Molecular Weight Calculator (Molar Mass)

Please enter or select the molecular formula of a molecule to calculate its molecular weight/molar mass. Note that the formula is case-sensitive. This calculator utilizes the abridged standard atomic weights published by IUPAC with uncertainty ignored.

Molecular Formula Common Chemicals -- Select -- H2O (Water) CO2 (Carbon Dioxide) NH3 (Ammonia) NaCl (Table Salt (Sodium Chloride)) H2SO4 (Sulfuric Acid) HCl (Hydrochloric Acid) HNO3 (Nitric Acid) NaHCO3 (Sodium Bicarbonate (Baking Soda)) CaCO3 (Calcium Carbonate) KCl (Potassium Chloride) [Co(NH3)6]Cl3 (Hexaamminecobalt(III) chloride) KMnO4 (Potassium permanganate) CuSO4.5H2O (Copper(II) sulfate pentahydrate) CH4 (Methane) C2H5OH (Ethanol) C2H4O2 (Acetic Acid) C6H12O6 (Glucose) C6H6 (Benzene) C8H18 (Octane) C12H22O11 (Sucrose) C9H8O4 (Aspirin) C6H8O7 (Citric Acid) CH4N2O (Urea)

Atomic weight, molecular weight, and molar mass are fundamental concepts in chemistry. These measurements are essential for calculating the quantities of substances involved in chemical reactions, determining concentrations, analyzing molecular properties, and many other situations.

Atomic Weight

Atomic weight is the average mass of the atoms of a chemical element, expressed in atomic mass units (amu). It represents the weighted average of the masses of an element's naturally occurring isotopes based on their abundance. Atomic weight is a dimensionless quantity because it is the ratio of the average mass of atoms to one unified atomic mass unit (u) or Dalton (Da), which is defined as one-twelfth the mass of a carbon-12 atom.

Below is a table of the abridged standard atomic weights of the elements. The abridged version is commonly used in practical scenarios, as it simplifies calculations by providing values rounded to a fixed number of decimal places, ignoring the typically small natural variations in isotope ratios from different sources or samples. These values are published by the International Union of Pure and Applied Chemistry (IUPAC). The calculations of this calculator are based on this data.

