Gas mark 4 in an electric fan oven is equivalent to 160 degrees Celsius or 320 degrees Fahrenheit. It is important to note that fan oven temperatures are typically around 20°C less than conventional ovens because the fan circulates hot air around the inside of the oven and into the food, ensuring a more even temperature and food thats cooked more quickly. When converting oven temperatures, it is always best to use a conversion chart to ensure accuracy.