Free calculators for real-world work

20 purpose-built tools for construction estimating, engineering, ad campaign maths, health metrics and home projects — each running published formulas, and each tested against a worked example.

Try concrete, ROAS, pipe, paint

Most used

Concrete CalculatorCubic yards, bag counts and cost for slabs, footings, columns and stairs.ConstructionGravel CalculatorCubic yards, tons and delivered cost for driveways and drainage.ConstructionBrick CalculatorBrick count, mortar bags and cost for walls, beds and patios.ConstructionPipe Diameter CalculatorMinimum internal diameter from flow rate and target velocity.EngineeringCPM CalculatorCPM, impressions from budget, and spend needed for a reach target.MarketingROAS CalculatorROAS, break-even ROAS from margin, and real profit after ad spend.MarketingA1C CalculatorA1C to eAG in mg/dL and mmol/L, with interpretation ranges.HealthPaint CalculatorNewGallons or litres for walls and ceiling, after doors, windows and coats.Home Services

Construction

Material estimation calculators for concrete, masonry, aggregates and paving work.

Asphalt CalculatorCompacted volume, tonnage and truckloads for paving and overlays.Bitumen CalculatorLitres, tonnes and drum count for tack coats, prime coats and sealing.Brick CalculatorBrick count, mortar bags and cost for walls, beds and patios.Cement CalculatorBags of cement for concrete, mortar, plaster and screed by mix ratio.Concrete CalculatorCubic yards, bag counts and cost for slabs, footings, columns and stairs.Gravel CalculatorCubic yards, tons and delivered cost for driveways and drainage.Sand CalculatorYards, tons and bags for paver bases, patios and sandboxes.Topsoil CalculatorYards, tons and bag count for lawns, gardens and raised beds.

Engineering

Technical calculators for mechanical systems, fluid dynamics and industrial equipment sizing.

Boiler Feed Pump CalculatorFlow, TDH, shaft power and motor size from boiler capacity.Pipe Diameter CalculatorMinimum internal diameter from flow rate and target velocity.Pressure Drop CalculatorHazen-Williams head loss with a full C-factor reference table.Pump Flow Rate CalculatorFlow from volume ÷ time or from pipe diameter × velocity.

Marketing

Digital advertising calculators for budgeting, CPM, impressions and campaign planning.

Conversion Rate CalculatorCVR, forecast conversions, and traffic required for a goal.CPC CalculatorSolve CPC, click volume or budget from any two known values.CPM CalculatorCPM, impressions from budget, and spend needed for a reach target.ROAS CalculatorROAS, break-even ROAS from margin, and real profit after ad spend.

Health

Medical and wellness calculators for tracking health metrics and understanding lab results.

A1C CalculatorA1C to eAG in mg/dL and mmol/L, with interpretation ranges.

Home Services

Cost and quantity estimators for home improvement, painting, landscaping and contractor work.

Mulch CalculatorNewCubic yards and bag count for beds and tree rings, with bulk vs bag cost.Paint CalculatorNewGallons or litres for walls and ceiling, after doors, windows and coats.Tree Removal Cost CalculatorPrice range by tree size and access, plus stump and haul-away add-ons.

Built to be checked, not just used

Behind each tool sits a named standard or published reference — ACI mix yields, Hazen-Williams C-factors, NGSP-aligned A1C conversion, IAB advertising metric definitions — and a worked example the maths is regression-tested against. Results round only at the output step, currency is computed in whole cents, and every page states its rounding rule so an estimate can be traced back by hand.

Formulas shown
Every page lists the equations it runs.
Worked examples
Each tool is tested against one before release.
Imperial and metric
Switching units converts your numbers.

Guides

All guides
How to Estimate Concrete for Any ProjectThe volume method, wastage allowances and the ready-mix-versus-bags decision, from first principles.8 min readReady-Mix vs Bagged Concrete: A Cost BreakdownThe true break-even, the fees nobody quotes, and why structural pours change the maths.7 min readDriveway Materials Compared: Gravel, Asphalt and ConcreteCost, lifespan, maintenance and climate compared across three materials — plus how to estimate each.9 min readPump Sizing Basics: Flow, Head and Motor PowerFlow, head, pipe diameter and motor power — the sizing chain in the order engineers work it.9 min read