A transistor is an electronic faucet: a trickle at the base controls a flood at the collector. In its amplifying region, the collector current equals the current gain beta times the base current, I_C = β × I_B. A small-signal transistor with β = 200 turns 0.1 mA at the base into 20 mA at the collector — enough to light an LED brightly from a whisper of control current, which is the entire basis of electronic switching and amplification.

This calculator runs the gain multiplication. Type the transistor's current gain β (hFE) from its datasheet into Variable A and the base current in amps into Variable B; the Result box gives the collector current in amps. An Arduino hobbyist in Colorado driving a 12-volt LED strip, for instance, enters β = 100 in Variable A and 0.005 (5 mA) in Variable B, reading 0.5 A of switching capacity — plenty for the strip, with margin to spare. Real designs then add a base resistor to set that current deliberately, and check the transistor's maximum ratings so the faucet never bursts its pipes.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Transistor Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.