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.
Battery depth of discharge calculator
Turn a chosen depth of discharge into usable amp-hours, watt-hours and an estimated cycle life: a 400 Ah, 48 V bank at 60 % gives 240 Ah and 11,520 Wh, and a…
Free · Runs in your browser
Binary multiplication calculator
Multiply two binary numbers and see every shift-and-add row: 1011 times 110 gives 1000010, built from one skipped row and two added ones.
Free · Runs in your browser
Binary to BCD converter
Turn a binary number into the 8421 BCD pattern a multi-digit display needs: 101010 is 42, which becomes the groups 0100 and 0010.
Free · Runs in your browser
Bits Needed for Values Calculator
Find the smallest binary width that fits your values: 1000 distinct states need 10 bits, which give 1024 patterns.
Free · Runs in your browser
Bitwise XOR calculator
Combine two integers bit by bit with exclusive OR: 12 XOR 10 gives 6, because 1100 and 1010 differ in exactly two places.
Free · Runs in your browser
Boolean expression truth table calculator
Type a logic expression with AND, OR and NOT and get its complete truth table: A AND B gives four rows, with 1 only where both inputs are 1.
Free · Runs in your browser
Boost converter duty cycle calculator
Stepping 5 V up to 12 V takes a duty cycle of about 0.5833 and gives a voltage gain of 2.4, and this calculator works out both from your two voltages.
Free · Runs in your browser
Switching converter input current calculator
A 50 W load fed from 12 V at 90 % efficiency draws just over four and a half amperes on average, more than a lossless estimate.
Free · Runs in your browser
DAC output voltage calculator
An 8-bit converter with a 5 V reference turns code 128 into exactly 2.5 V. Enter the digital code, the reference voltage and the resolution to get the output…
Free · Runs in your browser
dB to gain ratio calculator
Twenty decibels is a voltage ratio of 10 but a power ratio of 100, so choosing the right kind matters.
Free · Runs in your browser
Gray code to binary calculator for encoder values
Gray 0111 decodes to binary 0101, which is 5 in decimal. Paste the word your encoder reports, with or without a 0b prefix, and get ordinary binary with the same…
Free · Runs in your browser
Johnson counter states calculator
Four flip-flops wired as a Johnson counter give 8 unique states, twice the number of stages. Enter the stage count to get that figure, the plain ring count and…
Free · Runs in your browser
Monostable timer period calculator
A 47 kΩ resistor and a 10 µF capacitor give a 0.517 s pulse (517 ms) with the usual factor of 1.1.
Free · Runs in your browser
MOSFET switching loss calculator
Hard-switching 48 V and 10 A with 50 ns and 40 ns edges at 100 kHz dissipates 2.16 W in the MOSFET.
Free · Runs in your browser
555 astable frequency calculator
With RA at 1000 Ω, RB at 10000 Ω and C at 1 µF, a 555 astable has a timing term of 21000 Ω, RA plus twice RB.
Free · Runs in your browser
Op-amp buffer follower calculator
Put 2.5 V on the non-inverting input of an op-amp follower and 2.5 V comes out: a gain of one and no inversion.
Free · Runs in your browser
Op-amp full-power bandwidth calculator
An op-amp with a 6.283 V/µs slew rate can swing 10 V peak up to 100 kHz before the sine turns into a triangle.
Free · Runs in your browser
Op-amp integrator calculator
2 V into 10 kΩ and 1 µF makes an ideal op-amp integrator ramp at −200 V/s, with a 10 ms time constant.
Free · Runs in your browser
Product of sums maxterm calculator
List the truth-table rows where the output is 0 and get the canonical product of sums: rows 0, 2, 5 and 7 for A, B and C become ΠM(0, 2, 5, 7), written out as…
Free · Runs in your browser
PWM resolution bits calculator
A 72 MHz timer running PWM at 20 kHz has 3,600 counts per period, which means 11 whole bits of duty resolution.
Free · Runs in your browser
Signed magnitude representation calculator
Negative 37 at eight bits is 10100101: the first bit holds the sign and the other seven hold the magnitude.
