Read the two lines above sodium first

Every Nutrition Facts label begins with servings per container and serving size. The serving size appears as a household measure suited to the food, such as a cup, a tablespoon, a piece, a slice, or a jar, followed by the weight in grams. Both parts matter, and the gram figure is the one that makes honest comparison possible.

Household measures vary between products in ways that look harmless. One cracker label says 5 crackers, another says 4 crackers, and a third says 1 ounce. One pasta sauce says half a cup, another says a third of a cup. The gram weight beside the household measure is the common currency, because 30 grams of one product is the same quantity of food as 30 grams of another.

The serving size is also not advice. The FDA states plainly that by law serving sizes reflect the amount people typically consume, not how much anyone should eat, and that the serving size is not a recommendation. Treat it as a measuring unit for comparison, nothing more. A separate article in this series looks at serving size in more depth, including why the reference amounts were updated using more recent eating data.

A three step comparison that settles most cases

Here is the sequence that works for nearly any two products in the same category.

1. 1 Compare the serving sizes in grams or milliliters. If both labels use the same weight, the comparison is direct and you can move on. If they differ by more than a few grams, you will need the per 100 grams step below.
2. 2 Compare sodium in milligrams for that equal amount. This is the decisive number. A difference of 200 mg per serving on a food you buy every week is a real difference.
3. 3 Check the percent Daily Value as a sanity test. It should point the same direction as the milligrams. If it does not, one of the serving sizes is not what you thought.

Then add one more question that people skip: how many servings are in each container, and how much of the container will you actually eat. That question sometimes reverses the answer, as the soup example further down shows.

When the serving sizes do not match

Unequal servings are common between brands, and the fix is a single calculation. Divide the sodium by the grams in the serving, then multiply by 100. That gives sodium per 100 grams, a figure that puts any two foods on the same footing.

Suppose Brand A crackers list 230 mg of sodium in a 28 gram serving and Brand B lists 240 mg in a 31 gram serving. Brand A looks lower. Run the math and Brand A comes to about 820 mg per 100 grams while Brand B comes to about 775 mg. Brand B is the lower sodium product per bite, and the label numbers alone pointed the wrong way.

For liquids, do the same thing with milliliters. For foods sold by the ounce, an ounce is about 28 grams, so per ounce comparisons work too as long as you use the same unit on both labels. If mental math in the store feels like too much, the phone in your pocket handles it in seconds, and you only need to do it once per product because the answer stays useful until the recipe changes.

One caution when you compare a dry mix with a ready to eat food. Some labels describe the product as packaged and others describe it as prepared, which assumes the water, milk, butter, or oil the directions call for. Condensed soups and boxed side dishes often use the prepared column. Compare as prepared with as prepared, or you will credit the dry mix with sodium it will gain in your kitchen.

What percent daily value adds, and what it hides

The percent Daily Value tells you what share of a day's reference amount one serving supplies. For sodium, the Daily Value on the label is less than 2,300 mg per day, which is also the limit the Dietary Guidelines for Americans, 2025 to 2030 give for everyone age 14 and older. Because the reference is 2,300 mg, each 1 percent of Daily Value equals 23 mg. That single fact turns percent DV into milligrams and back whenever you need it.

The FDA offers a rule of thumb worth memorizing: 5 percent Daily Value or less per serving is considered low, and 20 percent or more is considered high. In milligrams, 5 percent is about 115 mg and 20 percent is about 460 mg. Anything at or above roughly 460 mg in a single serving deserves a second look, whatever the front of the package says.

Percent DV is best used as a fast sort rather than a tiebreaker. Labels round the percentage to whole numbers, so two products showing 15 percent could be 40 mg apart. Use the percentage to separate the low sodium options from the high ones, then let the milligrams decide between close finishers.

If your own target is lower than 2,300 mg, the percentages still work with one adjustment. The American Heart Association recommends no more than 2,300 mg a day and describes an optimal goal of no more than 1,500 mg a day for most adults. Against a 1,500 mg target, multiply the label percentage by about 1.5. A serving marked 20 percent of the Daily Value is closer to 31 percent of 1,500 mg. Whether a lower personal target makes sense for you is a conversation for your care team, particularly with kidney disease, heart failure, or medicines such as diuretics that affect fluid and salt balance.

