# Concrete Mix Ratio Calculator

> Converts a wet concrete volume into the dry materials for a nominal volumetric mix: the dry volume (× 1.54 for voids and shrinkage) is split by the cement : sand : aggregate parts, converted to mass with bulk densities (cement 1,440, sand 1,600, aggregate 1,450 kg/m³), cement is expressed in bags and water follows the water-cement ratio.

- Calculator id: `concrete-mix-ratio` · Category: Construction & Home (`construction`) · Tool name: `calculate_concrete_mix_quantities`
- Canonical page: https://tttkmbb.com/construction/concrete-mix-ratio · This document: https://tttkmbb.com/construction/concrete-mix-ratio.md · JSON definition: https://tttkmbb.com/construction/concrete-mix-ratio.json

## Purpose

Converts a wet concrete volume into the dry materials for a nominal volumetric mix: the dry volume (× 1.54 for voids and shrinkage) is split by the cement : sand : aggregate parts, converted to mass with bulk densities (cement 1,440, sand 1,600, aggregate 1,450 kg/m³), cement is expressed in bags and water follows the water-cement ratio.

**Use when:** You are site-mixing concrete by volume batching and need the cement bags, sand, coarse aggregate and water for a given volume at a nominal mix such as 1:2:4 (M15) or 1:1.5:3 (M20).

**Do not use when:** You are ordering ready-mix or bagged premix (use concrete-slab or concrete-footing for volumes and bags), or you need a designed mix for a specified strength with admixtures (a design mix from the supplier's laboratory).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `wet_concrete_volume_m3` | number | m³ | required | Volume of placed (compacted) concrete in cubic metres, waste included. (> 0, max 10000) |
| `mix_ratio` | enum: 1_3_6 \| 1_2_4 \| 1_1_5_3 \| 1_1_2 \| custom |  | optional, default "1_2_4" | Nominal cement : sand : coarse-aggregate proportions by volume, with the approximate IS 456 grade they correspond to. |
| `cement_parts` | number |  | optional | Cement parts by volume for mix_ratio = custom (usually 1). (> 0, max 10) |
| `sand_parts` | number |  | optional | Fine-aggregate (sand) parts by volume for mix_ratio = custom. (min 0, max 20) |
| `aggregate_parts` | number |  | optional | Coarse-aggregate parts by volume for mix_ratio = custom. (min 0, max 20) |
| `dry_volume_factor` | number |  | optional, default 1.54 | Ratio of loose dry materials to compacted wet concrete; 1.52–1.57 is the usual allowance, 1.54 is the common estimating value. (min 1, max 2) |
| `cement_density_kg_m3` | number | kg/m³ | optional, default 1440 | Loose bulk density of cement (1,440 kg/m³, i.e. one 50 kg bag ≈ 0.0347 m³ ≈ 1.226 ft³). (> 0, max 3000) |
| `bag_kg` | number | kg | optional, default 50 | Mass of one cement bag: 50 kg (India, most of the world), 25 kg (UK/EU), 40 kg (Australia), 42.6 kg (US 94 lb bag). (> 0, max 100) |
| `water_cement_ratio` | number |  | optional, default 0.5 | Mass of water per mass of cement; 0.45–0.55 is typical for nominal mixes (lower gives higher strength but stiffer concrete). (min 0.3, max 1) |
| `sand_density_kg_m3` | number | kg/m³ | optional, default 1600 | Loose bulk density of dry sand. (> 0, max 3000) |
| `aggregate_density_kg_m3` | number | kg/m³ | optional, default 1450 | Loose bulk density of coarse aggregate (20 mm crushed stone ≈ 1,450 kg/m³). (> 0, max 3000) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `mix_ratio_used` | string |  | Cement : sand : aggregate parts applied. |
| `dry_volume_m3` | number | m³ | wet_concrete_volume × dry_volume_factor. |
| `cement_m3` | number | m³ | dry_volume × cement_parts / total_parts. |
| `cement_kg` | number | kg | cement_m3 × cement_density. |
| `cement_bags` | integer |  | ceil(cement_kg / bag_kg). |
| `sand_m3` | number | m³ | dry_volume × sand_parts / total_parts. |
| `sand_kg` | number | kg | sand_m3 × sand_density. |
| `aggregate_m3` | number | m³ | dry_volume × aggregate_parts / total_parts. |
| `aggregate_kg` | number | kg | aggregate_m3 × aggregate_density. |
| `water_liters` | number | L | water_cement_ratio × cement_kg (1 kg of water = 1 L). |

