Milligrams to Grams

Putting a Milligram Label Figure Next to a Gram Total

Labels rarely stay in one unit. A tablet is stamped 500 mg, the caffeine line on a drink can says 80 mg, a supplement panel mixes milligrams with micrograms, and the nutrition table you want to compare all of it against is printed in grams per 100 g. Getting them onto the same scale is the whole job, and it is one step of arithmetic.

Conversion factor: 1 mg = 0.001 g, so divide milligrams by 1,000 — three decimal places to the left. A serving listing 430 mg of sodium contains 0.43 g, and a 500 mg tablet is half a gram of active ingredient.

Why Labels Keep Switching Units

Tablet strengths are milligram figures

Almost every oral strength is printed in mg, from 5 mg up to 1000 mg, because that range keeps the number a whole one or two digits instead of a string of decimals.

Caffeine is always stated in mg

Coffee, tea, energy drinks and caffeine tablets all declare milligrams per serving, which makes them directly comparable — provided you check what the serving actually is.

Panels change unit mid-column

Fat, carbohydrate and protein appear in grams; sodium, potassium and cholesterol in milligrams; most vitamins in micrograms. Each is chosen so the printed figure stays readable.

The serving size sets the number

Every figure on the panel is per serving, not per pack. A 400 mg line means little until you know whether the serving is one capsule, two scoops or half a tin.

Reading One Panel Against Another

The usual task is comparison: one product prints milligrams, the other prints grams, and you want to know which is the bigger number.

Type the figure exactly as the label prints it

Enter 200, 430 or 1 000 in the left field and the gram value appears immediately. A comma is accepted as the decimal separator and spaces used as thousands grouping are ignored.

Drop to micrograms when the panel does

Search either dropdown for microgram and a 400 µg folate line becomes 0.4 mg, sitting on the same scale as the milligram entries beside it.

Copy the value into whatever is keeping the tally

The copy button hands over the number alone, with no unit and no spacing, which is what a spreadsheet cell or a tracking app field will accept. Ctrl + C in a field does the same.

Go the other way for a gram-based panel

European labels often print salt as 1.2 g. Press the swap button (↔) to run g → mg and that becomes 1 200 mg, ready to compare with a milligram sodium line.

The compound and the element are two different weights: a 325 mg ferrous sulfate tablet supplies roughly 65 mg of elemental iron, and the panel usually names which one it is quoting. Converting mg to g never changes that distinction — read the wording, not just the number. This page is about reading labels, not about how much of anything to take; follow the product's own instructions.

Label Strengths You Meet Most, in mg and g

Recognisable milligram figures and what they come to once the decimal point moves three places.

Label figure	Where it typically appears	Grams
5 mg	A melatonin tablet	0.005 g
50 mg	A zinc supplement capsule	0.05 g
95 mg	Caffeine in a 240 ml cup of brewed coffee	0.095 g
200 mg	A caffeine tablet	0.2 g
400 mg	Sodium in one serving of canned soup	0.4 g
500 mg	A paracetamol (acetaminophen) tablet	0.5 g
1000 mg	A vitamin C tablet	1 g

Laid out together the scale becomes obvious: the entire column, from a 5 mg tablet to a full gram of vitamin C, fits inside the first gram. That is precisely why labels use milligrams — nobody wants to read "0.005 g" on a blister pack, and a sodium line printed as 0.43 g would look trivially small next to a 25 g carbohydrate figure on the same panel.

What Makes Label Comparison Easier Here

Thousandths stay visible

Output runs to eight decimals, so a 5 mg strength shows as 0.005 g and a 2.4 µg entry does not quietly round itself away to zero.

Micrograms one search away

Both sides carry a searchable list of every weight unit, so a panel that jumps between mg, µg and g can be lined up without leaving the page.

Reverse for gram-first labels

One press of the swap button turns a salt or sugar figure printed in grams back into the milligrams the comparison table wants.

Clean numbers for a tally

Copy delivers just the digits, which is what a spreadsheet or a daily-intake tracker expects when you are adding several servings together.

Questions About Units on Labels

What is the difference between mg and mcg on a supplement panel?

A factor of a thousand. One milligram is 1 000 micrograms, written mcg on packaging and µg in scientific text — the same unit, two spellings, because the Greek letter µ does not survive every printing and labelling system. So a 400 mcg folate line is 0.4 mg and 0.0004 g, while a 2.4 mcg vitamin B12 line is 0.0024 mg. The two abbreviations look alike at a glance on a crowded panel, which is exactly why it is worth reading the unit column deliberately rather than scanning the numbers.

Why do some vitamins appear in IU instead of a weight?

Because an International Unit measures biological activity, not mass, so it cannot be converted with a single factor — each substance has its own equivalence. For vitamin D, 1 IU corresponds to 0.025 µg, which makes a 1 000 IU capsule 25 µg or 0.025 mg. For vitamin E, 1 IU is about 0.67 mg of the natural form (d-alpha-tocopherol) but roughly 0.45 mg of the synthetic form. US Supplement Facts panels moved to micrograms and milligrams around 2019–2020, so IU figures now mostly appear on older stock and on packaging from other markets.

Why does one nutrition panel use grams on some lines and milligrams on others?

To keep every figure in a range a person can read. Macronutrients arrive in whole grams — 25 g of carbohydrate, 9 g of fat — while sodium, cholesterol and potassium arrive in hundreds of milligrams and vitamins in micrograms. Printing them all in grams would give a column of 0.43 and 0.0004, and printing them all in milligrams would give 25 000. The mixed panel is deliberate; the trap is only in comparing two lines without noticing that the unit changed between them.

My label is per serving but the table I am comparing is per 100 g — how do I line them up?

Scale by the serving mass, which the panel states near the top. Divide the figure by the serving weight in grams, then multiply by 100. A soup declaring 400 mg of sodium in a 245 g serving works out at 400 ÷ 245 × 100 ≈ 163 mg per 100 g, or 0.163 g per 100 g. This is the usual reason two products look wildly different: EU labels are built around per-100 g figures, US labels around a serving, and a generous serving size flatters a per-serving number.

Can I work backwards from a %DV percentage to the milligrams?

Yes, if you know the Daily Value the percentage is measured against, because %DV is simply that reference amount multiplied by the percentage. Sodium uses 2 300 mg, so a line reading 20% DV is 460 mg — 0.46 g. Vitamin C uses 90 mg, making 50% DV equal to 45 mg; calcium uses 1 300 mg, so 25% DV is 325 mg. The reference values are fixed by the labelling rules rather than by the product, and they differ between regions, so check which scheme the pack follows before comparing percentages across borders.