What this calculator does
Converting grams to millilitres is not a fixed conversion the way converting kilometres to miles is, because grams measure mass and millilitres measure volume, and the link between the two depends on how dense the substance is. Water happens to sit almost exactly at 1 gram per millilitre, which is why the two get treated as interchangeable so often, but flour, honey, oil and most other ingredients do not.
This calculator asks for the density of whatever you are converting, in grams per millilitre, and defaults to 1.00 for water so it behaves the way people expect for the common case. Change that figure for anything else: honey sits around 1.42 g/mL, vegetable oil around 0.92 g/mL, and flour is lighter still and varies with how it is packed.
The formula
Grams to millilitres divides the mass by the density; millilitres to grams multiplies the volume by the density. Both directions use the same density figure, entered as grams per millilitre, so getting that number right for the actual substance is what makes the conversion accurate rather than just a guess based on water.
| Term | Meaning |
|---|---|
| Density | Mass per unit volume of the substance being converted, in grams per millilitre. |
| Grams | A measure of mass, unaffected by what the substance is or how it is packed. |
| Millilitres | A measure of volume; one millilitre of water weighs almost exactly one gram, but that is a coincidence of water's density, not a general rule. |
The inputs explained
| Field | What to enter |
|---|---|
| Convert | Choose whether you are converting a weight in grams to a volume in millilitres, or the other way round. |
| Amount | The quantity to convert, in grams or millilitres depending on the direction chosen. |
| Density of the substance (g/mL) | The density of the substance in grams per millilitre. Leave at 1.00 for water; look up or measure the figure for anything else. |
When to use it
Following a recipe given in the wrong unit
A recipe written in millilitres and a kitchen scale that only reads grams (or vice versa) need a real conversion, and for anything other than water or a water-like liquid, the ingredient's density matters to get the amount right.
Converting a liquid ingredient by density
Oils, syrups and alcohol all have densities noticeably different from water, so scaling a recipe between weight and volume for these needs the correct density figure rather than a straight 1:1 substitution.
Checking a packaging or dosage conversion
Some labels state a fill by weight and others by volume; converting between them correctly requires knowing the product's density rather than assuming it behaves like water.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Converting 100 g to millilitres at different densities
The same 100 g of substance, converted to millilitres as density varies from water up to a much heavier liquid.
| Density | 100.00 g converts to |
|---|---|
| 0.50 g/mL | 200.000 mL |
| 0.70 g/mL | 142.857 mL |
| 0.92 g/mL | 108.696 mL |
| 1.00 g/mL | 100.000 mL |
| 1.42 g/mL | 70.423 mL |
| 2.00 g/mL | 50.000 mL |
Converting 100 mL to grams at different densities
The same 100 mL of substance, converted to grams as density varies.
| Density | 100.00 mL converts to |
|---|---|
| 0.50 g/mL | 50.000 g |
| 0.70 g/mL | 70.000 g |
| 0.92 g/mL | 92.000 g |
| 1.00 g/mL | 100.000 g |
| 1.42 g/mL | 142.000 g |
| 2.00 g/mL | 200.000 g |
Questions
Is 1 gram always equal to 1 millilitre?
Only for a substance with a density of exactly 1.00 g/mL, which water is close enough to for most everyday purposes. For anything else, such as oil, honey or flour, 1 gram and 1 millilitre are different amounts, and the gap depends on how dense that substance is.
Where do I find the density of an ingredient?
Density figures for common cooking ingredients are widely published and vary a little by source and by how tightly a dry ingredient like flour is packed. When precision matters, weighing a known volume of the actual substance you have on hand gives the most accurate figure.
Why does this calculator ask for density instead of just converting directly?
A direct grams-to-millilitres conversion with no density input would silently assume the substance behaves exactly like water, which is wrong for most ingredients and could throw off a recipe or a dosage. Making density an explicit, editable input keeps the conversion honest.
Does temperature affect the conversion?
Density does shift slightly with temperature, since most substances expand a little when warmed, which very marginally changes how much volume a given mass takes up. For typical kitchen and household use this effect is small enough to ignore against the density differences between substances themselves.
For a specific baking ingredient rather than a general density figure, the grams in a tablespoon calculator and the grams to cups calculator use typical densities already built in.