Free · Runs in your browser
Transistor power dissipation calculator
10 V across collector and emitter at 0.5 A means the transistor turns 5 W into heat. Enter Vce and Ic to get collector dissipation in watts, the figure to check…
Free · Runs in your browser
UART frame time calculator
At 115200 baud with 8N1, each frame is 10 bits, so the line carries at most 11520 frames per second.
Free · Runs in your browser
XOR checksum calculator
Turn the bytes of a frame into its one-byte XOR checksum: a five-byte message comes out as 66, written 0x42 in hexadecimal and 01000010 in binary.
Free · Runs in your browser
Solar battery bank sizing calculator
50 Ah a day for 3 days of autonomy at 50 % depth of discharge needs a 300 Ah bank: 150 Ah of usable charge, doubled so no more than half is ever drawn.
Free · Runs in your browser
Wire gauge selection calculator
For 20 A over a 30 m run at 120 V with a 3 % limit, copper needs AWG 9. Enter current, one-way length, voltage, allowed drop, material and circuit type to get…
Free · Runs in your browser
Fuse I²t melting calculator
A 500 A fault lasting 0.02 seconds delivers 5000 A²s, 125 % of a 4000 rating, so the melting threshold is exceeded by 1000.
Free · Runs in your browser
Thermal resistance stack calculator
1.2, 0.3 and 4.5 °C/W in series make 6 °C/W, so 18 W raises the junction by 108 °C and, at 25 °C ambient, it reaches 133 °C.
Free · Runs in your browser
Wire ampacity derating calculator
A 30 A wire rated 90 °C, in 40 °C air with six current-carrying conductors, drops to 21.84 A. Enter the table rating, ambient temperature, insulation column and…
Free · Runs in your browser
dB attenuation calculator
An attenuation of 6 dB leaves about half the voltage and about a quarter of the power. Enter one figure in decibels from a pad, a cable table or a filter sheet…
Free · Runs in your browser
Power bank phone charges calculator
A 20000 mAh power bank at 85 % efficiency delivers about 17000 mAh: four full charges of a 4000 mAh phone, with a quarter of a charge to spare.
Free · Runs in your browser
SWR from reflection coefficient calculator
A reflection coefficient of 0.2 means an SWR of 1.5 and about 14 dB of return loss. Enter the reflection magnitude or your forward and reflected power readings…
Free · Runs in your browser
Standby power cost calculator
A 5 W charger plugged in all day, every day, uses 43.8 kWh a year. Enter the idle watts and your price per kWh to see what that standby draw costs per day…
Free · Runs in your browser
Area by coordinates calculator
The corners (0,0), (4,0), (4,3) and (0,3) enclose an area of 12, listed counterclockwise. Paste a lot’s corner coordinates in boundary order, closed or open…
Free · Runs in your browser
Azimuth and distance from coordinates calculator for survey stations
From a station at 5000 E, 10000 N to one at 5125.5 E, 10175.25 N, the target lies 125.5 east and 175.25 north, at a grid azimuth just over thirty-five and a…
Free · Runs in your browser
Band brake torque calculator
A tight-side tension of 1200 N and a slack side of 400 N on a drum of radius 0.25 m give a braking torque of 200 N·m.
Free · Runs in your browser
Metal bar weight by material
A 20 mm steel rod 1 m long weighs about 2.466 kg at 7850 kg/m³; the same size in aluminum, at 2700 kg/m³, is far lighter.
Free · Runs in your browser
Simply supported center-load deflection calculator
A center load of 48 on a span of 2, with a modulus of 200 and a second moment of area of 4, gives a midspan deflection of 0.01 in coherent units.
Free · Runs in your browser
Bearing life hours calculator
An L10 rating of 50 million revolutions at 1200 RPM equals 694.444444 operating hours, about 28.935185 days of continuous running.
Free · Runs in your browser
Belt Wrap Angle Calculator for Open Belt Drives
Pulleys of 100 and 250 with their centers 600 apart leave the belt wrapped 165.638488° around the small pulley, or 2.890936991 radians.
