Engineering & construction
517 engineering and construction calculators: electrical circuits, mechanics, materials, structures and building quantities. Results with the formula and units in view, so you can check a design before you build it, free in your browser.
Newton's cradle calculator
Tell it how many balls strike the row and how fast, and it gives what leaves the far end: two balls arriving at 1.5 m/s send two balls out at 1.5 m/s in the…
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Parallel axis theorem calculator
Move a known moment of inertia to a parallel axis: a 3 kg part with 2.5 kg·m² about its centre of mass, turning about an axis 0.4 m away, adds 0.48 and reaches…
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Power to overcome drag calculator
Holding 20 m/s against 100 N of drag takes 2000 W, since at steady speed the driving force exactly balances the resistance.
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Rolling down incline calculator
A solid cylinder, with inertia factor 0.5, rolling down a 30° ramp speeds up more slowly than a block sliding without friction, because part of the energy goes…
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Rotational work calculator
A constant 10 N·m torque turning a shaft through 2 radians does 20 J of work. Enter the torque and the angle in radians to get the work in joules, negative when…
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Spring launch speed calculator
A spring of 200 N/m compressed 0.1 m launches a 0.5 kg mass at 2 m/s. Enter stiffness, compression and mass to get the launch speed and the stored energy…
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Belt and pulley speed calculator
A 4-unit pulley turning at 1750 rpm drives a 10-unit pulley at 700 rpm, a ratio of 0.4. Enter the driver speed and both diameters to check a belt drive before…
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Orbit total energy calculator
A 1000 kg satellite circling a 5.972 × 10²⁴ kg planet at 6,771,000 m from its centre has a negative total energy, which means it is bound.
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Orbital angular momentum calculator
A satellite 7,000,000 m from the planet's centre moving at 7500 m/s along the local horizontal carries 52,500,000,000 m²/s of angular momentum per unit of its…
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Specific orbital energy calculator
A low Earth orbit with a 6778 km semi-major axis has a specific energy of roughly minus twenty-nine million joules per kilogram, so the satellite is bound.
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Surface gravity from density calculator
A body with a mean density of 5514 kg/m³ and a radius of 6371000 m has a surface gravity of 9.8212937284 m/s², like Earth.
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Gravitational binding energy two masses calculator
The Earth and the Moon, 384400000 m apart, have a gravitational potential energy of −7.6130121671e28 J.
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First-class lever calculator
On a crowbar with the fulcrum 0.5 m from a 120 N load and 2 m from your hand, a push of 30 N holds it in balance.
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Friction for rolling without slipping
A solid cylinder on a 30° incline needs a static friction coefficient of at least about 0.19 to roll without slipping.
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Seconds pendulum length calculator
Under standard Earth gravity of 9.80665 m/s², a pendulum that takes one second per swing and two per full cycle needs a length close to one metre.
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SHM displacement calculator
An oscillator with a 0.5 m amplitude and an angular frequency of π rad/s, starting at its maximum, is back at equilibrium after 0.5 s.
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SHM total energy calculator
A 200 N/m spring oscillating with a 0.1 m amplitude holds 1 J of total energy, the same at every instant of the cycle.
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Force to Tip an Object Calculator
A block weighing 980 N with a 0.6 m base, pushed at a height of 1.2 m, starts to tip under a horizontal force of 245 N.
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Vertical spring stretch calculator
A 2 kg mass hanging from a 100 N/m spring under 9.8 m/s² gravity stretches it by 0.196 m. Enter mass, spring constant and gravity to get the static sag and the…
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Apparent weight in fluid calculator
A 100 N object fully under water, displacing 0.002 m³, reads 80.38 N on a scale: the calculator works out the buoyant force, 19.62 N here, and subtracts it from…
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G-force calculator
An acceleration of 19.6133 m/s² is exactly 2 g: enter either value and get both, with the sign kept so braking and speeding up stay apart in your test data or…
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Ladder equilibrium calculator
A 200 N ladder, 5 m long and set at 60 degrees to the floor, needs a floor friction coefficient of at least 0.288675134595 so its foot does not slide.
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Moment of a force calculator
A 20 N push applied 0.4 m from a hinge, measured at right angles to the force, turns it with a moment of 8 N·m.
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Pulley system effort calculator
How hard do you have to pull? With four strands holding 400 N, the ideal pull is 100 N, a quarter of the load; two strands halve it.
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Stokes drag force calculator
A sphere of radius 0.001 m moving at 0.01 m/s through a fluid of 0.001 Pa·s feels a drag of 1.88496e-7 N.
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Weight at latitude calculator
A 70 kg mass reads 686.4655 N at the poles and a little less toward the equator, where Earth's spin takes about 0.034 m/s² off gravity.
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Maximum Power Transfer Calculator
A 12 V source with 6 Ω of internal resistance gives at most 6 W, into a 6 Ω load at 6 V and 1 A. Enter the open-circuit voltage and the source resistance to get…
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Two-node voltage analysis calculator
A 1 kΩ branch enters as 0.001 S: give the three branch conductances and the current entering each node, and get both node voltages of a two-node resistive…
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Series-parallel resistor network calculator
A 100 Ω resistor, a 220 Ω and 330 Ω parallel pair and a 1 kΩ resistor in series come to 1232 Ω. Describe series and parallel groups nested inside one another…
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Watt-hours from power and time calculator
A 60 W device running for 8 hours uses 480 watt-hours, or 0.48 kWh: enter the average power and the hours, using decimals such as 1.5 for ninety minutes, and…
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NTC thermistor temperature from resistance calculator
A 10 kΩ NTC that measures exactly 10 kΩ is at its 25 °C reference, which is 298.15 K or 77 °F. Enter the measured resistance, the nominal value and beta to read…
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Six-band resistor color code calculator with temperature coefficient
Brown-black-black-red-brown-brown is a 10,000 Ω resistor with ±1 % tolerance and a 100 ppm/°C temperature coefficient.