Atomic Number	Symbol	Name	Atomic Weight (g/mol)	Density (g/cm3)	Phase at Room Temp.
1	H	Hydrogen	1.008	0.00008988	gas
2	He	Helium	4.0026	0.0001785	gas
3	Li	Lithium	6.94	0.534	solid
4	Be	Beryllium	9.0122	1.85	solid
5	B	Boron	10.81	2.34	solid
6	C	Carbon	12.011	2.267	solid
7	N	Nitrogen	14.007	0.0012506	gas
8	O	Oxygen	15.999	0.001429	gas
9	F	Fluorine	18.998	0.001696	gas
10	Ne	Neon	20.18	0.0009002	gas
11	Na	Sodium	22.99	0.968	solid
12	Mg	Magnesium	24.305	1.738	solid
13	Al	Aluminium	26.982	2.7	solid
14	Si	Silicon	28.085	2.329	solid
15	P	Phosphorus	30.974	1.823	solid
16	S	Sulfur	32.06	2.07	solid
17	Cl	Chlorine	35.45	0.0032	gas
18	Ar	Argon	39.95	0.001784	gas
19	K	Potassium	39.098	0.89	solid
20	Ca	Calcium	40.078	1.55	solid
21	Sc	Scandium	44.956	2.985	solid
22	Ti	Titanium	47.867	4.506	solid
23	V	Vanadium	50.942	6.11	solid
24	Cr	Chromium	51.996	7.15	solid
25	Mn	Manganese	54.938	7.21	solid
26	Fe	Iron	55.845	7.874	solid
27	Co	Cobalt	58.933	8.9	solid
28	Ni	Nickel	58.693	8.908	solid
29	Cu	Copper	63.546	8.96	solid
30	Zn	Zinc	65.38	7.14	solid
31	Ga	Gallium	69.723	5.91	solid
32	Ge	Germanium	72.63	5.323	solid
33	As	Arsenic	74.922	5.727	solid
34	Se	Selenium	78.971	4.81	solid
35	Br	Bromine	79.904	3.1028	liquid
36	Kr	Krypton	83.798	0.003749	gas
37	Rb	Rubidium	85.468	1.532	solid
38	Sr	Strontium	87.62	2.64	solid
39	Y	Yttrium	88.906	4.472	solid
40	Zr	Zirconium	91.224	6.52	solid
41	Nb	Niobium	92.906	8.57	solid
42	Mo	Molybdenum	95.95	10.28	solid
43	Tc	Technetium	97	11	solid
44	Ru	Ruthenium	101.07	12.45	solid
45	Rh	Rhodium	102.91	12.41	solid
46	Pd	Palladium	106.42	12.023	solid
47	Ag	Silver	107.87	10.49	solid
48	Cd	Cadmium	112.41	8.65	solid
49	In	Indium	114.82	7.31	solid
50	Sn	Tin	118.71	7.265	solid
51	Sb	Antimony	121.76	6.697	solid
52	Te	Tellurium	127.6	6.24	solid
53	I	Iodine	126.9	4.933	solid
54	Xe	Xenon	131.29	0.005894	gas
55	Cs	Caesium	132.91	1.93	solid
56	Ba	Barium	137.33	3.51	solid
57	La	Lanthanum	138.91	6.162	solid
58	Ce	Cerium	140.12	6.77	solid
59	Pr	Praseodymium	140.91	6.77	solid
60	Nd	Neodymium	144.24	7.01	solid
61	Pm	Promethium	145	7.26	solid
62	Sm	Samarium	150.36	7.52	solid
63	Eu	Europium	151.96	5.244	solid
64	Gd	Gadolinium	157.25	7.9	solid
65	Tb	Terbium	158.93	8.23	solid
66	Dy	Dysprosium	162.5	8.54	solid
67	Ho	Holmium	164.93	8.79	solid
68	Er	Erbium	167.26	9.066	solid
69	Tm	Thulium	168.93	9.32	solid
70	Yb	Ytterbium	173.05	6.9	solid
71	Lu	Lutetium	174.97	9.841	solid
72	Hf	Hafnium	178.49	13.31	solid
73	Ta	Tantalum	180.95	16.69	solid
74	W	Tungsten	183.84	19.25	solid
75	Re	Rhenium	186.21	21.02	solid
76	Os	Osmium	190.23	22.59	solid
77	Ir	Iridium	192.22	22.56	solid
78	Pt	Platinum	195.08	21.45	solid
79	Au	Gold	196.97	19.3	solid
80	Hg	Mercury	200.59	13.534	liquid
81	Tl	Thallium	204.38	11.85	solid
82	Pb	Lead	207.2	11.34	solid
83	Bi	Bismuth	208.98	9.78	solid
84	Po	Polonium	209	9.196	solid
85	At	Astatine	210		NA
86	Rn	Radon	222	0.00973	gas
87	Fr	Francium	223		NA
88	Ra	Radium	226	5.5	solid
89	Ac	Actinium	227	10	solid
90	Th	Thorium	232.04	11.7	solid
91	Pa	Protactinium	231.04	15.37	solid
92	U	Uranium	238.03	19.1	solid
93	Np	Neptunium	237	20.45	solid
94	Pu	Plutonium	244	19.85	solid
95	Am	Americium	243	12	solid
96	Cm	Curium	247	13.51	solid
97	Bk	Berkelium	247	14.78	solid
98	Cf	Californium	251	15.1	solid
99	Es	Einsteinium	252	8.84	solid
100	Fm	Fermium	257		NA
101	Md	Mendelevium	258		NA
102	No	Nobelium	259		NA
103	Lr	Lawrencium	266		NA
104	Rf	Rutherfordium	267		NA
105	Db	Dubnium	268		NA
106	Sg	Seaborgium	267		NA
107	Bh	Bohrium	270		NA
108	Hs	Hassium	271		NA
109	Mt	Meitnerium	278		NA
110	Ds	Darmstadtium	281		NA
111	Rg	Roentgenium	282		NA
112	Cn	Copernicium	285		NA
113	Nh	Nihonium	286		NA
114	Fl	Flerovium	289		NA
115	Mc	Moscovium	290		NA
116	Lv	Livermorium	293		NA
117	Ts	Tennessine	294		NA
118	Og	Oganesson	294		NA

Molecular Weight

Molecular weight is the sum of the atomic weights of all atoms in a molecule's chemical formula. Like atomic weight, it represents the mass of a single molecule and is expressed in atomic mass units (amu) or Daltons (Da).

Molar Mass

Molar mass is the mass of one mole of a substance (6.022 × 10²³ particles, Avogadro's number) and is expressed in grams per mole (g/mol). It connects the microscopic world of atoms and molecules with the macroscopic quantities measured in the laboratory.

While molecular weight is the mass of a single molecule in atomic mass units, molar mass is the mass of Avogadro's number of molecules in grams. Numerically, they have the same value, but the units are different. Therefore, they are often used interchangeably. Similarly, atomic weight can also be expressed in grams per mole (g/mol).

Calculate Molecular Weight and Molar Mass

Atomic weight serves as the foundation for calculating molecular weight and molar mass. It provides the mass of individual atoms, which, when combined according to a molecule's chemical formula, yields the mass of the entire molecule. Therefore, molecular weight or molar mass can be calculated by:

• Identify and count the number of atoms of each element in the molecule.
• Obtain the atomic weights of each element using the standard atomic weights from the periodic table or the table provided above.
• Multiply the atomic weight of each element by the number of atoms of that element, then sum the results.

The following are some examples:

Some molecules have more complex formulas, including those with parentheses or hydrates.

	Search