Maker's Bench

A compact electronics workbench for quick calculations. Inputs stay in this browser; the calculators do not send them.

Choose a calculator — Pilot A / five tools

Ohm's Law Enter any two of voltage, current, resistance, and power.

Enter two positive values. Leave a field blank or set it to zero to clear it.

V Voltage [V]

I Current [A]

R Resistance [Ω]

P Power [W]

LED Series Resistor Estimate a current-limiting resistor and a power rating.

Supply voltage, Vs [V]

LED forward voltage, Vf [V]

Target current, If [mA]

The E12 recommendation is the smallest supported value at or above the calculated resistance, so the estimated current does not exceed the target.

Resistor Color Code Convert values to bands or bands to values; supports four-band and five-band codes.

Resistance [Ω]

Tolerance

555 Astable Estimate frequency, period, and output duty cycle from R1, R2, and C.

R1 [Ω]

R2 [Ω]

C [µF]

This is an ideal estimate for the classic 555 astable circuit. Component tolerances and timer characteristics affect the actual output.

Battery Life Estimate runtime from capacity and average current.

Capacity [mAh]

Average current [mA]

Theoretical estimate. Real battery runtime has not been physically validated by this calculator. Actual runtime varies with battery chemistry, discharge characteristics, load variation, temperature, battery age, converter efficiency, and cutoff voltage. No generic correction factor is applied.