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RC Discharging Voltage at Time Calculator
12 V on a 100 µF capacitor discharging through 10 kΩ keeps only about 13.5 % after 2 seconds, two time constants.
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Supercapacitor backup time calculator
A 100 F bank charged to 5.4 V and drained to 3 V keeps a 10 W load running for about 90.72 seconds at a converter efficiency of 0.9.
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Coupled inductors in series calculator
Coils of 0.01 H and 0.04 H with 0.006 H of mutual inductance total 0.062 H in series aiding and 0.038 H in series opposing.
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Parallel plate capacitor area calculator
A 1 nF target with plates 1 mm apart and a dielectric constant of 2.2 needs a square overlap just over 22 cm on each side.
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Toroid inductance calculator
Find the ideal inductance of a toroidal coil, for example 100 turns on a core with a relative permeability of 2000, a 0.0001 m² cross-section and a 0.1 m…
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AC form factor and crest factor calculator
A 120 V RMS sine with a rectified average of 108.037 and a peak of 169.706 gives a form factor of 1.1107 and a crest factor of 1.4142.
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Impedance polar to rectangular converter
An impedance of 50 Ω at 30° splits into 43.3012701892 Ω of resistance and 25 Ω of inductive reactance.
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Three-phase power calculator
400 V between lines, 32 A per line and a power factor of 0.85: enter those three figures and get the real power of a balanced three-phase load in watts and…
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Peak voltage from RMS calculator for sine waves
A 10 V RMS sine wave peaks at about 14.142 V and spans about 28.284 V peak to peak: enter the RMS voltage and get both, multiplied by the square root of two.
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Series diode voltage drop calculator
Three diodes dropping 0.7, 0.7 and 0.65 V use 2.05 V, so a 12 V supply leaves 9.95 V for the load.
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LED resistor by color calculator
A red LED on 5 V at 20 mA needs 150 Ω, and you never have to look up its forward voltage: choose the color, enter supply and current, and get the resistor, its…
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Common Emitter Voltage Gain Calculator
With 4700 Ω on the collector, 100 Ω of unbypassed emitter resistance and 0.04 S of transconductance, a common-emitter stage gains -37.6 V/V, inverting the…
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MOSFET Drain Current in Saturation Calculator
A gate overdrive of 2.5 V and a k of 0.004 A/V² give 12.5 mA of drain current. Enter those two values and get the ideal square-law current in amperes and…
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Rectifier peak inverse voltage calculator
On a 12-0-12 V center-tapped rectifier each diode must block twice the peak of one 12 V half-winding, while bridge and half-wave diodes see a single peak.
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BCD to binary converter
Decode packed 8421 BCD into its decimal value and plain binary: 0010 0101 1001 is 259, which is 100000011 in binary.
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Binary division calculator
Divide two unsigned binary numbers and get the exact quotient and remainder with every restoring step: 110101 divided by 101 gives 1010, remainder 11.
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Ratio to gain dB calculator
A voltage ratio of 2 is a gain of about 6 dB. Say whether your ratio compares voltages or powers and the calculator applies 20 or 10 times the logarithm, so the…
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Binary Counter Maximum Count Calculator
A counter with 4 flip-flop stages has 16 states and counts from 0 to 15, so its largest value is one less than its modulus.
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Binary decoder outputs calculator
Four input lines make a 4-to-16 decoder: sixteen outputs, and a block that starts at 4096 ends at 4111, or 0x1000 to 0x100F.
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Bit Rotate Calculator
Rotating 150 three places left in an 8-bit register gives 180, or 10110100 in binary: bits that fall off one end come back at the other.
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Buck-boost converter duty cycle calculator
Turning a 12 V supply into a −5 V rail needs a duty cycle of 0.294118, about 29.4118% of each switching period.
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Charge pump voltage calculator
Three doubler stages driven by a 12 V peak wave give an ideal 72 V with no load, six times the input peak.
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Clock frequency and period calculator
A 100 MHz clock has a period of 10 ns, and a 20 ns period means 50 MHz. Enter either the frequency or the period, plus an optional interval to count cycles, and…
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555 astable resistor and capacitor calculator
Ask for 1000 Hz at 60 % duty and it picks a 5.6 nF capacitor from the E12 series, then works out both timing resistors around it for a classic 555 astable.
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Peukert Battery Capacity Calculator for Lead-Acid Batteries
A 100 Ah battery rated at 20 hours was measured at only 5 A, so a heavier load gets fewer amp-hours out of it.
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Solar array energy sizing calculator
Covering 30 kWh a day with 5 peak sun hours and 20 % system losses takes a 7500 W panel array. Enter daily energy, sun hours and losses to get the exact…
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Junction temperature calculator
A part dissipating 2.5 W through 40 °C/W runs 100 °C above ambient, so at 25 °C its junction reaches 125 °C.
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Parallel conductor ampacity calculator
Three identical conductors rated 200 A each add up to 600 A, and a 0.8 adjustment factor brings that to 480 A.
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