Engineering Calculators: Electrical, HVAC & Mechanical

Engineering calculator library

Check electrical, mechanical, structural and energy calculations in one place.

Browse 25 tools, including electrical power, wire sizing, HVAC, beam loads and solar planning. Each result depends on the units, inputs and assumptions you choose; verify safety-critical work against the applicable code and professional design.

25tools including related utilities

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Showing 25 of 25 tools

Featured

8 tools

Start with core electrical, flow, cooling and solar sizing calculations.

Ohm's Law CalculatorSolve voltage, current, resistance and electrical power from two known values. Resistor Color Code CalculatorRead four-, five- and six-band resistors or find bands for a value. Voltage Drop CalculatorEstimate conductor voltage loss from current, length and size. Wire Gauge CalculatorCompare conductor sizing by ampacity and voltage drop. Flow Rate CalculatorCalculate volumetric and mass flow from pipe size and velocity. AC Sizing CalculatorEstimate cooling capacity with room, sun and ceiling adjustments. BTU CalculatorEstimate heating or cooling load from room and insulation inputs. Solar Panel Size CalculatorPlan an array from daily energy use, sunlight and system losses.

Electrical & electronics

5 tools

Work with power, circuits, components and acoustic enclosure estimates.

Watt CalculatorCalculate AC or DC power, volts, amps, energy use and electricity cost. Capacitor CalculatorCalculate series or parallel capacitance, stored energy and time constants. LED Resistor CalculatorChoose a series resistor and check its power dissipation. Power Factor CalculatorCompare real, reactive and apparent power and a correction target. Speaker Enclosure CalculatorEstimate sealed or ported speaker boxes from driver parameters.

Mechanical

5 tools

Check density, mass, rotation, gear ratios and torque.

Density CalculatorSolve mass, volume or density from the other two values. Gear Ratio CalculatorEstimate gear ratio, output speed and torque multiplication. Horsepower CalculatorConvert horsepower units or calculate power from torque and RPM. Material Weight CalculatorEstimate material weight from dimensions and density. Torque CalculatorCalculate rotational moment from force, radius and angle.

Civil & structural

2 tools

Estimate beam reactions and movement for the supported load cases.

Beam Deflection CalculatorEstimate deflection, moment and shear for selected support cases. Beam Load CalculatorCalculate reactions, bending moment and deflection for common loads.

HVAC, energy & solar

2 tools

Compare cooling loads, solar generation and financial scenarios.

Solar Panel Payback CalculatorEstimate solar payback using system cost, production and rates. Solar Savings CalculatorProject annual electricity savings against current usage and rates.

Technical utilities

1 tool

Estimate the material and machine cost of a 3D print.

3D Printing Cost CalculatorEstimate print material, electricity and machine-time cost.

From input to specification

Use an estimate as a checkable step

Identify the system

Confirm DC, single-phase or three-phase power, the supported load case, and whether the tool expects metric or imperial inputs.

Check the assumptions

Review power factor, conductor length, beam supports, thermal conditions or solar losses. Change the inputs to see how sensitive the result is.

Verify the design

For installation or construction, apply the governing code, safety factors and manufacturer specifications with a qualified professional.

Why current capacity and voltage drop are separate checks

A wire can carry a current without overheating yet still lose too much voltage over a long run. Use the Wire Gauge Calculator for a preliminary conductor estimate and the Voltage Drop Calculator to review the run length. The Watt Calculator helps determine electrical power and current from known values. These figures do not replace derating, protection or installation rules in the code applicable to your project.

Frequently asked questions

Quick answers about units, power and the limits of a planning estimate.

Can I use these results for a real installation?

Use them for preliminary planning and checking. Final electrical, structural and mechanical specifications must meet the relevant local code and be reviewed by a qualified professional.

Why does an AC sizing estimate seem large?

Rule-of-thumb room inputs can miss window orientation, insulation, infiltration and internal gains. A full load calculation is needed before selecting equipment; an oversized unit can perform poorly.

What is the difference between real, reactive and apparent power?

Real power is measured in watts, apparent power in volt-amperes, and reactive power in VAR. Power factor relates real power to apparent power in an AC circuit.

What is the difference between watts and kilowatt-hours?

Watts measure power. Kilowatt-hours measure energy used over time: a 1 kW load running for 3 hours consumes 3 kWh.

Which units should I enter?

Read the unit next to each field and select the matching measurement system. Check whether an input is line-to-line voltage, length in one or two directions, or a value converted from another source.

Do solar estimates include every future change?

Check the assumptions on the individual solar tool, including system losses, rates and time horizon. Future weather, pricing, maintenance and panel output can differ from an estimate.

Continue with a connected calculation.

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