1 y (yocto) is equal to 0.000000000000000000000000000000000000000000001 Z (zetta). To convert from yocto to zetta, multiply by 0.000000000000000000000000000000000000000000001 or divide by 1,000,000,000,000,000,100,000,000,000,000,000,000,000,000,000.