One-eighth is bigger than one-twelfth. Both of these figures are fractions and represent parts of a whole. When comparing fractions, if the numerator remains the same, any fraction with a larger denominator is smaller. Twelve is larger than eight, hence, one-eighth is the bigger fraction.

One-eighth represents one part of a whole that consists of eight units, but one-twelfth represents one part of a whole that consists of 12 units. Fractions are made up of numerators and denominators. Numerators are the top numbers and denominators are the bottom numbers. The numerator is the number that represents the part of a whole. The denominator is the total number of parts.