If you have to go with just one ratio for fertilizer for centipede grass and don’t want to do a soil sample this is the way to go.
You can almost always get away with 15-0-15 centipede grass fertilizer with added iron (ferrous) sulfate at a mild rate of 2 pounds per 1000 square feet. Using that low amount per sq ft of centipede grass fertilizer will be less likely to do any damage and still feed your lawn. You can go back three weeks later and add the same dosage to your lawn if it is doing slightly better but not responding as fast as you would like.
There are quite a few different brands of lawn fertilizer on the market. If you want to keep your cost down Centipede lawns do well with a generic mix of fertilizer such as 16-4-8. Just keep that middle number (Phosphorus) as low as possible. Centipede grass needs very little Phosphorus to grow well. 16-4-8 fertilizer can be applied at a rate of 3 pounds per 1000 square feet each feeding.
If you use a generic fertilizer spraying with iron (ferrous) sulfate (2 ounces in 5 gallons of water for every 1,000 square feet) will help to enhance a darker green lawn color.
Keep in mind that it is best to get a soil test. The proper amount of fertilizer to apply can be determined by a soil test.