The formulas to calculate the time high and time low for the timer are as follows (typically):
Time HIGH (seconds)

Time LOW (seconds)

$$x = {0.693(R_1 + R_2) * C_1}$$

$$x = {0.693(R_2 * C_1)}$$

You can use the calculator below to calculate these values as well as frequency and duty cycle.
Results:
Frequency

0.000

Hz

Duty Cycle

0.000

%

Time HIGH

0.000

s

Time LOW

0.000

s

Schematic:
