Goods are perfect complements for the consumer if he or she always wants to consume these goods in fixed proportions, for example

- right shoes are always consumed one-to-one with left shoes.

- cars and tires are consumed in fixed proportions of one to four

- If consumption and leisure are perfect complements => the consumer always wants to have C/l = constant => C = al where a >0 - The indifference curves of the consumer are L-shaped, with the right angles of the indifference curves falling along the line C = al