Engineering Calculators
29 curated mechanical, fluid, structural, automotive, HVAC and materials engineering tools. Electrical, Construction and Solar calculators stay in their own primary categories instead of being duplicated here.
Featured Engineering Calculators
A cross-discipline set of engineering-only tools, with no Electrical, Construction or Solar category duplicates.
Beam Deflection Calculator
Calculate elastic deflection for simply supported and cantilever beams under common loading cases.
Open toolPipe Pressure Drop Calculator
Calculate Darcy-Weisbach pressure loss with Reynolds number, friction factor and minor losses.
Open toolCooling Load Calculator
Estimate preliminary HVAC cooling load from envelope, ventilation, people, lighting and equipment gains.
Open toolEngine Displacement Calculator
Calculate engine CC, litres and cubic inches from bore, stroke and cylinder count.
Open toolMotor Current & Breaker Calculator
Calculate 1-phase or 3-phase motor current, starting current and a preliminary breaker rating.
Open toolSteel Column Calculator
Check axial stress, effective length, slenderness ratio and Euler buckling reference.
Open toolEngineering Formula Guides
Open the governing equation first, then use the worked examples and live calculator before moving to a deeper design tool.
Mechanical & Motor Engineering Calculators
8 toolsMotors, shafts, drives, gearing, belts, compressors and machine-performance checks.
Motor RPM Calculator
Find an AC motor's speed from its number of poles and supply frequency, including slip.
Open toolPulley Size & RPM Calculator
Find the driven pulley speed or the pulley size needed to reach a target RPM.
Open toolGear Ratio Calculator
Calculate gear ratio, output speed and torque for a gear pair or a gearbox.
Open toolBelt Length Calculator
Find the belt length needed between two pulleys from their diameters and centre distance.
Open toolAir Flow & Compressor CFM Calculator
Size an air compressor from tool demand and duty cycle, convert CFM to L/min or m³/h, and check tank runtime between PSI limits.
Open toolPressure Calculator & Converter
Convert between bar, psi, kPa and metres of water head — and see the pressure at the bottom of a tank.
Open toolFuel Consumption Calculator
Work out your vehicle's mileage, the fuel needed for a trip and what it will cost.
Open toolMotor Current & Breaker Calculator
Calculate 1-phase or 3-phase motor current, starting current and a preliminary breaker rating.
Open toolFluid & Hydraulic Engineering Calculators
7 toolsFlow, pumps, pipes, pressure loss, tanks, borewells and practical water-system sizing.
Water Pump HP Calculator
Find the pump horsepower needed to lift water to your tank from the flow rate, total height and pipe losses.
Open toolPump Flow Rate Calculator
Convert a pump's flow between litres per minute, litres per hour, m³/h and gallons, and see how long a tank takes to fill.
Open toolPipe Size Calculator
Choose the right pipe diameter for a given water flow so the velocity stays safe and pressure loss is low.
Open toolPipe Volume Calculator
Calculate how many litres of water a pipe holds and how long it takes to flush or fill it.
Open toolTank Filling Time Calculator
Calculate how long a water tank takes to fill from tank capacity, current water level and pump flow. You can also find the flow rate needed for a target filling time.
Open toolPipe Pressure Drop Calculator
Calculate Darcy-Weisbach pressure loss with Reynolds number, friction factor and minor losses.
Open toolPump Power Calculator
Calculate hydraulic, shaft and motor target power from flow, head, density and efficiency.
Open toolStructural Engineering Calculators
6 toolsBeam response, flexural stress, reactions, footing area and preliminary steel-member checks.
Beam Deflection Calculator
Calculate elastic deflection for simply supported and cantilever beams under common loading cases.
Open toolBending Stress Calculator
Calculate elastic flexural stress from bending moment, second moment of area and extreme-fibre distance.
Open toolShear Force & Bending Moment Calculator
Calculate support reaction, maximum shear and bending moment for common beam cases.
Open toolSpread Footing Size Calculator
Estimate preliminary footing plan area from service load and allowable soil bearing pressure.
Open toolSteel Beam Preliminary Sizing
Estimate required section modulus and second moment of area before selecting a steel section.
Open toolSteel Column Calculator
Check axial stress, effective length, slenderness ratio and Euler buckling reference.
Open toolAutomotive Engineering Calculators
4 toolsEngine geometry, displacement, compression ratio, horsepower, torque, bore and stroke relationships.
Engine Displacement Calculator
Calculate engine CC, litres and cubic inches from bore, stroke and cylinder count.
Open toolEngine Compression Ratio Calculator
Calculate compression ratio from swept volume and clearance volume.
Open toolHorsepower & Torque Calculator
Convert horsepower, torque and RPM using standard power relationships.
Open toolBore & Stroke Calculator
Solve bore, stroke and displacement relationships for reciprocating engines.
Open toolHVAC Engineering Calculators
2 toolsCooling-load estimation and airflow-based duct sizing for preliminary HVAC design checks.
Materials & Pavement Engineering Calculators
2 toolsMaterial-property and pavement quantity checks without duplicating the Construction calculator category.
Engineering Student Calculators Hub
Browse engineering formulas and practical tools by discipline from one student-focused launch page.
A Cleaner Engineering Calculator Structure
OneCalcApp now treats each calculator category as an owner instead of repeating the same tools across multiple hubs. This page concentrates on engineering-only mechanical, fluid, structural, automotive, HVAC and materials work. Electrical, Construction and Solar calculations remain discoverable from their dedicated categories, which keeps navigation clearer for users and search engines.
How to Use Engineering Calculators
- 1. Choose the discipline that matches the engineering question.
- 2. Open the calculator and confirm every input unit before calculating.
- 3. Review the formula, assumptions and limitations shown with the result.
- 4. Check safety-critical results against the applicable code, manufacturer data or a second method.
- 5. Use the result as a transparent study, estimating or preliminary-design record.