IC 555 Timer Calculator

R1: R K M
R2: R K M
C:     uF nF pF

T₁ Output High (Seconds) =
T₂ Output Low (Seconds) =
T Total Period (Seconds) =
Frequency (Hz) =
Duty (%High) =

T₁ = 0.7(R₁ + R₂)C and T₂ = 0.7 R₁ C

So T = 0.7 (R₁ + 2R₂)C or f = 1.45/((R₁ + 2R₂)C)

Where T₁ = High Period, T₂ = Low Period,T = Total Period, f = Frequency.

R: R K M
C:   uF nF pF

T Output High (Seconds) =