Mechanical, electrical, structural, fluid, thermal, and fabrication calculators in one place: stress and strain, beam deflection, Reynolds number, pipe flow, bolt torque, weld sizing, corrosion rate, and well over a hundred more.
Each tool runs free in your browser, shows the governing formula with a worked example, and links to the related calculators an engineer reaches for next. Browse by discipline below or search by name.
📐 Mechanical Engineering 19
Bearing Stress CalculatorBearing stress for bolts, pins and rivets, with projected area, safety factor and pass/fail.Bolt Load CalculatorFind how much tension, shear or combined load a bolt — or a group of bolts — can actually carry, with allowable capacity, a clear pass / fail...Bolt Torque CalculatorFind the tightening torque for a bolt from its size, grade, thread and lubrication — using T = K × F × D — with the resulting clamp...Factor of Safety CalculatorThe safety margin between a material’s strength and the applied stress.Gear Ratio CalculatorGear ratio from tooth counts, with output speed, torque, and compound-train staging.Mechanical Force CalculatorForce from acceleration, weight, pressure, torque, friction, centripetal motion, springs or impact.Mechanical Stress CalculatorAxial, bending, shear, bearing and torsional stress, with a safety factor and yield check.Moment of Inertia CalculatorArea and mass moment of inertia for common shapes.Pressure Vessel (Hoop Stress) CalculatorHoop and longitudinal stress in a thin-wall cylinder or sphere, checked against allowable, with min thickness.Pulley & Belt Length CalculatorBelt length for a two-pulley drive, with speed ratio, output RPM, belt speed and wrap angles.Section Modulus CalculatorSection modulus, moment of inertia and bending capacity for beams, rounds, tubes and I-beams.Shaft Diameter CalculatorMinimum shaft diameter for combined torque and bending by the ASME method, from torque or power and speed.Shear Stress CalculatorShear stress in a pin, bolt, punched hole or beam, with a material-strength and safety-factor pass/fail check. Single or double shear, three section types.Spring Rate CalculatorFind helical spring rate from wire size, coil diameter and turns (k = Gd4/8D3N), or from measured load and travel. Spring index and Wahl shear-stress check.Strain CalculatorCalculate normal, thermal, lateral (Poisson) and shear strain, with microstrain and true-strain output. Metric and imperial.Torque CalculatorTorque from a force and lever arm, a motor’s power and speed, or a bolt spec.Weld Size CalculatorFind the right weld size for the job. Enter the plate thickness and the load, and get the required fillet leg, the effective throat, the code minimum and...Weld Strength CalculatorEnter a weld you already have — size, length and electrode — and find out how much load it can actually carry, with a clear pass / fail...Young’s Modulus CalculatorFind Young's modulus from a tension test and identify the material, or predict how far a part stretches under load. Hooke's law, metric and imperial.
📐 Fluid Mechanics 11
Bernoulli Equation CalculatorFind the pressure at a second point of a pipe, or the flow rate from a pressure drop (venturi), using Bernoulli with continuity and head loss.Drag Force CalculatorAerodynamic and hydrodynamic drag force F = half rho v-squared Cd A, with dynamic pressure and power to overcome.Friction Factor CalculatorDarcy and Fanning friction factor from Reynolds number and roughness, solved with Colebrook.Hydraulic Diameter CalculatorHydraulic diameter D_h = 4A/P for ducts, annuli and channels, to apply round-pipe flow formulas.Open-Channel Flow CalculatorOpen-channel flow by the Manning equation for trapezoidal, rectangular and triangular sections, with velocity.Orifice Flow CalculatorLiquid flow through an orifice or nozzle from pressure or head (Q = Cd A sqrt(2 dP/rho)), with discharge coefficients.Pipe Flow CalculatorFlow, velocity, pressure drop and pump power for a pipe, in one tool.Pressure Drop CalculatorPressure drop and pump head for fluid in a pipe - Darcy-Weisbach with automatic friction factor.Pump Horsepower CalculatorPump brake horsepower and motor size from flow and head, with efficiency and annual energy cost.Reynolds Number CalculatorThe Reynolds number and whether flow is laminar, transitional or turbulent.Tank Drain Time CalculatorTime for a tank to drain by gravity or pump - vertical or horizontal cylinder, rectangular and cone-bottom - with head, flow rates and a drain curve.
