Calculators
Planning tools for radio history & electronics hobbies, with visible assumptions and units.
Estimate the nominal capacity and stored energy of batteries connected in parallel. Enter each battery's capacity and nominal voltage. The calculation assumes compatible batteries at the same voltage and sums their ratings without accounting for age, temperature, wiring losses, or discharge limits.
Estimate a battery pack’s nominal voltage by adding the voltage contributions of cells connected in series. Enter the nominal voltage and count for each cell group. This calculator does not estimate loaded voltage, capacity, runtime, or charging requirements.
Add the capacitance values of capacitors connected in parallel to find their ideal total capacitance. Enter each capacitor value in microfarads (µF).
Calculate the equivalent capacitance of capacitors connected in series using each capacitor's value in microfarads (µF).
Estimate the parts cost of a hobby circuit build from component quantities and unit prices, plus an optional shipping allowance. Enter prices in your chosen currency. This estimates listed parts and shipping only; it excludes taxes, tools, and labor.
Calculate electrical power in watts from voltage and current using the direct-current relationship P = V × I. Enter voltage in volts and current in amperes.
Estimate a hobby electronics project's total budget from parts, tools, shipping, and a user-selected contingency allowance.
Convert a radio frequency into its free-space wavelength using the speed of light. Enter frequency in hertz and choose a practical output unit.
Calculate the ideal resonant frequency of an LC circuit from its inductance and capacitance. Enter component values and select their units to get the frequency in hertz.
Calculate the ideal series resistance for one LED from the supply voltage, LED forward voltage, and target current. The result is theoretical and does not select a resistor rating or account for component tolerances.
Calculate electrical voltage in a simple resistive circuit by multiplying the supplied current by resistance. This tool demonstrates Ohm's law and does not assess component safety or circuit performance.
Calculate the equivalent resistance of three resistors connected in parallel using their resistance values in ohms.
Estimate the number of identical parts that fit in a bin by dividing usable bin volume by the volume of one part. This volume-based estimate assumes the parts can be packed without gaps; actual capacity depends on shape and arrangement.
Convert a radio frequency value between hertz, kilohertz, megahertz, and gigahertz using exact metric scale factors.
Estimate the electricity cost of listening to a radio over a chosen period using its power draw, listening time, and your electricity rate. The estimate assumes the radio draws the stated power whenever it is on.
Calculate the time constant of a resistor-capacitor circuit from resistance and capacitance. The result is the time required for a first-order RC circuit to complete about 63.2% of its total voltage change during charging or discharging.
Decode a conventional four-band resistor using two significant-digit bands, a multiplier and one of four listed tolerance bands. The output is the lower-to-upper resistance interval in ohms, not a power or voltage rating.
Calculate the total resistance of resistors connected in series by adding their resistance values. Enter each resistor in ohms.
Calculate the ideal output voltage of a two-resistor voltage divider from the supply voltage and resistor values. Assumes an unloaded output and ideal components.
Estimate the top surface area of a rectangular workbench from its length and width. Enter both measurements in inches to get the area in square feet and square inches.