• Use a colon to separate hour from minutes. The colon and minutes are not necessary for even-hour times.

3:30 p.m.
11 a.m. (not 11:00 or 11:00 a.m.)

• In listings, use the following model to specify a time range:

5:30–8:30 p.m. (note the en dash)
10 a.m.–1:30 p.m. (note the en dash)

•  In text, use the following model to specify a time range:

from 5:30 to 8:30 p.m. (not from 5:30–8:30 p.m.)
from 10 a.m. to 1:30 p.m. (not from 10 a.m.–1:30 p.m.)

• Use noon and midnight, not 12 noon or 12 a.m., or 12 midnight or 12 p.m. In formal invitations, you may elect to use the following model:

six-thirty
seven-fifteen
eight o’clock

• See also en dash.