Sodium to Salt Conversion on Food Labels: The 2.5× Rule Explained

Why table salt (sodium chloride) weighs 2.5 times as much as its sodium content

As the U.S. Food and Drug Administration (FDA) explains in its guide to Sodium in Your Diet, the words "table salt" and "sodium" are often used interchangeably in everyday conversation, but they do not mean the same thing. Table salt—known chemically as sodium chloride (NaCl)—is a crystal compound made of two elements: sodium and chloride.

By atomic weight, sodium makes up roughly 40% of the sodium chloride molecule and chloride makes up the remaining 60%. Therefore, every 1 gram (1,000 mg) of sodium corresponds to approximately 2.5 grams of table salt. As Oregon State University's Linus Pauling Institute notes, the National Academy of Medicine's adult Adequate Intake (AI) of 1.5 g/day of sodium equals about 3.8 g/day of salt (sodium chloride), and the Chronic Disease Risk Reduction (CDRR) / FDA Daily Value limit of 2.3 g/day (2,300 mg/day) of sodium equals about 5.8 g/day of salt—roughly 1 level teaspoon of table salt, which matches the UK National Health Service (NHS) adult maximum recommendation of no more than 6 g of salt a day.

• 400 mg sodium (0.4 g sodium) ≈ 1.0 g salt
• 1,000 mg sodium (1.0 g sodium) ≈ 2.5 g salt
• 1,500 mg sodium (1.5 g sodium, adult Adequate Intake) ≈ 3.8 g salt
• 2,300 mg sodium (2.3 g sodium, FDA Daily Value limit) ≈ 5.8 g salt (about 1 level teaspoon of table salt; UK NHS limit is 6 g salt)

How to convert between mg of sodium and grams of salt in seconds

Whether you are logging an imported chutney or bread label that lists "Salt (g)" into a U.S. tracker that expects "Sodium (mg)", or translating a U.S. label into grams of salt, use the 2.5 conversion factor:

1. From Sodium (mg) to Salt (g): Divide milligrams of sodium by 1,000 to get grams of sodium, then multiply by 2.5 (or simply divide mg of sodium by 400). Hypothetical math example: A soup serving with 800 mg of sodium contains 800 ÷ 400 = 2.0 g of salt.
2. From Salt (g) to Sodium (mg): Multiply grams of salt by 400 (which is dividing by 2.5 and multiplying by 1,000). Hypothetical math example: An imported flatbread listing 1.2 g of salt per 100 g contains 1.2 × 400 = 480 mg of sodium per 100 g.

Why a food can contain sodium even without added table salt

According to the FDA, over 70% of dietary sodium in the United States comes from packaged and prepared foods rather than the salt shaker at the table (the NHS similarly reports that around three-quarters of salt intake in the UK comes from everyday packaged foods like bread, breakfast cereals and ready meals).

In addition to sodium chloride, the FDA notes that several common kitchen and commercial ingredients contribute sodium to the total "Sodium" figure on a Nutrition Facts panel even when a dish does not taste overtly salty—most notably sodium bicarbonate (baking soda, used in flatbreads, batters and baked goods), monosodium glutamate (MSG) and sodium benzoate.

Sources & Classical References

1. FDA: Sodium in Your Diet — Use the Nutrition Facts Label and Reduce Your Intake — Explains the difference between table salt (sodium chloride) and sodium, the 2,300 mg Daily Value (~1 teaspoon of table salt), non-salt sodium ingredients like baking soda (sodium bicarbonate), and why over 70% of sodium comes from packaged foods.
2. Linus Pauling Institute, Oregon State University: Sodium (Chloride) — Documents the equivalence between sodium and sodium chloride (salt) intakes: 1.5 g/day sodium = 3.8 g/day salt (AI) and 2.3 g/day sodium = 5.8 g/day salt (CDRR).
3. UK National Health Service (NHS): Salt in your diet — Provides the UK recommendation of no more than 6 g of salt a day (around 1 level teaspoon) for adults and explains how salt is listed on UK food labels.