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ConcreteCalc for Android — Help & Support

Contents

Getting Started

ConcreteCalc is a fast, reliable concrete volume calculator built for tradespeople, contractors, and DIYers. It works completely offline — no account needed, no internet required.

The app has three tabs at the bottom of the screen:

  • Calculator — Enter dimensions and get instant volume, bag counts, and truck loads.
  • Project — Save multiple calculations, see combined totals, and estimate costs.
  • Reference — Quick-reference tables for bag yields, common thicknesses, concrete strength, sonotube sizes, and more.

Using the Calculator

  1. Choose a shape from the scrollable row of icons at the top: Slab, Footing, Column, Wall, Steps, or Circle.
  2. Enter your dimensions. In imperial mode you enter feet, inches, and fractions. In metric mode you enter metres and centimetres.
  3. Pick a thickness (or depth/diameter depending on the shape) from the quick-select chips, or tap Custom to enter your own.
  4. Set a waste factor using the chips below the dimensions. The default is 7% — a good general-purpose value.
  5. View your results at the bottom of the screen: total volume, number of bags needed for each bag size, and truck loads required.
  6. Add to Project — tap the button below the results to save this calculation to your project for combined totals.
Tip: Tap outside the input field or press the back button to dismiss the keyboard and see your results.

Supported Shapes

ConcreteCalc handles the six most common concrete pour shapes:

  • Slab / Pad — Flat rectangular pours like patios, sidewalks, garage floors, and driveways. Enter length, width, and thickness.
  • Footing — Continuous strip footings for foundations and walls. Enter length, width, and depth.
  • Column (Sonotube) — Round columns and piers. Pick a diameter, enter height, and set the number of columns. Great for deck footings.
  • Wall — Poured concrete walls. Enter length, height, and wall thickness.
  • Steps / Stairs — Concrete steps with a landing platform. Enter width, number of steps, rise, run, and platform depth.
  • Circle — Circular slabs like fire pit pads and round patios. Enter diameter and thickness.

Waste Factor

The waste factor adds extra volume to your order to account for spillage, uneven subgrade, over-excavation, and form irregularities. Running short on a pour is expensive — always round up.

  • 0% — Exact volume only (not recommended for ordering).
  • 5% — Simple flat slabs with good, tight formwork.
  • 7% — Standard recommendation for most jobs.
  • 10% — Footings poured against earth, complex shapes, or uneven ground.
  • 15% — Pumped concrete, irregular pours, or when conditions are unpredictable.
  • Custom — Enter any percentage you need.
Pro tip: If this is your first time pouring on a particular site, err on the high side. A few extra bags or a small over-order on a truck is far cheaper than coming up short mid-pour and having to schedule a second delivery.

Settings & Customisation

Tap the gear icon in the top-right corner of the Calculator tab to open Settings.

Unit System

Switch between Imperial (feet, inches, cubic yards) and Metric (metres, centimetres, cubic metres). The app defaults to whatever measurement system is standard in your country.

Truck Capacity

Set the capacity of a standard ready-mix truck in your area. This is used to calculate how many truck loads you need. Common values:

  • 10 yd³ — Standard truck in the US and Canada.
  • 7.6 m³ — Standard truck in Australia, UK, and most metric countries.

Bag Sizes

Customise which bag sizes are available and their yields. The defaults are set based on your country — imperial countries get 40/60/80 lb bags, metric countries get 20/25/30/40 kg bags.

Reset to Defaults

Scroll to the bottom of Settings and tap Reset to Defaults to restore all settings to their original values for your region.

Setting Up Cost Estimates

ConcreteCalc can estimate the cost of your concrete order. Here is how to set it up:

  1. Go to the Project tab by tapping the second icon in the bottom navigation bar.
  2. You need at least one calculation saved. If the Project tab is empty, go back to the Calculator, run a calculation, and tap Add to Project.
  3. In the Project tab, tap Cost Settings to expand the pricing section.
  4. Enter the price per cubic yard (or per cubic metre in metric mode). This is the rate your local ready-mix supplier charges.
  5. Optionally enter a delivery fee. Many suppliers charge a flat delivery fee per truck.
  6. Your Estimated Cost appears immediately in the Project Total card above.
Note: Cost estimates are for planning purposes only. Actual prices depend on your supplier, mix design, delivery distance, and other factors. Always confirm pricing with your ready-mix supplier before ordering.

