Engineering Calculators
Electrical, mechanical, and civil · 10 free tools
Free Engineering Calculators for Students and Professionals
10+ free engineering calculators: Ohm's Law, unit converter, electrical power, gear ratio, RPM, torque, voltage divider, resistor color code, concrete, and pipe flow. Free, no signup, runs in your browser. Use these for lab work, sizing, and preliminary checks.
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All Engineering Calculators
Ohm's Law Calculator
V = IR, find voltage, current, or resistance.
Voltage Divider
Calculate output voltage for a divider.
Electrical Power
Calculate electrical power (P = VI).
Torque Calculator
Torque from force and lever arm.
Concrete Calculator
Calculate concrete volume for slabs.
Pipe Flow Calculator
Flow rate through circular pipe.
Gear Ratio Calculator
Calculate gear ratios and output RPM.
RPM Calculator
Surface speed to RPM conversion.
Resistor Color Code
Resistance from 4-band color code.
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Tips for Using Engineering Calculators
Five practical points worth keeping in mind. First, always check units before reading the result; mixing inches with millimetres or kg with N is the most common source of engineering calculation errors. Second, Ohm's Law assumes a purely resistive DC circuit; for AC circuits with capacitors or inductors you need impedance, not resistance.
Third, gear ratio output torque ignores friction; real systems lose 2 to 10% per stage depending on gear type and quality. Fourth, the concrete calculator returns volume in cubic feet or cubic metres; remember to convert to bag count using the right yield per bag (43 kg cement per bag is standard in India). Fifth, the pipe flow calculator uses simplified Darcy-Weisbach assumptions; real pipes have roughness, bends, and fittings that increase head loss.
Real-World Example
Meet Manish, 22, an electronics engineering student from Indore. His lab assignment is to design a 5V output from a 12V supply using a voltage divider with a 10 mA load. Using the voltage divider calculator, he tries R1 = 700 ohm and R2 = 500 ohm. The tool returns Vout = 5V with no load, but he then computes the loaded output using a parallel combination of R2 and the load resistor.
He realises the divider current must be at least 10 times the load current for the 5V rail to hold under load. He sets the divider current to 100 mA, picks R1 = 70 ohm and R2 = 50 ohm, and confirms the calculator output. Power dissipation in R1 is checked using the electrical power calculator: 0.7W. He moves on to selecting a 1W rated resistor for safety margin. The whole exercise took 10 minutes instead of an hour with manual calculation.
A Note on Safety-Critical Use
Engineering calculators here are for learning, homework, and preliminary estimation. They are not a substitute for licensed engineering analysis on any project where safety, regulatory compliance, or significant cost is involved. Load calculations for structural members, electrical specifications for installations, and fluid systems for industrial use all require verification by a licensed engineer using proper codes and safety factors.
For questions or new engineering calculator requests, write to allsmartcalculators@gmail.com. Specific topic suggestions like 3-phase power, transformer sizing, or beam deflection are welcome.