Differences too small to count

Sodium figures on labels are rounded, and knowing the rule keeps you from chasing meaningless gaps. Under federal labeling regulations, sodium is declared as zero when a serving contains less than 5 mg, to the nearest 5 mg increment between 5 and 140 mg, and to the nearest 10 mg increment above 140 mg.

In practice, a label reading 850 mg could describe anything from about 845 to 854 mg. Two products listing 480 mg and 490 mg might actually be 1 mg apart. As a practical matter, treat a gap of 10 mg between similar servings as a tie and pick on price, taste, or texture. Gaps of 50 mg or more are real, and gaps of 100 mg or more on a food you eat several times a week add up quickly.

That last point deserves a moment. The FDA notes that foods eaten several times a day, such as breads, can contribute a lot of sodium over a day even when a single serving is not high. Frequency multiplies small differences. A 120 mg gap in a sandwich bread eaten twice a day, five days a week, comes to about 1,200 mg across the week.

Compare the container, not just the serving

The most common reversal in label comparison happens when the packages hold different numbers of servings. Picture two cans of soup. Brand A lists 480 mg of sodium per 1 cup serving and says 2 servings per container. Brand B lists 690 mg and says 1 serving per container. Brand A's number is lower, but the whole can of Brand A supplies 960 mg while the whole can of Brand B supplies 690 mg. If you eat a can of soup for lunch, Brand B is the lower sodium lunch.

Single serving labeling is not a trick. Federal rules say that a product packaged and sold individually containing less than 200 percent of the applicable reference amount must be labeled as one serving, with the entire contents shown as that serving. That is why a 15 ounce can of soup or a 20 ounce bottle of a drink can be a single serving on the label.

Some packages hold between one and roughly three servings and carry dual column labels, with one column for a serving and another for the whole package or unit. When that second column exists, use it. It removes the multiplication and shows what the package delivers if you finish it. A separate article covers how to work out sodium for the portion you actually eat, including partial servings.

What the front of the package can and cannot settle

Words on the front are regulated, so they carry real information, but they answer a different question than the one you are asking. Low sodium means 140 mg or less per reference amount. Reduced sodium or less sodium means at least 25 percent less sodium than an appropriate reference food, and the label must identify that reference food and show the comparison. No salt added and unsalted describe how the food was processed, not how much sodium it contains.

The gap between a claim and a number shows up most with relative claims. A reduced sodium version of a very salty food is still measured against that salty original, so it can qualify for the claim and remain a high sodium food. The claim tells you a product changed. The milligram figure tells you where it landed. A separate article in this series works through each claim in detail.

The FDA has proposed adding a front of package Nutrition Info box that would rate saturated fat, sodium, and added sugars as Low, Med, or High alongside percent Daily Value. The comment period on that proposal closed in July 2025 and no final rule has been issued, so it is a proposal rather than something you will find on shelves. Until then, the Nutrition Facts panel on the back or side remains the place where the comparison gets settled.

Keep your comparisons current

Sodium amounts in packaged food are a moving target, and that is mostly good news for shoppers. The FDA issued voluntary short term sodium reduction targets for 163 categories of packaged and restaurant food in October 2021, and reported that by 2022 about 40 percent of those targets had already been reached or were within 10 percent. A second set of draft targets issued in August 2024 aims to bring average intake to roughly 2,750 milligrams a day; that guidance was still in draft form as of the FDA page's most recent update.

Reformulation means the product you rejected two years ago may have changed, and the one you settled on may have changed too. Rechecking a few labels once a year in the categories you buy most is enough to stay current.

A habit that makes this stick: compare two products at a time, in one category per shopping trip, and photograph the label of the one you choose. The photo captures the gram serving size and the milligram figure, which is everything you need to compare against something new later, and it travels easily to anyone else who shops for your household. A separate article offers a worksheet for recording what you find.

Choosing between two labels is not a treatment, and no single swap changes much on its own. What the evidence supports is the direction. The American Heart Association says that for most people, cutting back by 1,000 mg a day can improve blood pressure, and the 2025 American Heart Association and American College of Cardiology high blood pressure guideline estimates that sodium reduction is associated with a drop of roughly 6 to 8 mm Hg in systolic pressure, the top number, among adults with high blood pressure. Those estimates come from sustained change across many foods, which is exactly what a repeatable comparison habit builds. Start with the category you buy most often, because that is where an equal serving comparison pays you back every week.