Change your bag every 90 days or when the bag is 75% full. Many vacuum cleaner repairs are a result from not changing the bag on-time. Structurally, Paper vacuum cleaner bags will begin to deteriorate when exposed to dust and dirt after 90 days. Remember every time you turn on your vacuum cleaner air flows in and around the vacuum cleaner bag pushing the bag to its limits. HEPA and charcoal vacuum cleaner bags will do a better job containing the dirt / dust but they have their limitations too.