How this instrument works
Table salt is sodium chloride, a compound built from one sodium atom bonded to one chlorine atom. Sodium's atomic mass is about 23; the compound as a whole, sodium plus chlorine, comes to about 58.44. Divide 23 by 58.44 and the answer is almost exactly 39.3 percent — the share of salt's total mass that's actually sodium, and the exact multiplier this calculator applies to whatever weight you enter.
Public-health messaging from agencies like the CDC and American Heart Association often rounds that figure to a simpler 40 percent, or 'multiply by two and a half,' for everyday communication where a cleaner number matters more than the third decimal place. This calculator instead uses the precise 39.3 percent chemistry value, so its output sits a touch lower than a quick mental estimate built on the rounded rule.
A commonly cited reference point ties the two together: about 6 grams of salt, roughly a level teaspoon, works out to close to 2,300 milligrams of sodium — near the upper daily sodium limit that several major dietary guidelines recommend for most adults. That single teaspoon comparison is a useful mental anchor for reading any output this tool gives back.
- Enter Salt / sodium chloride (grams) — the weight of table salt you're converting.
- Read Sodium content (mg), the precise 39.3 percent share of that weight.
- Compare the result against a daily sodium guideline, commonly 2,300 milligrams for most healthy adults, to see how a given amount of salt fits into a day.
Worked example — 5 grams of salt
5 grams of salt: 5 × 393 = 1,965 milligrams of sodium — noticeably below the 2,000 milligrams a rougher 'times 400' estimate would have suggested for the same amount.
6 grams, close to a level teaspoon, comes to 2,358 milligrams of sodium — right around the roughly 2,300-milligram figure often cited as a full day's recommended sodium limit. Half that amount, 2.5 grams, converts to 982.5 milligrams.
Questions
Why 39.3 percent and not 40?
Because that's what the actual chemistry gives you: sodium's atomic mass, about 23, divided by sodium chloride's molecular mass, about 58.44, comes out to 39.3 percent almost exactly. Public-health communication frequently rounds that to a cleaner 40 percent for easier mental math, but this calculator keeps the more precise figure, so its numbers run very slightly below a quick times-0.4 estimate.
Is salt the same thing as sodium?
No, and mixing them up is one of the most common sources of confusion in nutrition labeling. Salt, or sodium chloride, is a compound of which sodium is only part — a bit over a third by weight, chlorine making up the rest. A gram of salt is not a gram of sodium; this calculator exists specifically to convert between the two.
How much sodium should I actually be aiming for in a day?
Major dietary guidelines commonly cite a limit around 2,300 milligrams a day for most healthy adults, with some organizations suggesting an even lower target of about 1,500 milligrams for people with elevated blood pressure risk. This calculator converts a salt amount into a sodium figure so you can compare it against whichever guideline applies to you; it doesn't set that target itself.
Does this account for salt substitutes or seasoned salts?
No — the 39.3 percent figure applies specifically to plain sodium chloride, ordinary table or cooking salt. Potassium-based salt substitutes, seasoned salt blends, and specialty finishing salts can have meaningfully different sodium content per gram, so run this conversion only on amounts of genuine, unmixed sodium chloride.
Why does sodium intake matter for health?
Consistently high sodium intake is linked in the research literature to elevated blood pressure, which in turn raises long-term risk for heart disease and stroke — the core reason agencies like the CDC and American Heart Association publish daily sodium limits in the first place. This tool only handles the conversion arithmetic; it isn't a substitute for guidance tailored to your own blood pressure or medical history.
References
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.