concrete-calculator

Lightweight, zero-dependency concrete volume, bag, and cost calculator for JavaScript and TypeScript.

Calculate how much concrete you need for slabs, cylinders, footings, stairs, curbs, and more — in cubic feet, cubic yards, or number of bags.

Built by SlabCalc.co — free online concrete calculators for contractors, DIYers, and engineers.

Install

npm install concrete-calculator

Quick Start

import { estimate } from 'concrete-calculator';

// 10 × 12 ft slab, 4 inches thick
const result = estimate(
  { length: 10, width: 12, thickness: 4 / 12 },
  { wasteFactor: 1.1 }  // 10% waste allowance
);

console.log(result);
// {
//   cubicFeet: 44,
//   cubicYards: 1.63,
//   bags: 74,           (80 lb bags)
//   bagCost: 481,       (at $6.50/bag)
//   readyMixCost: 244.44  (at $150/yard)
// }

Shapes

All shape functions accept dimensions in any consistent unit and return volume in that unit cubed.

import { slab, cylinder, footing, stairs, curb, hollowCylinder } from 'concrete-calculator';

// Rectangular slab: length × width × thickness
slab(20, 10, 0.33);  // 66 cu ft

// Cylinder / sonotube: diameter, height
cylinder(2, 4);  // 12.57 cu ft

// Continuous footing: length × width × depth
footing(40, 1.5, 1);  // 60 cu ft

// Staircase: risePerStep, runPerStep, width, numberOfSteps
stairs(7/12, 11/12, 3, 5);  // solid volume for 5 steps

// Curb: length × width × height
curb(100, 0.5, 0.5);  // 25 cu ft

// Hollow cylinder: outerDiameter, innerDiameter, height
hollowCylinder(4, 3, 5);  // ring volume

Need an interactive version? Try the Concrete Slab Calculator or the Concrete Column Calculator at SlabCalc.co.

Unit Conversions

import { cubicFeetToYards, cubicYardsToCubicFeet, cubicFeetToMeters, cubicMetersToYards } from 'concrete-calculator';

cubicFeetToYards(54);    // 2
cubicYardsToCubicFeet(2); // 54
cubicFeetToMeters(35.31); // ≈ 1
cubicMetersToYards(1);    // ≈ 1.31

Bag Estimation

Estimate pre-mixed concrete bags (Quikrete, Sakrete, etc.) needed for your project.

import { bagEstimate, bagsFromYards } from 'concrete-calculator';

// 50 cu ft with 80 lb bags
bagEstimate(50, 80);  // 84 bags

// 1 cubic yard with 60 lb bags
bagsFromYards(1, 60);  // 60 bags

// Supported bag sizes: 40, 50, 60, 80 (lbs)

Learn more about how many bags of concrete you need on SlabCalc.co.

Cost Estimation

import { readyMixCost, bagCost } from 'concrete-calculator';

// Ready-mix truck delivery
readyMixCost(3, 150);  // { yards: 3, cost: 450, shortLoad: false }

// With short-load fee ($100 under 1 yard)
readyMixCost(0.5, 150, 100, 1);  // { yards: 0.5, cost: 175, shortLoad: true }

// Bagged concrete cost
bagCost(50, 80, 6.50);  // { bags: 84, cost: 546 }

See the full Concrete Cost Calculator for a detailed breakdown including delivery fees, labor, and rebar.

All-in-One Estimate

The estimate() function gives you everything at once for a rectangular slab:

import { estimate } from 'concrete-calculator';

const result = estimate(
  { length: 20, width: 10, thickness: 6 / 12 },
  {
    wasteFactor: 1.1,      // 10% extra (default)
    bagSize: 80,           // 80 lb bags (default)
    pricePerBag: 6.50,     // per bag (default)
    pricePerYard: 150,     // ready-mix price (default)
  }
);

For more complex projects, use the interactive Concrete Slab Calculator at SlabCalc.co — it handles rebar spacing, sub-base depth, and generates full material lists.

TypeScript

Full type definitions are included out of the box.

import { estimate, slab, bagEstimate } from 'concrete-calculator';
// All functions are fully typed — no @types package needed.

Common Concrete Projects

Project	Calculator
Patio or driveway slab	Slab Calculator
Deck or fence post footings	Footing Calculator
Round columns / sonotubes	Column Calculator
Steps and stairs	Stairs Calculator
Retaining walls	Wall Calculator
Curbs and gutters	Curb Calculator

License

MIT — see LICENSE.

SlabCalc.co — Free concrete calculators, guides, and cost estimators for your next project.