Read a Label in 30 Seconds

An ordered procedure: serving size, sodium line, per-100 g comparison, decision — with the mistakes that derail it.

Nutrition labels list sodium in milligrams per serving, and the servings per package decide the real total. The routine below turns those two lines into a decision in about half a minute.

Step one: find the serving size. Every sodium figure on the label refers to this portion, not to the package. If the serving is 30 g and you plan to eat 90 g, triple every number you read from that point on.

Step two: locate the sodium line. It is stated in milligrams. Compare it directly against the 2000 mg WHO limit: a figure of 500 mg is a quarter of the day's budget, 1000 mg is half.

Step three: convert to a per-100 g comparison. Divide the sodium figure by the serving size in grams and multiply by 100. This lets you compare two brands whose serving sizes differ, which is where most shoppers go wrong.

Step four: decide. If one serving consumes a large share of the 2000 mg budget and you will eat more than one serving, put it back or plan the rest of the day around it. The typical failure is skipping step three: comparing two labels whose serving sizes differ by a factor of two.

In typical industrialised diets the majority of sodium comes from processed and restaurant food, so this routine applied at the supermarket is the single highest-leverage habit for staying under the limit.

• Typical failure 1: reading the per-serving figure without checking servings per package.
• Typical failure 2: comparing two brands without normalising to per-100 g.
• Typical failure 3: treating the label figure as covering the whole package.

Further reading

• The 2000 mg Limit in Real Food
• Swaps That Cut Sodium in Half