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.
Magnetic force calculator
A charge of 0.002 C crossing a 0.5 T field at 500,000 m/s feels 500 N: enter the charge, its speed, the field and the angle between motion and field to get the…
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Force on a current-carrying wire calculator
A 0.5 m wire carrying 2 A across a 0.4 T field at right angles feels 0.4 N: enter the current, the length inside the field, the field strength and the angle to…
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555 timer calculator
With 1000 Ω, 2200 Ω and 1 µF, a 555 astable repeats about every 3.7 ms and stays high just under 60 % of the time.
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555 timer monostable calculator
10 kΩ and 10 µF give a 555 one-shot a 110 ms pulse with the classic 1.1 × R × C rule. Enter the timing resistor and capacitor to get the pulse width in seconds…
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Non-inverting amplifier calculator
Rf of 10 kΩ over Rg of 1 kΩ gives a non-inverting op-amp a gain of 11, about 20.8 dB, with the signal polarity kept.
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Parallel-plate capacitor calculator
Two plates of 0.01 m² (100 cm²) 1 mm apart in air make 88.542 pF. Enter the overlap area, the gap and the dielectric constant to get the ideal parallel-plate…
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Power gain dB calculator
One watt in and two watts out is a gain of about 3 dB. Enter the input and output power in the same unit to get the gain in decibels, the linear ratio and…
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PWM duty cycle calculator
2 ms on in a 10 ms period is a 20 % duty cycle, and on a 5 V supply that averages 1 V. Enter on-time, period and supply voltage to get the duty fraction…
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RC filter cutoff calculator
A 1 kΩ resistor with a 1 µF capacitor gives a cutoff near 159 Hz, the −3 dB point where a low-pass RC filter starts cutting higher frequencies and a high-pass…
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RC time constant calculator
1 kΩ times 1 µF gives a time constant of 1 ms, and five of them, 5 ms, is the usual settling window.
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Wire resistance calculator
A 10 m copper wire with a 1 mm² cross-section has about 0.168 Ω of resistance. Enter resistivity, length and area to get the DC resistance of any uniform wire…
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Series resistance calculator
100 Ω, 220 Ω and 330 Ω in series add up to 650 Ω. List the resistors in a single current path and get the one total that replaces the whole chain, for current…
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RL filter cutoff calculator
A 1000-ohm resistor and a 1 mH inductor put the 3 dB corner of a first-order RL filter at about 159.155 kHz.
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RL time constant calculator
A 0.1 H coil in series with 50 Ω has a time constant of 2 ms, the time its current needs to cover about sixty-three percent of a step.
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Slew rate from full-power bandwidth
10 V peak at 100 kHz needs an op-amp that slews at least 6283185 V/s, a little over 6 V/µs. Enter the peak output and the full-power bandwidth to get the…
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Johnson noise calculator
A 50 Ω resistor at 290 K over a 1 MHz bandwidth produces about 900 nV RMS of Johnson noise. Enter the resistance, absolute temperature and noise bandwidth to…
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Voltage drop calculator
20 A through 50 m of 12 AWG copper loses a little over 10 V there and back. Enter the gauge, one-way length, current and copper or aluminium to get the…
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Voltage gain dB calculator
An amplifier that turns 1 V into 10 V has a gain of 20 dB: enter the input and output voltage and get the ratio and the decibel figure, using twenty times the…
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Watts to dBm calculator
1 W is 30 dBm and 1 mW is 0 dBm: enter a power in watts or milliwatts and get its level in dBm, ten times the base-10 logarithm of the power over one milliwatt.
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Watts, volts & amps calculator
120 V at 2 A is 240 W: give any two of power, voltage and current and the calculator works out the third from power equals voltage times current, and shows…
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Frequency to wavelength calculator
A 100 MHz radio carrier has a wavelength of about 3 metres in a vacuum: enter a frequency in hertz or a wavelength in metres and get the other, worked out from…
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Wheatstone bridge calculator
With ratio arms of 100 and 200 ohms and a known arm of 50 ohms, the unknown Rx is 100 ohms: enter the three known resistances of a balanced bridge and get the…
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Zener diode resistor calculator
A 5.1 V zener on a 12 V rail feeding 20 mA needs a 345 Ω series resistor that dissipates 0.138 W, so a 0.5 W part is suggested.
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Angular velocity calculator
Sweeping 2π radians in 2 seconds is an angular velocity of π rad/s, or 30 rpm: enter an angle and a time, or just the RPM, and the calculator returns ω in…
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Atwood machine calculator
With 5 kg and 3 kg hanging over an ideal pulley, the system accelerates at 2.4525 m/s² and the rope carries 36.7875 N, with the 5 kg side going down: the…
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Average velocity calculator
Moving 100 metres in 20 seconds is an average velocity of 5 m/s, or 18 km/h: enter the total displacement and the time, and the calculator gives both units plus…
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Banked curve calculator
A curve with a 50 m radius taken at 20 m/s needs a bank of 39.1970508975 degrees if no friction is to help: the calculator solves tan θ = v²/(r·g) and gives the…
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Centripetal acceleration calculator
An object moving at 10 m/s on a 5 m radius needs 20 m/s² of inward acceleration to stay on its circle.
