555 Timer Calculator

Find the frequency and duty cycle of an astable 555 timer.

Frequency (Hz) 68.571

Duty cycle (%) 52.381

Formula: f = 1.44 ÷ ((R₁ + 2R₂)·C)

Step-by-step with your numbers:

1. Values used:

2. R₁ = 1,000 Ω

3. R₂ = 10,000 Ω

4. Capacitance = 1 µF

6. Frequency = 68.571Hz

7. Duty cycle = 52.381%

Did we solve your problem today?

The 555 timer in astable mode generates a continuous square-wave oscillation.

The math behind it

f = 1.44 ÷ ((R₁ + 2R₂)·C). Duty cycle = (R₁ + R₂) ÷ (R₁ + 2R₂).

R₁ = 1 kΩ, R₂ = 10 kΩ, C = 1 µF → about 68.6 Hz, 52% duty.

Why can't duty go below 50%?

In the standard astable circuit the charge path is always longer; a diode mod fixes this.