Project Tab & Totals

The Project tab lets you combine multiple calculations into a single job estimate:

  • Add calculations from the Calculator tab by tapping Add to Project below the results.
  • See combined totals — total volume, total truck loads, and estimated cost for the entire project.
  • Remove individual items by swiping left on a row.
  • Share a summary — tap Share Project Summary to generate a plain-text summary you can send to a supplier, client, or colleague via text, email, or any app.
  • Clear the project by tapping the trash icon in the top-right corner.

Your project is saved automatically and persists between app launches.

Reference Guide

The Reference tab gives you quick-access tables for common concrete data, so you do not have to look it up elsewhere:

  • Bag Yields — How much concrete each bag size produces.
  • Common Thicknesses — Recommended slab thickness for sidewalks, driveways, garages, and commercial work.
  • PSI / MPa Strength Guide — Which concrete strength to order for your application.
  • Sonotube Sizes — Which tube diameter to use for deck posts, footings, and structural piers.
  • Waste Factor Guide — Recommended waste percentages for different job types.
  • Ready-Mix Trucks — Common truck capacities and when to order ready-mix vs. use bags.

All reference data switches between imperial and metric to match your unit system setting.

Formulas & How Calculations Work

ConcreteCalc uses standard geometry formulas trusted across the construction industry. Here is exactly how every calculation works.

Slab / Pad

Volume = Length × Width × Thickness. Imperial inputs are converted so all measurements are in feet before multiplying. The result in cubic feet is divided by 27 to get cubic yards.

Footing

Volume = Length × Width × Depth. Identical to a slab — a rectangular solid.

Column (Sonotube)

Volume = π × (Diameter ÷ 2)² × Height × Quantity. The diameter in inches is divided by 24 to get the radius in feet.

Wall

Volume = Length × Height × Thickness.

Steps / Stairs

Steps Volume = Width × Run × Rise × N × (N + 1) ÷ 2. Platform Volume = Width × Platform Depth × (N × Rise). Total = Steps + Platform.

Circle (Round Slab)

Volume = π × (Diameter ÷ 2)² × Thickness.

Waste Factor

Adjusted Volume = Base Volume × (1 + Waste% ÷ 100).

Bags Needed

Bags = Volume ÷ Yield Per Bag, rounded up. Standard yields (imperial): 80 lb = 0.60 ft³, 60 lb = 0.45 ft³, 40 lb = 0.30 ft³.

Truck Loads

Truck Loads = Total Volume ÷ Truck Capacity, rounded up. Default: 10 yd³ (imperial) or 7.6 m³ (metric).

Frequently Asked Questions

How accurate are the calculations?

The formulas use standard geometry — the same maths your ready-mix supplier uses. The accuracy depends on how precisely you measure your site. Always use the waste factor to account for real-world conditions.

Should I use bags or order ready-mix?

As a general rule, bags are practical for jobs under 1 cubic yard (0.75 m³). Anything larger and ready-mix is faster, cheaper per unit, and produces a more consistent result.

What waste factor should I use?

7% is the standard recommendation for most jobs. Use 5% for simple flat slabs with tight formwork, 10% for footings poured against earth, and 15% for pumped concrete or irregular pours.

Can I change between metric and imperial?

Yes. Tap the gear icon on the Calculator tab to open Settings, then switch the Unit System toggle. The app defaults to the measurement system used in your country.

Is my data saved?

Yes. Your project, cost settings, and preferences are saved automatically on your device. They persist between app launches. We never send your data to any server.

Does the app work offline?

Yes, 100%. ConcreteCalc works entirely offline with no internet connection required. Use it on-site, in a basement, or anywhere you have your phone.

How do I share my project estimate?

In the Project tab, tap Share Project Summary. This generates a plain-text breakdown you can send via text, email, or any sharing method on your device.

The app is crashing or not working correctly

Make sure you are running the latest version of the app from Google Play. Try closing and reopening the app. If the problem persists, contact us at the email below with a description of the issue and your device model.

Contact Support

Cannot find the answer you need? Email us at support@top7systems.net and we will typically respond within 48 hours.

When reporting a bug, please include:

  • Your device model (e.g. Samsung Galaxy S24, Pixel 9)
  • Your Android version (found in Settings > About Phone)
  • A description of what happened and what you expected