📐 Fasteners & Rivets 9
Rivet Edge Distance CalculatorHow far a rivet must sit from the edge to avoid tear-out - recommended minimum edge distance, a pass/fail check, and tear-out (shear-out) capacity.Rivet Grip Range CalculatorWhich blind (pop) rivet grip range fits your material - enter the stack thickness and rivet diameter to get the grip number, range and drill size.Rivet Length CalculatorWhat length rivet to buy for your grip - length = grip + tail allowance (about 1.5d for solid rivets), with standard-size rounding and a grip-to-diameter check.Rivet Pattern CalculatorLay out a rivet group over a plate - rows, columns and total count for a grid or staggered pattern, with pitch, gauge and edge checks.Rivet Pull-Out CalculatorWill a rivet hold in tension or pull through? Rivet tensile vs sheet pull-through capacity, the governing mode, and a pass/fail check.Rivet Shear Strength CalculatorWill the rivets hold? Shear capacity of a riveted joint per rivet and total, with a pass/fail verdict and the actual factor of safety against your load.Rivet Size CalculatorWhat diameter rivet for the joint - size it from sheet thickness, Unwin formula, or shear load, then round to the nearest standard size.Rivet Spacing CalculatorHow far apart to set rivets and how many a seam needs - pitch and rivet count with the usual 3d to 6d spacing and edge-distance checks.Rivet Type Selector: Blind vs Solid vs TubularWhich rivet type for your job? A four-question selector for blind vs solid vs tubular rivets, plus a side-by-side comparison.
⚡ Electrical Engineering 7
AC Impedance Calculator (Series RLC)Series RLC impedance, reactance, phase angle, power factor and resonant frequency at a given AC frequency.Capacitor & RC Time Constant CalculatorCapacitor energy, charge, RC time constant and charge/discharge voltage over time, with the 63% and 5-tau rules.Fault Current (Short-Circuit) CalculatorAvailable short-circuit current at a transformer secondary, with the minimum breaker interrupting rating (AIC).Motor Full-Load Amps (FLA) CalculatorMotor full-load amps for 3-phase, 1-phase and DC, with the NEC 125% conductor sizing figure.Power Factor Correction CalculatorCapacitor kVAR to correct power factor, with the apparent-power and current reduction it delivers.Three-Phase Power CalculatorReal, apparent and reactive power for a three-phase load, plus sizing current.Wire Size CalculatorMinimum wire size from ampacity and voltage drop, with the deciding factor shown.
📐 Structural Engineering 7
Beam Deflection CalculatorHow far a beam bends under load, checked against a safe deflection limit.Beam Load CalculatorReactions, shear and maximum bending moment for a loaded beam.Column Buckling CalculatorEuler buckling load from section, length and end conditions, with slenderness and a verdict.Load Combination CalculatorRank every ASCE 7 LRFD and ASD load combination from your nominal loads and find the governing case.Seismic Base Shear CalculatorSeismic base shear by the ASCE 7 equivalent lateral force method, with the R-factor and period cap and floor.Snow Load CalculatorRoof snow load by the ASCE 7 method with exposure, thermal, importance factors and the slope reduction.Wind Load CalculatorWind force on a wall, sign or panel by the ASCE 7 velocity-pressure method, with exposure and height.
📐 Civil Engineering 7
Bearing Capacity Calculator (Terzaghi)Ultimate and allowable bearing capacity of a shallow footing by the general bearing-capacity equation, with shape and groundwater.Concrete Volume CalculatorConcrete volume, bags and cost for slabs, footings, columns, walls and stairs, plus rebar.Excavation CalculatorExcavation volume for pits, trenches and piers, with soil swell, truckloads and haul cost.Rebar Development Length CalculatorRebar tension development length by the ACI 318 simplified method, with casting, coating and lightweight factors.Retaining Wall CalculatorGravity retaining wall stability - overturning, sliding and bearing checks with safety factors.Slope Stability Calculator (Infinite Slope)Infinite-slope factor of safety against sliding, with dry and seepage cases - the geotechnical slope check.Stormwater Runoff CalculatorPeak stormwater runoff by the Rational Method (Q = C i A), in cfs or m3/s, with surface coefficients.
