For outdoor projectors, the number of lumens needed depends on various factors such as ambient light conditions and screen size. Generally, a minimum of 2000 lumens is recommended for outdoor viewing during dusk or twilight. If the outdoor viewing is during the day or under bright sunlight, you may need a projector with a higher lumen count, such as 3000 lumens or more, to ensure a bright and clear image. Additionally, if you plan on projecting onto a larger screen, you may also need a higher lumen count to maintain image quality. It's important to consider these factors when choosing the right outdoor projector to ensure optimal viewing experience.