How long do febrile convulsions usually last for ?

Usually < 5 min: They usually last only for a few seconds and almost always last less than 15 minutes.

Age 6 mos to 6 yrs: Febrile seizures occur in 4% of children 6 months to 6 years. Each seizure usually are brief, a few seconds to a few minutes.

Febrile convulsion: Simple febrile convulsions does not usually last long. It may only be a few seconds and it is unusual for it to last more than five minutes. The child may be sleepy for some minutes afterwards.