In North America, Special K Original has 110 Cal per 29 g cup serving. One serving contains 0.5 g fat, 22 g carbohydrates, 2 g sugar and 5 g protein. In the UK, Special K Original is 17% sugar, meaning a 30g serving contains 5g of sugar.

In the UK, a recent advertising campaign has focused on the results of a study run in collaboration with the Department of Human Sciences at Loughborough University requiring overweight volunteer subjects to replace two meals a day with a bowl of the cereal. The study found that "after 2 weeks up to 75% of subjects had slimmer waists and hips. The university's scientists concluded that the majority of this was due to fat loss."

In the US, Special K currently comes in nine different varieties:

In the UK, Special K currently comes in ten varieties:

Special K bars are marketed as a low fat snack alternatives to regular snacks. There are several varieties of Kellogg's Special K bar, including original, apple & pear, blueberry, chocolate, orange & chocolate, raspberry & chocolate, peach & apricot. There are new flavors that were created such as cherry, watermelon and pineapple.

Special K Mini Breaks are a low-fat bite-size snack. They come in the following flavours:

Rice, wheat gluten, sugar, defatted wheat germ, salt, high fructose corn syrup, dried whey, malt flavoring, calcium caseinate, ascorbic acid (vitamin C), alpha tocopherol acetate (vitamin E), reduced iron, niacinamide, pyridoxine hydrochloride (vitamin B6), riboflavin (vitamin B2), thiamin hydrochloride (vitamin B1), vitamin A palmitate, folic acid, and vitamin B12.

Special K's original formula is different in Canada compared to the US. The Canadian formula has a different tasting flake which reflects the "Canadian taste preference" (according to the Consumer Relations department of Kellogg's in Canada) while the American formula is like the other related products but without nuts or dried fruits.

The Canadian formula includes rice, wheat gluten, sugar/glucose-fructose, defatted wheat germ, salt, malt (corn flour, malted barley), vitamins (thiamin hydrochloride, niacinamide, pyridoxine hydrochloride, folic acid, d-calcium pantothenate), iron, and BHT added to the package material to maintain product freshness.

Rice, wheat (wholewheat, wheat flour), sugar, wheat gluten, defatted wheatgerm, dried skimmed milk, salt, barley malt flavouring, vitamin C, niacin, iron, vitamin B6, riboflavin (B2), thiamin (B1), folic acid, vitamin D, vitamin B12.