📐 Thermodynamics & Heat Transfer 7
Heat Transfer CalculatorConduction, convection, resistance, U-value and LED junction temperature.Latent Heat CalculatorEnergy to melt, freeze, boil or condense a mass (Q = m L), with phase-change temperature, time and cost.LMTD & Heat Exchanger CalculatorLog mean temperature difference and heat duty (Q = U A LMTD) for counterflow or parallel-flow exchangers, with cross check.Pipe Heat Loss CalculatorRadial heat loss from an insulated pipe, in W/m and BTU/hr-ft, with the savings versus a bare pipe.R-Value CalculatorTotal R-value and U-factor of a layered wall or roof assembly, with a climate-zone code check.Sensible Heat CalculatorHeat energy to change a material temperature, in kWh and BTU, with heating time and cost.Thermal Expansion CalculatorLength change, shaft and hole diameter growth, and the expansion gap to leave.
📐 Material & Weight 6
Aluminum Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...Material Weight CalculatorFind the weight of any material in any shape. Choose a material, from steel and aluminum to brass, copper, titanium, plastic, wood, or glass, pick a shape, and...Pipe Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...Plate Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...Steel Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...Tube Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...
📐 HVAC 6
CFM and Air Changes (ACH) CalculatorFind the airflow (CFM or m3/h) a room needs for a target air-change rate, or the ACH a fan delivers. Room-type presets, metric and imperial.Duct Static Pressure CalculatorFind the static pressure of a duct run - velocity, friction rate and total static pressure - for round or rectangular ducts. Darcy/Swamee-Jain, metric and imperial.Duct Velocity CalculatorFind air velocity in a round or rectangular duct from airflow and size, or size a duct for a target velocity. Recommended-range check, metric and imperial.Fan Laws (Affinity) CalculatorApply the fan affinity laws: change fan speed or impeller diameter and get the new airflow, pressure and power. Shows the cube-of-speed energy saving.Psychrometric CalculatorEnter dry-bulb temperature plus relative humidity, dew point or wet-bulb to get full moist-air properties: dew point, RH, wet-bulb, humidity ratio, enthalpy and specific volume.Ventilation Rate Calculator (ASHRAE 62.1)Required outdoor air by ASHRAE 62.1: combine the per-person and per-area rates for your occupancy type to size fresh-air ventilation. With Ez and CFM/L-s output.
📐 Sheet Metal 5
Bend Allowance CalculatorCalculate sheet metal bend allowance, bend deduction and outside setback from bend angle, thickness, radius and K-factor.Bend Deduction CalculatorCalculate sheet metal bend deduction and flat blank length from bend angle, thickness, inside radius and K-factor.Flat Pattern CalculatorCalculate the flat blank length for a multi-bend sheet metal part from its outside dimensions and bend deductions.K-Factor CalculatorBack-calculate the sheet metal K-factor from a measured test bend or a known bend allowance.Sheet Metal Weight CalculatorWork out the weight of any steel shape, then build a cut list and price the whole job. Pick a shape or a standard size, enter the dimensions,...
📐 Cutting & Process 5
Cutting Time CalculatorAdd cutting, piercing and handling into a realistic cycle time and parts-per-hour.Edge Prep CalculatorTurn bevel angle, root face, gap and thickness into groove area and weld metal weight for a single-V joint.Laser Cutting CalculatorBreak a laser cut into labor, assist gas and electricity cost from length, speed and machine power.Plasma Cutting CalculatorSplit a plasma cut into labor, consumables and gas/power cost from length, speed and pierces.Waterjet Cost CalculatorTrack garnet used, abrasive cost, labor and pump from cut length, speed and abrasive flow.
📐 Machining 5
Drill Speed CalculatorCalculate drill RPM and feed rate from drill diameter, cutting speed and feed per revolution.End Mill Speed CalculatorCalculate end mill spindle RPM and table feed from cutter diameter, cutting speed, chip load and flute count.Feed Rate CalculatorCalculate machining feed rate (IPM or mm/min) from RPM, chip load per tooth and number of flutes.RPM CalculatorConvert cutting speed and tool diameter into spindle RPM for milling, drilling and turning.Tap Drill CalculatorFind the correct tap drill size for metric or imperial threads from major diameter, pitch or TPI and thread engagement.
📐 Welding 5
Fillet Weld CalculatorCalculate fillet weld throat, cross-section area, weld metal volume and weight from leg size and length.Weld Time CalculatorCalculate welding arc time and total job time from weld length, travel speed, passes and operator factor.Welding Cost CalculatorCalculate total welding cost broken into labor, filler wire and shielding gas.Welding Gas CalculatorCalculate shielding gas used, cylinders needed and cost from flow rate and arc time.Welding Wire CalculatorCalculate filler wire and spools needed from weld size, length and deposition efficiency.
