Ömer F. Durna6NGEN
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Engineering desk

Engineering calculators

36 tools in 8 categories. Results update as you type, with formulas and assumptions spelled out on each page. Share results as a link and star the ones you use most. Press Ctrl K anywhere to search.

Reference tables

Machine Elements

Bolts, shafts, keys, bearings, gears, belts, chains, springs, welds.

Bolt Tightening Torque

Preload and tightening torque for metric bolts, with a VDI 2230 equivalent-stress check.

FasteningVDI 2230ISO 898-1

Shaft Diameter

Minimum solid shaft diameter under combined bending and torsion (ASME shaft code), with a standard size.

ShaftTorsionASME

Parallel Key

DIN 6885 key size, hub bearing-pressure and key shear checks, and the minimum key length.

Shaft-hubDIN 6885Bearing pressure

Bearing Life

ISO 281 basic rating life L10 and reliability-adjusted life, in hours and years.

BearingISO 281L10

Gear Ratio

Spur gear pair: ratio, output speed and torque, pitch diameters and centre distance.

Power transmissionSpur gearModule

V-Belt Drive

Belt length, drive ratio, wrap angle on the small pulley and belt speed.

Power transmissionBeltISO 22

Chain Drive

Roller chain: number of links, actual centre distance, sprocket pitch diameters and chain speed.

Power transmissionChainISO 606

Power – Torque – Speed

The basis of every motor and shaft calculation: P = T·ω, in kW, hp and PS.

Power transmissionMotorUnits

Helical Compression Spring

Spring rate, deflection and Wahl-corrected shear stress.

SpringWahlEN 13906

Fillet Weld

Shear stress and resistance of a fillet weld — Eurocode 3 simplified method.

WeldingEN 1993-1-8Steel structures

Strength & Statics

Beams, sections, buckling, stress analysis, torsion, thermal stress.

Beam Deflection

Deflection, moment, shear and bending stress for simply supported and cantilever beams, with a section table.

StaticsEuler-BernoulliIPE / HEA / HEB

Section Properties

Area, second moment, section modulus, radius of gyration and mass per metre for rectangles, rounds, tubes, boxes and I-sections.

StaticsSecond momentProfiles

Column Buckling (Euler – Johnson)

Critical buckling load of a strut using Euler or Johnson by slenderness, plus the allowable load.

StabilityEulerSlenderness

Principal Stresses (Mohr)

Plane stress: principal stresses, maximum shear, principal angle, von Mises and Tresca equivalent stress.

StressMohr's circlevon Mises

Shaft Torsion

Torsional shear stress and angle of twist for solid and hollow shafts, with a twist-per-metre check.

ShaftTorsionStiffness

Thermal Expansion

Length change with temperature and the thermal stress in a fully restrained member.

ThermalExpansionStress

Fluids & Hydraulics

Pipe losses, pumps, hydraulic cylinders, pressure vessels.

Pipe Pressure Drop

Friction and minor losses in pipes with Darcy-Weisbach: velocity, Reynolds number and friction factor.

FluidsDarcy-WeisbachPiping

Pump Power

Hydraulic, shaft and electrical power from flow and head, with a standard motor size and annual energy.

FluidsPumpEnergy

Hydraulic Cylinder

Push and pull force from bore and rod size, and extend/retract speed from pump flow.

HydraulicsCylinderFlow

Pressure Vessel Wall Thickness

Required shell thickness and MAWP for a cylinder under internal pressure — ASME VIII Div. 1, UG-27.

Pressure vesselASME VIIIUG-27

Heat & Energy

Conduction, heating/cooling loads, insulation and U-values.

Heat Conduction

Fourier conduction through flat walls and cylinders: heat flux, heat flow and thermal resistance.

Heat transferFourierInsulation

Heating – Cooling Load

Q = ṁ·cp·ΔT: heat load from flow and temperature difference, or the flow needed for a given load.

HeatHVACProcess

Wall U-Value

Total thermal resistance, U-value and heat loss of a wall or roof with up to three layers.

InsulationTS 825Building

Electrical

Ohm's law, cable sizing, motor current, power factor correction.

Ohm's Law & Power

Enter any two of voltage, current, resistance and power — get the other two.

ElectricalOhmPower

Cable Voltage Drop

Single/three-phase line: current, % voltage drop, cable loss and the smallest standard size within the limit.

ElectricalCable sizingInstallation

Motor Current

Induction motor rated current, apparent and reactive power, and starting current for DOL and star-delta.

ElectricalMotorStarting

Power Factor Correction

Capacitor rating (kVAr) and capacitance per phase needed to raise the power factor.

Electricalcos φCapacitor

Manufacturing

Cutting parameters, sheet-metal bending, material weight.

Cutting Parameters

Spindle speed, feed rate, metal removal rate, cutting power and theoretical roughness for turning, milling and drilling.

MachiningCNCCutting speed

Sheet Metal Flat Pattern

Flat length of a bent sheet part: bend allowance, bend deduction and K-factor per DIN 6935.

Sheet metalDIN 6935K-factor

Material Weight

Weight of plate, round bar, tube, hollow section, angle and hex bar — steel, stainless, aluminium, copper…

WeightMaterialQuoting

Agricultural Machinery

Sprayer calibration, field work rate.

Sprayer Calibration

Application rate from nozzle flow, spacing and forward speed — or the nozzle flow needed for a target rate.

AgricultureSprayingCalibration

Field Work Rate

Theoretical and effective field capacity from working width and speed, total time and fuel per area.

AgricultureTractorPlanning

General & Maths

Calculator, unit converter, triangles, interpolation.

Scientific Calculator

Keyboard-friendly expression calculator with trigonometry, logarithms, powers, factorials and constants.

CalculatorTrigonometryKeyboard

Unit Converter

Length, force, pressure, torque, power, energy, flow, temperature… one value into every unit at once.

UnitsSIImperial

Triangle Solver

All sides, angles, area and perimeter from three sides, two sides and the included angle, or two angles and a side.

GeometryTrigonometryWorkshop

Linear Interpolation

Find intermediate values between table entries — steam tables, material catalogues, calibration curves.

MathsTablesInterpolation
GUIDESIn preparation

The engineering behind the tools

Articles explaining the theory of each tool with worked examples are being published one by one.

Vibration analysis

FFT-based vibration analysis for rotating machinery

Diagnosing bearing faults, unbalance and misalignment with the Fast Fourier Transform.

Coming soon
Power transmission

Calculating a V-belt drive from scratch

Section selection, ratio, centre distance, belt length and power capacity.

Coming soon · Related tool Statics

Beam deflection: theory, formulas and worked examples

Euler-Bernoulli for simply supported, cantilever and fixed beams.

Coming soon · Related tool
Manufacturing

GD&T basics for the practical engineer

Datums, form, orientation and position tolerances — what you actually need on the shop floor.

Coming soon
Materials

S235 or S355: when does it matter?

Yield strength, weldability, cost and when to specify which grade.

Coming soon
Thermodynamics

Heat transfer through composite walls: worked examples

Thermal resistance networks for flat and cylindrical walls, surface temperatures and U-values.

Coming soon · Related tool