Enter any two values. Leave the other two blank — they will be calculated for you.
Enter resistor values separated by commas (e.g. 100, 220, 470).
Enter a target resistance — get the nearest E12 and E24 standard values.
Calculate the resistor needed when wiring LEDs in series from a shared supply.
Find the output voltage from a two-resistor divider, or find R2 for a target Vout.
Give a known Vin, R1, and your required output voltage — get the R2 value you need.
Estimate the DC resistance of a PCB trace and the voltage drop at a given current.
Or convert dB back to a linear ratio:
Inductor reactance (XL = 2π × f × L):
Estimate how long a battery will power a circuit at a given current draw.
Find the minimum power supply rating needed for your circuit, with a safety margin.
Convert battery capacity to Watt-hours and find charge time from a given charger current.
Find the −3 dB cutoff frequency for a first-order RC filter, or find the component value needed for a target frequency.
Calculate the resonant (tank) frequency of an LC circuit, or find L or C for a target frequency.
Calculate the output frequency and duty cycle of a 555 timer in astable mode.
Look up diameter, area, resistance, and current capacity for any AWG gauge wire.
Calculate the total DC resistance of a wire run and the voltage drop at your load current.
Enter your required current and get the recommended minimum AWG gauge for chassis wiring.
Calculate the series resistor needed to bias a Zener diode regulator and verify power ratings for both components.
Check worst-case power dissipation in the Zener diode when load is disconnected (maximum Zener stress condition).
Select a standard Zener voltage to see its E24 series part numbers, typical power ratings, and tolerance.
Calculate turns ratio, secondary voltage or current from primary parameters. Works for step-up and step-down transformers.
Find the minimum VA rating needed for your transformer given load power, power factor, and a safety margin.
Estimate the DC output voltage after a rectifier and filter capacitor from a transformer secondary voltage.
Calculate gain, output voltage, and bandwidth for an inverting op-amp amplifier configuration.
Calculate gain, output voltage, and bandwidth for a non-inverting op-amp amplifier configuration.
Differential amp: Vout = (Rf/R1) × (V2 − V1). Summing amp: Vout = −Rf × (V1/R1 + V2/R2).
One free technology calculator covering Ohm's law, resistor color codes, LED resistors, voltage dividers, RC time constants, PCB trace width, Zener diodes, transformers, op-amp gain, battery runtime, filter design, wire gauge, and more — runs entirely in your browser, no login needed.
Every tool runs instantly in your browser. From basic electronics to advanced circuit design — all in one place, no login required.
Enter any two of voltage, current, resistance, or power — the other two are solved instantly. Results show all four values with formulas, helping you cross-check component ratings and verify designs.
Interactive 4-band and 5-band color code decoder with live resistor body preview. Shows resistance, tolerance, min/max values. Also finds the nearest E12 and E24 standard value for any target resistance.
Preset forward voltages for red, orange, yellow, green, blue, white, and IR LEDs. Results include exact resistance, nearest E12 value, power dissipated, and voltage across the resistor. Series LED string supported.
Solve Vout from R1/R2, or find the R2 needed for a target Vout. Results show output voltage, divider ratio as percentage, and current through the resistor string.
Calculate τ = R × C and see times to reach 63% (1τ), 95% (3τ), and 99.3% (5τ). Also shows the filter cutoff frequency and capacitor energy/charge storage.
Minimum trace width for any current and temperature rise on inner or outer copper layers. Also calculates DC resistance and voltage drop for a real trace by length, width, and copper weight.
Calculate the series resistor for a Zener voltage regulator, verify power dissipation in worst-case (no load) conditions, and look up standard Zener voltages with part codes and power ratings.
Find turns ratio, secondary turns, primary current, and output power with efficiency correction. Also calculates minimum VA rating for your load and estimated DC output after a rectifier and filter stage.
Inverting and non-inverting amplifier gain, output voltage, and bandwidth limit from GBW product. Also covers differential and summing amplifier configurations with instant Vout results.
RC low-pass/high-pass cutoff (solve for fc, R, or C). LC resonant frequency. 555 astable oscillator: frequency, duty cycle, and high/low period times from R1, R2, C.
Battery runtime with efficiency adjustment. mAh to Watt-hours, charge time, and C-rate. Power supply sizing with configurable safety margin, minimum current rating, and power loss budget.
AWG wire diameter, resistance per metre, and max current for gauges 0–30. Voltage drop along a wire run with round-trip option. Minimum AWG recommendation for any current and application type.
A technology calculator should cover the real problems engineers face every day — not just a single formula, but a full set of interconnected tools that work together. This page brings together the most commonly needed electronics and hardware calculations: from the basics of Ohm's law and resistor color codes through to Zener diode regulation, transformer design, op-amp gain, PCB trace sizing, and wire gauge selection.
The Zener tab calculates the series resistor needed to bias a Zener regulator at a given load current, then checks worst-case power dissipation when the load is removed — the condition where the Zener absorbs the most current. The Transformer tab covers turns ratio, secondary current, efficiency-corrected output power, minimum VA rating, and estimated DC output voltage after a bridge rectifier. The Op-Amp tab handles inverting amplifiers (gain = −Rf ÷ Rin), non-inverting amplifiers (gain = 1 + Rf ÷ R1), and differential and summing configurations — all with GBW-limited bandwidth calculation.
The Ohm's Law tab solves any two of V, I, R, P when you give it the other two — showing all four values together. The Resistor tab decodes 4-band and 5-band color codes with a live visual preview of the resistor body, and also finds the nearest E12 and E24 standard value for any target resistance. The LED tab calculates the series resistor needed for any LED color with presets for red, orange, yellow, green, blue, white, and IR. The Voltage Divider works both ways: find Vout from R1 and R2, or find R2 needed for a target Vout.
The PCB Trace tab applies the IPC-2221 formula for minimum trace width at any current and allowed temperature rise, for inner or outer copper layers, and also estimates the DC resistance and voltage drop of a real trace by length and width. The RC tab gives the time constant τ = R × C with 1τ, 3τ, and 5τ milestones and the filter −3 dB cutoff frequency. The Battery tab estimates runtime using efficiency-adjusted capacity, and converts between mAh, Watt-hours, and charge time. The Wire / AWG tab looks up every standard gauge from AWG 0 to AWG 30 and recommends the minimum gauge for any current requirement with application-specific derating.
This Technology Calculator tool is designed for electronics calculations like resistor values, LED setup, and voltage divider, helping users build circuits more easily. It saves time and reduces errors. You can also connect it with Engineering Unit Conversion calculator, use Download Time Calculator tool, and Programmer Calculator online for full technical support.
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