Minecraft wiki entry for Lava, associated text: In the Overworld and the End, lava travels 3 blocks in any horizontal direction from a source block. Lava flows far more slowly than water (1 block every 30 game ticks, or 1.5 seconds), and sourceless lava flows linger for a short time more. In the Nether, lava travels 7 blocks horizontally and spreads 1 block every 10 game ticks, or 2 blocks per second, which is half the speed as water in the Overworld. In all dimensions, lava spreading uses the same mechanic as water: for every adjacent block it can flow into it tries to find a way down that is reachable in four or fewer blocks from the block it wants to flow to. When found, the flow weight for that direction is set to the shortest path distance to the way down. (This can result in lava flows turning toward dropoffs that they cannot reach in the Overworld and the End.)