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Centripetal force calculator
A 2 kg mass moving at 10 m/s on a 5 m radius needs a 40 N pull toward the centre. Use it to check string tension, the grip a car needs on a curve, or a homework…
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Coefficient of friction calculator
A friction force of 20 N against a normal force of 50 N gives a coefficient of friction of 0.4. Enter both forces in the same unit and get the dimensionless…
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Elastic collision calculator
A 2 kg body at 3 m/s hitting a resting 1 kg body leaves at 1 m/s while the second shoots off at 4 m/s.
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Force calculator
A 5 kg mass accelerating at 4 m/s² needs a net force of 20 N: give any two of force, mass and acceleration and the calculator solves the third with Newton's…
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Free fall calculator
Drop something from 19.62 m with gravity at 9.81 m/s² and it lands after 2 seconds at 19.62 m/s: enter any height to get both the fall time and the impact…
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Hooke's law calculator
A spring with a constant of 10 N/m stretched by 2 m pulls with 20 N. Enter any two of force, spring constant and displacement and get the third from Hooke's law…
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Horizontal projectile motion calculator
A ball that leaves a 20 m ledge horizontally at 15 m/s hits the ground about 2 seconds later. Enter the launch height and the sideways speed to get the fall…
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Impulse calculator
A 50 N push lasting 0.02 s delivers an impulse of 1 N·s, and the object's momentum changes by exactly that amount.
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Inclined plane calculator
A 10 kg block on a 30-degree slope with a friction coefficient of 0.2 accelerates downhill at just over 3 m/s² and presses on the surface with about 85 N.
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Kinematics distance calculator
An object that starts at 10 m/s and accelerates at 2 m/s² for 5 s covers 75 m. Enter the initial velocity, the constant acceleration and the elapsed time to get…
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Final velocity calculator
Starting at 10 m/s and accelerating at 2 m/s² for 5 s, an object ends up at 20 m/s. Enter the initial velocity, the acceleration and the elapsed time, with…
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Kinetic energy calculator
A 2 kg mass moving at 3 m/s carries 9 J of kinetic energy. Enter any two of mass, speed and energy and get the third from KE = ½mv², or all three to check a…
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Moment of inertia calculator
A solid disc of 2 kg and 3 m radius has a moment of inertia of 9 kg·m² about its central axis. Pick ring, disc, sphere or rod, enter the mass and the radius or…
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Momentum calculator
Multiply mass by velocity and get linear momentum with its sign: 2 kg moving at 5 m/s carries 10 kg·m/s, and a reversed velocity gives a negative result, so…
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Newton's second law calculator
Give any two of mass, acceleration and net force and the third appears with its working: a 10 kg body accelerating at 2 m/s² needs a net force of 20 N.
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Pendulum length calculator
Tell it the swing time you want and get the string length: a 2-second period under 9.81 m/s² needs just under 1 m.
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Power calculator
Divide the work done by the time it took: 1000 J delivered in 2 seconds is 500 W of average power, and the result also comes in mechanical horsepower for engine…
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Power from force and velocity
A 50 N force pulling a load along at 4 m/s delivers 200 W, because power is force times velocity when both point the same way.
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Projectile from height calculator
Throw at 20 m/s and 45 degrees from 10 m up and it lands 49.0821614194 m away after 3.4706329175 seconds under 9.81 m/s².
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Pulley mechanical advantage calculator
Four rope strands holding a 400 N load give an ideal mechanical advantage of 4 and a pull of just 100 N.
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Rotational kinetic energy calculator
A flywheel with a moment of inertia of 2 kg·m² spinning at 4 rad/s stores 16 J. Enter the moment of inertia and the angular velocity to get the energy held in…
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Spring constant calculator
A spring that stretches 0.25 m under a 50 N force has a spring constant of 200 N/m. Enter the force and the extension or compression to get its stiffness, with…
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Terminal velocity calculator
An 80 kg body with a drag coefficient of 1 and 0.7 m² of area, falling through air of 1.225 kg/m³, settles at 42.776304713 m/s.
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Torque calculator
A force of 10 N on a 0.5 m lever arm at 90° gives a torque of 5 N·m. Enter force, arm length and angle to get the turning effect for bolts, doors or statics…
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Work done calculator
Pushing with 10 N through 5 m in the direction of motion does 50 J of work; at 90° the same push does none.
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Estimate EV charging time remaining from battery size and charger power
Know when the car will be ready: a 75 kWh battery going from 20% to 80% needs 45 kWh, which takes about 4 hours and 5 minutes on an 11 kW charger.
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Estimate device battery life from battery capacity and current draw
A 2400 mAh battery feeding a device that averages 120 mA lasts about 20 hours: capacity divided by average current gives the ideal runtime.
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Round-trip average speed
Out at 60 and back at 40 over the same distance averages 48, not 50: the calculator takes the harmonic mean, twice the product of the speeds over their sum, and…
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Braking distance calculator
At 20 m/s with a steady deceleration of 5 m/s², a vehicle needs 40 m to stop. Enter speed and deceleration to get the braking distance in metres for safety…
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Vertical throw max height calculator
Thrown straight up at 20 m/s with a gravity of 10 m/s², an object rises 20 m and reaches the top after 2 s.
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Crosswind heading calculator
At 100 knots of airspeed with a 20-knot crosswind, you must crab about eleven and a half degrees into the wind and your ground speed drops to almost…
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Thrown downward motion calculator
Thrown down at 5 m/s with a gravity of 9.81 m/s², an object falls 29.62 m in 2 s and reaches 24.62 m/s.
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