How many levels does an eevee have to be to evolve into an espeon or an umbreon?

Eevee evolves into Espeon when it reaches at least level 15 with high friendship during the daytime. For Umbreon, Eevee must also be at least level 15 but evolves when it has high friendship during the nighttime. Therefore, both evolutions require Eevee to be at least level 15.