ffmpeg example
/* In this example each image will have a duration of 5 seconds (the inverse of 1/5 frames per second). */
ffmpeg -framerate 1/5 -i img%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4
Alternatively, choose an online converter. There are a couple of neat websites for this, see the Google search [Link].