Created By : Rina Nayak

Reviewed By : Phani Ponnapalli

Last Updated : May 02, 2023


The molecular weight of a chemical compound can be calculated using the Molecular Weight Calculator, which is a useful online tool. Enter the chemical compound as input and examine the molecular weight as output in a matter of seconds by clicking the blue colour calculate button.

Number of elements

Element 1
Number of atoms of element 1

Element 2
Number of atoms of element 2

Steps to Calculate the Molecular Weight

Have a look at the step by step procedure on how to find any chemical compound molecular weight easily.

  • Let us take any chemical compound.
  • Get the atomic weight of the each of the element included in the compound.
  • Also, make a note of the number of atoms of each type.
  • Multiply the number of atoms by the atomic weight of each element
  • Add the products to get the final molecular weight.

Molar Mass Versus Molecular Weight

Molar mass and molecular weight are identical values, but they are not exactly the same

Molar Mass Molecular Weight
It is the mass of a mole of a substance It is the mass of the single molecule of the substance
The SI unit is g/mol Measured in amu or u
Defined as the mass of Avogadro number of atoms Defined as the sum of the atomic masses of all atoms in a molecule of the substance
Molar mass of HCl is 17g/mol Molecular weight of HCl is 36.5 u.

Table of Atomic Weights and Elements

Atomic Number Element Name Atomic Symbol Atomic Weight (g/mol)
1 Hydrogen H 1.00794
2 Helium He 4.002602
3 Lithium Li 6.941
4 Beryllium Be 9.012182
5 Boron B 10.811
6 Carbon C 12.0107
7 Nitrogen N 14.0067
8 Oxygen O 15.9994
9 Fluorine F 18.9984032
10 Neon Ne 20.1797
11 Sodium Na 22.98976928
12 Magnesium Mg 24.3050
13 Aluminum Al 26.9815386
14 Silicon Si 28.0855
15 Phosphorus P 30.973762
16 Sulfur S 32.065
17 Chlorine Cl 35.453
18 Argon Ar 39.948
19 Potassium K 39.0983
20 Calcium Ca 40.078
21 Scandium Sc 44.955912
22 Titanium Ti 47.867
23 Vanadium V 50.9415
24 Chromium Cr 51.9961
25 Manganese Mn 54.938045
26 Iron Fe 55.845
27 Cobalt Co 58.933195
28 Nickel Ni 58.6934
29 Copper Cu 63.546
30 Zinc Zn 65.409
31 Gallium Ga 69.723
32 Germanium Ge 72.64
33 Arsenic As 74.92160
34 Selenium Se 78.96
35 Bromine Br 79.904
36 Krypton Kr 83.798
37 Rubidium Rb 85.4678
38 Strontium Sr 87.62
39 Yttrium Y 88.90585
40 Zirconium Zr 91.224
41 Niobium Nb 92.906 38
42 Molybdenum Mo 95.94
43 Technetium Tc 98.9063
44 Ruthenium Ru 101.07
45 Rhodium Rh 102.90550
46 Palladium Pd 106.42
47 Silver Ag 107.8682
48 Cadmium Cd 112.411
49 Indium In 114.818
50 Tin Sn 118.710
51 Antimony Sb 121.760
52 Tellurium Te 127.60
53 Iodine I 126.90447
54 Xenon Xe 131.293
55 Caesium Cs 132.9054519
56 Barium Ba 137.327
57 Lanthanum La 138.90547
58 Cerium Ce 140.116
59 Praseodymium Pr 140.90765
60 Neodymium Nd 144.242
61 Promethium Pm 146.9151
62 Samarium Sm 150.36
63 Europium Eu 151.964
64 Gadolinium Gd 157.25
65 Terbium Tb 158.92535
66 Dysprosium Dy 162.500
67 Holmium Ho 164.93032
68 Erbium Er 167.259
69 Thulium Tm 168.93421
70 Ytterbium Yb 173.04
71 Lutetium Lu 174.967
72 Hafnium Hf 178.49
73 Tantalum Ta 180.9479
74 Tungsten W 183.84
75 Rhenium Re 186.207
76 Osmium Os 190.23
77 Iridium Ir 192.217
78 Platinum Pt 195.084
79 Gold Au 196.966569
80 Mercury Hg 200.59
81 Thallium Tl 204.3833
82 Lead Pb 207.2
83 Bismuth Bi 208.98040
84 Polonium Po 208.9824
85 Astatine At 209.9871
86 Radon Rn 222.0176
87 Francium Fr 223.0197
88 Radium Ra 226.0254
89 Actinium Ac 227.0278
90 Thorium Th 232.03806
91 Protactinium Pa 231.03588
92 Uranium U 238.02891
93 Neptunium Np 237.0482
94 Plutonium Pu 244.0642
95 Americium Am 243.0614
96 Curium Cm 247.0703
97 Berkelium Bk 247.0703
98 Californium Cf 251.0796
99 Einsteinium Es 252.0829
100 Fermium Fm 257.0951
101 Mendelevium Md 258.0986
102 Nobelium No 259.1009
103 Lawrencium Lr 260.1053
104 Rutherfordium Rf 261.1087
105 Dubnium Db 262.1138
106 Seaborgium Sg 263.1182
107 Bohrium Bh 262.1229
108 Hassium Hs 265
109 Meitnerium Mt 266
110 Darmstadtium Ds 269
111 Roentgenium Rg 272
112 Ununbium Uub 285
113 Ununtrium Uut 284
114 Ununquadium Uuq 289
115 Ununpentium Uup 288
116 Ununhexium Uuh 292
118 Ununoctium Uuo 294

Example:

Question: Find the molecular weight of H2SO4?

Answer:

Given chemical compound is H2SO4

The number hydrogen atoms = 2

The number of Sulphur atoms = 1

The number of oxygen atoms = 4

Mass of hydrogen = 1 u

Mass of sulphur = 32.06 u

Mass of oxygen = 15.99 u

Molecular weight of H2SO4 = (2 x 1) + 32.06 + (4 x 15.99)

= 2 + 32.06 + 63.96 = 98.02

Therefore, H2SO4 MW is 98.02 u

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FAQ’s on Molecular Weight Calculator

1. How to use Molecular Weight Calculator?

You have to enter the chemical compound in the input field and press the calculate button to check the molecular weight of that compound easily.


2. What are the differences between molar mass and molecular weight?

The molar mass is defined as the mass of the mole of a substance and its unit is gram per mol. The molecular weight is the mass of a molecule and its unit is an atomic unit. Molar mass is calculated by dividing the mass of the substance by the amount of the substance. Molecular weight is 1/12th of the mass of the carbon-12 atom.


3. Find the molecular weight of NaCl?

Given chemical compound is NaCl

The atomic weight of Na = 22.98

The atomic weight of Cl = 35.45

The molecular weight of NaCl = 1 x 22.98 + 1 x 35.45 = 58.43 u.


4. What is the molecular weight definition?

The molecular weight is defined as the mass of a molecule of a substance. Its unit is an atomic unit and it is also called the relative molecular weight.