How this instrument works
A litre is defined as one cubic decimetre, and a decimetre is ten centimetres. Cube that ten and you get 1000, which is why exactly 1000 cubic centimetres fill one litre and why 1 cc is 0.001 l with no uncertainty attached. Nothing here was measured; it falls out of decimal prefixes. Written cc is simply cm³ typed on a keyboard without superscripts, and it names the same volume as a millilitre.
That tidy identity is younger than it looks. From 1901 until 1964 a litre was defined instead as the volume occupied by one kilogram of pure water at its density maximum, near 3.98 °C. Because the prototype kilogram was very slightly off, that litre came out to 1.000028 dm³, roughly 28 parts per million too large — so a millilitre and a cc were not quite equal. In 1964 the 12th General Conference on Weights and Measures abolished the water definition, restored one litre to one cubic decimetre, and advised chemists against quoting litres in results of high accuracy. Solubility tables printed in grams per litre before that vote still carry the old offset.
Cubic centimetres survive wherever small displacements matter: motorcycle classes and licence bands at 125, 600 and 1000, Japan's 660 cc ceiling for kei cars, chainsaw and outboard catalogues, and graduated syringes in human and veterinary medicine. Litres take over once a container is worth carrying — fuel, coolant, engine oil, beer, paint. Car makers straddle both conventions, quoting swept volume in cc on a specification sheet while stamping 1.5 or 2.0 on a tailgate.
- Enter your volume in the Cubic centimetres (cc) field; it opens at 1500 cc, a typical small-car swept volume.
- Read the Litres (l) line beneath it — six decimal places, recalculated on every keystroke.
- Have millilitres instead? Type them straight in. One ml is one cc, so no arithmetic is needed first.
- Going from litres back to cc, multiply by 1000 before you type: 2.4 l becomes 2400 cc.
Worked example — 1500 cc on paper, 1.5 on the badge
A workshop manual quotes swept volume as 1500 cc while the tailgate says 1.5. Enter 1500 into Cubic centimetres (cc) and the Litres (l) line returns 1.5 exactly: four cylinders of 375 cc apiece, carried from one notation into another with nothing rounded away.
Rounding does creep in, but earlier and elsewhere. Bore and stroke get set in tenths of a millimetre, so a nominal 1500 usually works out at 1498 or 1496 cc, which is 1.498 or 1.496 l — still badged 1.5 by a marketing department. Trust this arithmetic; check instead whichever displacement figure you fed it.
Questions
Is a cc exactly the same volume as a millilitre?
Yes, and it has been since 1964. Both equal one thousandth of a litre, which is itself one cubic decimetre, so 1 cc = 1 ml = 0.001 l with nothing rounded anywhere. Between 1901 and 1964 they differed by about 28 parts per million, because the litre was then pegged to one kilogram of water rather than to any cube of side 10 cm. Only work carried to six significant figures ever noticed.
Why is the factor exactly 0.001 and not a measured value?
Because it is pure geometry. One litre is one cubic decimetre by definition, one decimetre is ten centimetres, and cubing ten gives 1000. Dividing cubic centimetres by 1000 is therefore a shift of three decimal places, never an approximation, and it holds at any precision your glassware or gauges can reach.
Should I write cc or mL in a clinical setting?
Write mL. Volumes are identical, but handwritten cc gets misread as u (for units) or as 00 often enough that safety bodies including ISMP and the Joint Commission list it among abbreviations to avoid in medication orders. NIST likewise prefers cm³ or mL in technical writing, and recommends a capital L for the litre in the United States, since lowercase l is easily mistaken for a digit 1. Both symbols were accepted by the 16th CGPM in 1979.
How do cubic inches convert into cc and litres?
Multiply cubic inches by 16.387064 for cc, then by 0.001 for litres. That factor is exact, since an inch is exactly 2.54 cm and 2.54 cubed is 16.387064. A 350 cubic inch V8, for instance, displaces 5735.5 cc, which reaches showrooms badged as 5.7 l.
What goes wrong most often with this conversion?
Shifting two decimal places instead of three. Centi- suggests hundredths, yet the cubic centimetre is one thousandth of the litre, because prefixes get cubed along with whatever length they modify. Watch the next step up too: 1 l is 0.001 m³, which puts 1 cc at 0.000001 m³. And mass is not volume — 1 cc of water weighs about 0.998 g at room temperature, not exactly 1 g.
Is a litre an SI unit at all?
Strictly, no. The coherent SI unit of volume is the cubic metre; a litre belongs to a short list of non-SI units accepted for use alongside it, kept on because it suits everyday trade and laboratory glassware. That status explains why one volume can be written 1500 cc, 1500 cm³, 1500 ml, 1.5 dm³ or 1.5 l, and why chemists reporting to high accuracy were pointed toward cubic decimetres in 1964.