This site says: Amount of Spouse Benefits
A spouse receives one-half of the retired worker’s full benefits unless the spouse begins collecting benefits before full retirement age. In that case, the amount of spouse benefits is permanently reduced by a percentage based on the number of months before he/she reaches full retirement age.
For example, based on the full retirement age of 65, if a spouse begins collecting benefits:
At 64, the benefit amount would be about 46 percent of the retired worker’s full benefit.
At age 63, it would be about 42 percent and
At age 62, 37.5 percent.
However, if a spouse is taking care of a child who is either under age 16 or disabled and receiving Social Security benefits, a spouse gets one-half of the retired worker’s full benefits, regardless of age.
The official site offers much more information and scenarios, such as:
Social Security survivors benefits can be paid to:
A widow or widower—full benefits at full retirement age, or reduced benefits as early as age 60
A disabled widow or widower—as early as age 50
A widow or widower at any age if he or she takes care of the deceased’s child who is under age 16 or disabled, and receiving Social Security benefits
Unmarried children under 18, or up to age 19 if they are attending high school full time. Under certain circumstances, benefits can be paid to stepchildren, grandchildren, or adopted children.
Children at any age who were disabled before age 22 and remain disabled.
Dependent parents age 62 or older
There are also caculators avaiable so you can estimate just how much you will both get.