Adjustments for sea-level cake recipes at 5,000 feet/1524 meters
- Reduce baking powder, baking soda by 50 percent.
- Reduce sugar by 2-1/2 tablespoons per cup.
- For each cup of liquid, add another 3 tablespoons of liquid (or an egg)
- Increase flour by 2 tablespoons
- Increase baking temperature by 15° F (10° C).*
* Other sources say a rule of thumb is to increase the temperature by up to 10 percent (so a recipe calling for baking at 350° F would be adjusted to about 385° F). Remember to check the oven a little earlier than the recipe specifies whenever you increase baking temperatures.
Here's the link to my slides for my IgniteBoulder presentation on this topic.