## Formula

`dry_volume = wet_concrete_volume_m3 × dry_volume_factor; total_parts = cement + sand + aggregate; cement_m3 = dry_volume × cement_parts / total_parts (sand and aggregate likewise); cement_kg = cement_m3 × 1440; cement_bags = ceil(cement_kg / bag_kg); sand_kg = sand_m3 × 1600; aggregate_kg = aggregate_m3 × 1450; water_L = water_cement_ratio × cement_kg.`

Volume-batching (nominal mix) method used for small site-mixed pours; the 1.54 factor and the bulk densities are estimating conventions, and nominal mixes correspond only approximately to the IS 456 grades (M10–M25). Aggregate moisture, bulking of damp sand and wastage are not included; add 3–5 %.

## Data Sources

- Wikipedia – Concrete (mix design) — https://en.wikipedia.org/wiki/Concrete (reference, retrieved 2026-09-24)
- Wikipedia – Types of concrete — https://en.wikipedia.org/wiki/Types_of_concrete (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/concrete-mix-ratio?wet_concrete_volume_m3=…`
- `POST https://tttkmbb.com/api/v1/calculate/concrete-mix-ratio` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/concrete-mix-ratio · OpenAPI operationId `calculate_concrete_mix_quantities` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "concrete-mix-ratio", "inputs": {…}}`

## Example

- 1 m³ at 1:2:4, 50 kg bags, w/c 0.5: inputs `{"wet_concrete_volume_m3":1,"mix_ratio":"1_2_4","dry_volume_factor":1.54,"cement_density_kg_m3":1440,"bag_kg":50,"water_cement_ratio":0.5}` → `{"dry_volume_m3":1.54,"cement_m3":0.22,"cement_kg":316.8,"cement_bags":7,"sand_m3":0.44,"sand_kg":704,"aggregate_m3":0.88,"aggregate_kg":1276,"water_liters":158.4,"mix_ratio_used":"1 : 2 : 4"}`
- 2.5 m³ at 1:1.5:3 (M20), 25 kg bags, w/c 0.45: inputs `{"wet_concrete_volume_m3":2.5,"mix_ratio":"1_1_5_3","bag_kg":25,"water_cement_ratio":0.45}` → `{"dry_volume_m3":3.85,"cement_m3":0.7,"cement_kg":1008,"cement_bags":41,"sand_m3":1.05,"sand_kg":1680,"aggregate_m3":2.1,"aggregate_kg":3045,"water_liters":453.6}`

```
GET https://tttkmbb.com/api/v1/calculate/concrete-mix-ratio?wet_concrete_volume_m3=1&mix_ratio=1_2_4&dry_volume_factor=1.54&cement_density_kg_m3=1440&bag_kg=50&water_cement_ratio=0.5
```

## Limitations

You are ordering ready-mix or bagged premix (use concrete-slab or concrete-footing for volumes and bags), or you need a designed mix for a specified strength with admixtures (a design mix from the supplier's laboratory). Volume-batching (nominal mix) method used for small site-mixed pours; the 1.54 factor and the bulk densities are estimating conventions, and nominal mixes correspond only approximately to the IS 456 grades (M10–M25). Aggregate moisture, bulking of damp sand and wastage are not included; add 3–5 %. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Why multiply by 1.54?**

Loose cement, sand and stone contain voids that are filled when the mix is compacted, so about 1.54 m³ of dry materials produce 1 m³ of concrete; some references use 1.52–1.57.

**How many cement bags per cubic metre?**

About 6.3 bags of 50 kg (317 kg) for 1:2:4 and 8 bags (403 kg) for 1:1.5:3; bags are rounded up.

**Is 1:2:4 the same as M15?**

Approximately: IS 456 lists 1:2:4 as the nominal mix for M15 and 1:1.5:3 for M20, but the actual strength depends on the water-cement ratio, aggregate and curing, so a design mix is needed where a specific strength must be guaranteed.

## Related

- [Concrete Slab Calculator](https://tttkmbb.com/construction/concrete-slab.md) — Wet volume of a slab to feed into this calculator.
- [Concrete Footing Calculator](https://tttkmbb.com/construction/concrete-footing.md) — Wet volume of footings and piers.
- [Gravel Calculator](https://tttkmbb.com/construction/gravel.md) — Aggregate weight and volume conversions.