voids under the base plate; and bleeding segregates the mix. Weigh the water.
What thickness should the grout layer be?
Machine base grouting is usually 50-100 mm, never less than 25 mm (thinner cannot be poured or levelled); sleeve grouting uses 15-20 mm cavities. Thickness also depends on anchor bolt embedment and shim height, and must allow the grout to flow under its own weight.
What about hot weather?
Heat accelerates setting: every 10 ℃ shortens working time by roughly half. Store dry grout and water in the shade, keep water below 20 ℃, mix small batches and place quickly. Never re-temper grout past its working time - the hydrated structure is already damaged and strength will drop sharply.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.