Free · Runs in your browser
Bolt group eccentric shear calculator
Four bolts on a 3 by 3 square with 1000 pushing down 3 units from the centroid: the worst bolt takes 500 downward plus 250 sideways, while the direct share is…
Free · Runs in your browser
Overhead conductor tension calculator
A 100 m span carrying 1 N per metre with 2 m of midspan sag needs 625 N of horizontal tension under the parabolic rule for level spans.
Free · Runs in your browser
Conductor Resistance Calculator
A 25 m conductor with a 2.5 mm² cross-section and a resistivity of 1.68 × 10⁻⁸ ohm-metres has a resistance of 0.168 ohms.
Free · Runs in your browser
Pipe continuity velocity calculator
When the inlet area is twice the outlet area, a liquid entering at 2.5 m/s leaves at 5 m/s. Give the inlet velocity and the area ratio to check contractions and…
Free · Runs in your browser
Convective Heat Transfer Calculator
A 2 m² surface at 80 °C in a fluid at 20 °C, with a film coefficient of 25 W/m²·K, gives off 3000 W by convection.
Free · Runs in your browser
Crank mechanism torque calculator
At 90 degrees the whole piston force turns the crank, while at 0 degrees even a large force gives zero torque.
Free · Runs in your browser
Critical Crack Length Calculator
With a toughness of 50 MPa√m, a stress of 250 MPa and the default geometry factor of 1.12, the critical crack is about 10 mm.
Free · Runs in your browser
Electrical demand load calculator
A connected load of 125 kVA with an 80 percent demand factor gives a diversified demand of 100 kVA, a reduction of 25 kVA.
Free · Runs in your browser
Direct Shear Stress Calculator for Pins, Bolts, and Rivets
A 12000 N force on a pin in double shear, with 0.0002 m² per plane, gives an average shear stress of 30 MPa.
Free · Runs in your browser
Duct air velocity calculator
An airflow of 1.2 m³/s through a duct with 0.3 m² of internal area moves at 4 m/s on average, or 14.4 km/h.
Free · Runs in your browser
Engineering Stress from Load Calculator
A 12500 N load on a tensile specimen with 50 mm² of original area gives an engineering stress of 250 MPa.
Free · Runs in your browser
Straight fin efficiency calculator
A straight fin with a fin parameter of 10 per metre and a length of 0.05 m reaches an efficiency of about 0.924, because their product is 0.5.
Free · Runs in your browser
Fixed-fixed beam center load calculator
A 6 m beam fixed at both ends, loaded with 10000 N at midspan, carries 7500 N·m at each support and at the centre, with opposite signs.
Free · Runs in your browser
Flow regime from Reynolds number calculator
A Reynolds number of 3200 falls in the transitional band, between laminar below 2300 and turbulent above 4000.
Free · Runs in your browser
Hydrostatic Force on an Inclined Surface Calculator
A 2.4 m² plate with its centroid 3.5 m below the water surface takes 82.37586 kN of hydrostatic force.
Free · Runs in your browser
Fourier Number Calculator
With a thermal diffusivity of 0.0000117 m²/s, 600 seconds and a characteristic length of 0.05 m, the Fourier number is 2.808.
Free · Runs in your browser
Swamee-Jain friction factor calculator for turbulent pipe flow
Turbulent flow at a Reynolds number of 100000 in a pipe with relative roughness 0.0002 has a Darcy friction factor of 0.018994752725 by the explicit Swamee-Jain…
Free · Runs in your browser
Gear output speed calculator
A shaft turning at 1000 rpm through a gear ratio of 2 drives the output at 500 rpm, a reduction stage.
Free · Runs in your browser
Gear pitch diameter calculator
A spur gear with a module of 2.5 mm and 24 teeth has a pitch diameter of 60 mm. Enter module and tooth count to lay out gear pairs and shaft spacing before the…
Free · Runs in your browser
Pipe pressure drop from head loss calculator
A head loss of 12.5 m of water at 998.2 kg/m³ equals a pressure drop of about 1.2 bar. Enter head loss, density and gravity to get the drop in pascals…
Free · Runs in your browser