555 Astable Calculator

555 Astable Calculator

Use this calculator to find out the time period, capacitor, or resistor values needed to make a 555 astable oscillator.

Be careful when calculating for the passives, as some combinations are physically impossible (you will get negative resistances)!

Solve For:
C1
R1
R2
Result Ready!
Frequency N/A
Duty Cycle N/A
On Time N/A
Off Time N/A

T = 0.693 \times C_1 \times (R_1 + 2 R_2)