Weight to Volume, and Back, for a Substance You Choose
Nine tenths of the mass-to-volume pairs anyone searches for are the same arithmetic with different unit labels. Quarts to pounds, cc to ounces, millilitres to kilograms, decilitres to ounces — each is one division by a density, and none of them has anything to say that the others do not. So they share a page. Pick the pair from the presets or set the two units yourself, choose a substance, and the answer comes with the density it used and where that density came from.
Adjust the inputs and select Calculate for a full breakdown.
Solution method, checks and interpretation
Weight to Volume, and Back, for a Substance You Choose is worked through as a complete solution: scenario, method, formula, substitution and interpretation.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Converted amount | Density used (g/mL) | Same amount in grams | Same amount in millilitres |
|---|---|---|---|---|
| 16 qt of water in pounds | 33.3217 | 0.998204 | 15,114.5 | 15,141.6 |
| 1 qt of water in pounds | 2.08261 | 0.998204 | 944.654 | 946.353 |
| 1 US gallon of water in grams | 3,778.62 | 0.998204 | 3,778.62 | 3,785.41 |
| 500 mg of water in cc | 0.500899 | 0.998204 | 0.5 | 0.500899 |
| 200 mL of milk in kg | 0.206266 | 1.03133 | 206.266 | 200 |
| 30 cc of olive oil in ounces | 0.966132 | 0.912979 | 27.3894 | 30 |
| 100 cc of water in pounds | 0.220066 | 0.998204 | 99.8204 | 100 |
| 1 dL of water in ounces | 3.52106 | 0.998204 | 99.8204 | 100 |
| 250 cc of honey in kg | 0.3575 | 1.43 | 357.5 | 250 |
| 1 L of water in mg | 998,204 | 0.998204 | 998.204 | 1,000 |
How This Calculator Works
Every conversion here is m = ρV rearranged. Going from a weight to a volume divides by the density; going the other way multiplies. The unit factors on both sides are exact by definition — a pound is 0.45359237 kg, a US gallon is 231 cubic inches, a cubic centimetre is a millilitre — so they contribute no error, and the density is the only measured number in the calculation. That is why the page shows it rather than hiding it in a footnote.
The Formula
Mass and volume through density
ρ is the density of the substance you choose, in grams per millilitre. It is a measured property, not a constant: water is 0.998 g/mL at 20 °C, olive oil 0.913, honey 1.43. Unit definitions on both sides are exact (1 lb = 0.45359237 kg, 1 US gallon = 231 in³), so every uncertainty in the answer comes from the density and none from the units.
Worked Example
A 16-quart stockpot of water holds 33.4 lb. The same pot of honey would hold 47.8 lb, which is more than most people expect and more than some pot handles are rated for. Two hundred millilitres of milk is 0.206 kg. Thirty cc of olive oil is 0.966 oz. One gallon of water is 3,779 grams.
Key Insight
A converter that handles every pair has one disadvantage over a page built for a single pair: it cannot tell you what people usually get wrong about YOUR conversion. That is a real cost, and it is why pounds to gallons, grams to litres, millilitres to milligrams and five others have their own pages here — each had a specific confusion worth a page. The pairs on this page did not. A page about decilitres to ounces would repeat what a page about cubic centimetres to pounds already said, and a site full of those is how a useful tool turns into doorway pages. The honest version is one good tool with the presets in it.
Frequently Asked Questions
Which unit pairs can this convert?
Any of six weight units against any of nine volume units, in either direction — ninety directed pairs. The presets cover the ones people search for most, and the two dropdowns cover the rest.
How many pounds is 16 quarts?
Of water, 33.4 lb. Of honey, 47.8. A quart is a volume and a pound is a weight, so the substance is what decides.
How many ounces is 30 cc?
Of water, 1.056 oz by weight. A cc is exactly a millilitre, so 30 cc is 30 mL, and the weight follows from the density.
Why is there a separate page for pounds to gallons?
Because that pair has a specific thing worth saying — a gallon of water is 8.33 lb and people remember 8.34, which is a rounding of two different temperatures. Pairs without their own story share this page instead.
Does it convert between two weights, or two volumes?
Yes, and it will tell you that no density was used, because for a same-quantity conversion the substance cancels out and does not matter.
What if my substance is not listed?
The page says so. It does not interpolate, does not borrow the density of something with a similar name, and does not quietly fall back to water — which is what most converters do when they do not ask.
Is a cc the same as a mL?
Yes, exactly, by definition. Both appear in the list because people search for both.
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Assumptions
- The substance is the one you choose. There is no default and no fallback: a weight becomes a volume only through a density, and a density belongs to a particular substance.
- Water is offered at two temperatures because the difference is the reason '1 g/mL' and '998 g/L' are both correct. At 20 °C a US gallon of water is 8.33 lb; at 4 °C, its densest, it is 8.35.
Limitations & Disclaimer
This is an educational tool, not financial advice. It does not account for your personal circumstances, and no result is a guarantee.
- It converts for five substances and refuses six more in writing. A substance that is not in the table is said out loud; the page never interpolates, never guesses from a similar name and never quietly falls back to water.
- Flour, granulated sugar, potting soil and creatine are bulk solids whose density depends on packing. Packed and sifted flour differ by more than 40 percent, which is larger than the conversion itself, so no single number is offered.
- Jet fuel is defined by ASTM D1655 and DEF STAN 91-091 as a spec band rather than a value, and neither standard is readable without paying for it. An aviation figure taken from a converter site would not be a source.
- USDA states no temperature for the food densities. That is shown on the page rather than replaced with a plausible 20 °C.
Methodology & Review
One engine, fifteen units and five sourced densities. Six mass units (g, kg, mg, µg, lb, oz) and nine volume units (L, mL, dL, µL, cc, US gal, US fl oz, US qt, US pt) give ninety directed mass-volume pairs, every one of which is m = ρV with the same exactly-defined unit factors on both sides. The pairs below are the ones people actually searched for and that do not have enough of their own to say to earn a page each.
External financial review: No independent third-party review. Every density is derived at build time from a named primary source — NIST Chemistry WebBook for water, USDA FoodData Central SR Legacy for the foods — and a drift check re-derives them and fails if a source moves..
Reviewed according to the CalcDomain Editorial Policy & Calculator Methodology. We document formulas, edge cases, sources, update dates, and correction paths for calculator pages.
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