We recommend using Class 10 or above memory card that is bigger than 16gb in capacity (For 4K video shooting, we recommend using memory cards with >80mb/s write speed). While shooting with JPG-L format and 20-megapixel resolution, each photo will take up Approx. 8mb, which means that a 16gb memory card will be able to hold about 1000 photos. While shooting 4K video, a 4-minute video file will take up Approx. 4gb. Once the limit is reached, video recording will stop automatically (Length limit about 7 minutes and 29 seconds). Therefore we recommend using a memory card with larger storage size for better flexibility.