46 free tools · no sign-up
Transparent Engineering Calculators & Solvers
Mechanical, electrical, civil and unit conversion calculators for students, technicians and engineers — every result comes with the formula and step-by-step solution.
46 calculators
MechanicalTorque, power, stress, flow and energy
- Torque CalculatorTorque from force and lever arm distance.T = F × r
- Power CalculatorShaft power from torque and rotational speed.P = 2π × N × T / 60
- Rotational Power CalculatorMechanical rotational power from torque and angular velocity.P = T × ω
- RPM CalculatorRotational speed from power and torque.N = 60 × P / (2π × T)
- Gear Ratio CalculatorGear ratio and output speed from tooth counts.i = Z₂ / Z₁, N₂ = N₁ / i
- Mechanical Efficiency CalculatorEfficiency from output and input power.η = P_out / P_in × 100 %
- Force CalculatorNewton's second law: force from mass and acceleration.F = m × a
- Pressure CalculatorPressure from force and area.P = F / A
- Stress CalculatorNormal stress from axial load and cross-section.σ = F / A
- Strain CalculatorEngineering strain from change in length.ε = ΔL / L₀
- Flow Rate CalculatorVolumetric flow from area and velocity.Q = A × v
- Velocity CalculatorAverage velocity from distance and time.v = d / t
- Work and Energy CalculatorWork done by a constant force over a distance.W = F × d
- Thermal Efficiency CalculatorCarnot (maximum) efficiency between two temperatures.η = 1 − T_c / T_h
- Horsepower ↔ kW ConverterConvert between common horsepower units.Unit conversion
ElectricalOhm's law, power, phases and energy use
- Ohm's Law CalculatorEnter any two of voltage, current, resistance.V = I × R
- Electrical Power CalculatorDC power from voltage and current.P = V × I
- Voltage CalculatorVoltage from current and resistance.V = I × R
- Current CalculatorCurrent from voltage and resistance.I = V / R
- Resistance CalculatorResistance from voltage and current.R = V / I
- Energy Consumption CalculatorkWh usage and cost of an appliance.E = P × h × days, Cost = E(kWh) × tariff
- Single-Phase Power CalculatorAC real, apparent and reactive power (1-phase).P = V × I × PF
- Three-Phase Power CalculatorBalanced 3-phase power from line voltage and current.P = √3 × V_L × I_L × PF
- Electrical Efficiency CalculatorEfficiency of a motor, transformer or supply.η = P_out / P_in × 100 %
- kW ↔ HP ConverterConvert between common kw units.Unit conversion
CivilConcrete, bricks, steel and earthwork
- Geometric Area CalculatorArea of rectangles, circles, triangles and trapezoids.Rectangle: A = L × W · Circle: A = πr² · Triangle: A = ½bh · Trapezoid: A = ½(a + b)h
- Geometric Volume CalculatorVolume of solid or hollow cuboids, cylinders, spheres and cones.Solid cuboid: V = L × W × H · Hollow cuboid: V = LₒWₒHₒ − LᵢWᵢHᵢ · Cylinder: V = πr²h · Hollow cylinder: V = πh(R² − r²) · Sphere: V = ⁴⁄₃πr³ · Hollow sphere: V = ⁴⁄₃π(R³ − r³) · Solid cone: V = ⅓πr²h · Hollow cone: V = ⅓πh(R² − r²)
- Concrete Volume CalculatorConcrete for a slab, including wastage.V = L × W × T × (1 + waste %)
- Brick Quantity CalculatorNumber of bricks for a wall.N = V_wall / V_brick+mortar × (1 + waste %)
- Cement/Sand/Aggregate CalculatorMaterial quantities for a nominal concrete mix.V_dry = V_wet × 1.54; part = V_dry × ratio / Σratio
- Weight of Steel CalculatorWeight of round reinforcement bars.W = D² / 162 × L × n
- Pipe Volume CalculatorInternal volume (capacity) of a pipe.V = π × d² / 4 × L
- Excavation Volume CalculatorBank and loose volume of a rectangular pit.V_bank = L × W × D, V_loose = V_bank × (1 + swell %)
- Unit Weight CalculatorUnit weight (specific weight) from mass and volume.γ = m × g / V
GeneralUnit converters for every quantity
- Density CalculatorDensity from mass and volume.ρ = m / V
- Unit ConverterConvert any engineering quantity between units.Unit conversion
- Length ConverterConvert between common length units.Unit conversion
- Area ConverterConvert between common area units.Unit conversion
- Volume ConverterConvert between common volume units.Unit conversion
- Mass ConverterConvert between common mass units.Unit conversion
- Pressure ConverterConvert between common pressure units.Unit conversion
- Temperature ConverterConvert between common temperature units.Unit conversion
- Force ConverterConvert between common force units.Unit conversion
- Energy ConverterConvert between common energy units.Unit conversion
- Power ConverterConvert between common power units.Unit conversion
- Speed ConverterConvert between common speed units.Unit conversion
Engineering calculations you can check
Engineering Calculator Hub brings 46 free mechanical, electrical, civil and unit conversion tools into one searchable library. Each calculator is designed to make the method visible with clear units, formulas and step-by-step solutions, helping students, technicians, engineers and educators verify everyday calculations.
Frequently asked questions
Are these engineering calculators free to use?
Yes. All 46 calculators and converters are free to use, with no account or sign-up required.
Which engineering subjects are covered?
The collection covers mechanical, electrical and civil engineering, plus common unit conversions for engineering work.
Do the calculators show formulas and working?
Yes. Formula calculators identify the equation used and show a step-by-step solution so you can review the method behind the result.
Can I enter values in different units?
Yes. Supported inputs include practical metric and imperial units, and results can be displayed in appropriate alternative units.