📐 Layout & Design 4
Bolt Circle CalculatorGet X-Y coordinates for every hole on a bolt circle from diameter, hole count and start angle.Hole Pattern CalculatorGet X-Y coordinates for a grid or linear row of holes from count, pitch and angle.Polar Coordinate CalculatorConvert between polar radius and angle and X-Y coordinates both ways, with an optional pole offset.Triangle Layout CalculatorSolve all sides, angles, area and vertex coordinates from three sides or two sides and the included angle.
📏 Conversions 4
Engineering Unit ConverterConvert pressure, force, torque, energy, power, flow and temperature, with a full unit table.Flow Rate ConverterConvert flow rate between GPM, L/s, L/min, m3/h, m3/s, CFM and ft3/s instantly, with common equivalents.Power ConverterConvert power between watts, kW, horsepower, BTU/hr, ft-lb/s and tons of refrigeration, with common equivalents.Torque ConverterConvert torque between N-m, lb-ft, lb-in, oz-in, kgf-m and kN-m instantly, with common equivalents.
📐 Tube & Pipe 4
Pipe Cut Length CalculatorCalculate the pipe length to cut between fittings from center-to-center measurement, take-out and engagement.Pipe Surface Area CalculatorCalculate pipe external and internal surface area and coating needed from diameter and length.Pipe Volume CalculatorCalculate pipe internal volume, capacity in gallons or litres and water weight from diameter, wall and length.Tube Notcher CalculatorCalculate fishmouth saddle notch depth and coping profile for joining round tubes at any angle.
📐 Materials 3
Corrosion Rate CalculatorCorrosion rate by weight loss, thickness loss or electrochemical method in mpy, mm/yr and um/yr, with corrosion-allowance remaining life and a pass/fail service-life check.Hardness Conversion CalculatorConvert hardness between Vickers, Brinell, Rockwell C and Rockwell B, with a steel tensile-strength estimate. ASTM E140-style correlations.Thermal Stress CalculatorThermal stress for restrained parts: fixed, partial, free, pipe, beam, rail, bolted and differential modes. Expansion, stress, force, yield pass/fail and charts.
What you can calculate here
The library spans the core engineering disciplines. Mechanical tools cover stress, strain, factor of safety, beam deflection, and shaft and gear design. Fluid and thermal tools handle Reynolds number, pipe flow, pressure drop, pump power, and heat transfer. Materials tools cover hardness conversion, corrosion rate and remaining life, and thermal stress. Electrical tools work out resistance, voltage drop, and power. Fabrication tools size welds, bolts, sheet-metal bends, and pipe cuts. Together they cover the day-to-day numbers across design, analysis, and the shop floor.
Who these calculators are for
Practising engineers use them for fast sanity checks before committing to a full analysis. Students and apprentices use them to see a formula and a worked example side by side. Machinists, welders, and fabricators use the shop tools to size fasteners, welds, and cuts. Maintenance and reliability teams use the corrosion and remaining-life tools to plan inspections. If you need a defensible number quickly, start here and confirm critical work against the relevant code.
Getting accurate results
A few habits keep the numbers reliable:
- Keep units consistent. Most tools state the expected units beside each field.
- Use real material properties (yield strength, modulus, surface roughness) rather than generic defaults for anything load-bearing.
- For fluid problems, check whether flow is laminar or turbulent before trusting a correlation.
- Treat every result as a first-pass estimate. Safety-critical design should always be verified against the governing standard.
Frequently asked questions
Are these calculators free?
Yes. Every engineering and fabrication calculator here is free, with no account and no usage limit.
Do you cover both design and fabrication work?
Yes. This hub includes the full fabrication set alongside the engineering tools, so design calculators and shop-floor calculators live in the same place.
How accurate are the results?
The formulas are standard engineering equations and are accurate for the inputs you provide. They are intended for estimation and learning, not as a replacement for stamped calculations on regulated work.
Will they work on my phone?
Yes. Every tool is responsive and works the same on phone, tablet, and desktop.
Which calculator should I start with?
Pick the quantity you need. Sizing a beam? Beam Deflection. Checking a pipe? Reynolds Number or Pipe Flow. Tightening a joint? Bolt Torque. Each tool links to the related ones.
Do you store the numbers I enter?
No. Everything is calculated in your browser, and your inputs are not saved or sent anywhere.