A typical Funeral or Memorial service is around 1 to 1-1/2 hours long.  If you add a reception or meal at the location, you should plan an additional 2 hours.  If you are planning to use a rented facility, you will want to keep in mind their cost for rental charges.
A graveside or niche-side service is usually no longer than 30 to 45 minutes long. The exception to this is a National Cemetery Committal where every family is allowed no more than 25 minutes from the time we arrive at the shelter where the service is to take place. This includes time for Honors for a Veteran. The National Cemeteries maintain a strict schedule due to the number of committal services that are conducted each day.
If your loved one will be laid to rest at a National Cemetery, you may want to consider a gathering after the Committal to allow people more time to share their memories in a more relaxed setting. Heritage Oaks Memorial Chapel is available as an option. Catering can be arranged to take this added responsibility off your shoulders and give you the opportunity to give your full attention to the Committal.