The most direct answer is found in 1 Corinthians 11: 5-6: But every woman who [publicly] prays or prophesies, [teaches, reproves, comforts] when she is bareheaded dishonors her head [her husband]; it is the same as [if her head were] shaved. (6) For if the woman will not wear [a head] covering, then she should cut off her hair too"  Amplified Bible.  We understand that this standard applies to female adult followers of Christ as their Redeemer and Lord, attending public meetings of the church. 

The apostle Paul explains earlier in 1 Corinthians 11:3 the reason for a woman to wear a head covering: "the head of every man is Christ; and the head of the woman is the man; and the head of Christ is God."   The proper order is: God, Christ, man, woman.  The covering on the woman's head shows that the man is the head of the woman, just as Christ is the head of the man, and God is the head of Christ.  We would suggest that if you understand and appreciate what the covering represents in God's arrangement –the order and place of the woman in the church – then you should consider wearing a head covering.  Wearing a head covering would be a privilege more than a rule or custom.  Your conscience will guide you.