Molar mass calculator from a chemical formula

Molar mass of a compound from its element counts, with mass percent and a grams-to-moles converter.

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	A	B	C	D	E	F
1	Molar mass calculator from a chemical formula
2	Example data — replace the blue input cells with your own.
3
4	MOLAR MASS (G/MOL)		NUMBER OF ATOMS		HEAVIEST ELEMENT BY MASS
5	194.19		24		C
6
7	Compound: Caffeine (example)
8	Compound name	Caffeine (example)	Label only
9	Formula (text, for the record)	C8H10N4O2	Typed for reference; the element rows below do the arithmetic
10	Check	OK	Symbols are matched without regard to case. Enter Co and CO as elements, never as one string.
11
12	Element symbol	Count	Atomic weight (g/mol)	Mass contribution (g/mol)	Mass percent	Element name
13	C	8	12.011	96.09	49.5%	Carbon
14	H	10	1.008	10.08	5.2%	Hydrogen
15	N	4	14.007	56.03	28.9%	Nitrogen
16	O	2	15.999	32.00	16.5%	Oxygen

Showing the first 16 of 55 rows and 7 of 7 columns. Cells with formulas show the formula on hover.

	A	B	C	D	E
1	Standard atomic weights (abridged IUPAC values)
2	Atomic number, symbol, name and standard atomic weight in g/mol. Starred rows show a mass number.
3
4	Atomic number	Symbol	Element	Atomic weight (g/mol)	Note
5	1	H	Hydrogen	1.008
6	2	He	Helium	4.0026
7	3	Li	Lithium	6.94
8	4	Be	Beryllium	9.0122
9	5	B	Boron	10.81
10	6	C	Carbon	12.011
11	7	N	Nitrogen	14.007
12	8	O	Oxygen	15.999
13	9	F	Fluorine	18.998
14	10	Ne	Neon	20.18
15	11	Na	Sodium	22.99
16	12	Mg	Magnesium	24.305

Showing the first 16 of 96 rows and 5 of 5 columns. Cells with formulas show the formula on hover.

	A
1	Molar mass calculator from a chemical formula
2	Notes: what this workbook does, how to use it and the method behind it.
3
4	What it does
5	Adds up the molar mass of a compound from its element counts, with atomic weights looked up from the Elements tab.
6	Shows the mass contribution and mass percent of each element, the number of atoms, and the heaviest element by mass.
7	Includes a mass-to-mole converter for the first compound and a second worked compound.
8
9	How to use it
10	1. On the Calculator tab, type the compound name and formula in the blue cells.
11	2. Enter each element symbol in column A and its count in column B. Use up to 12 rows.
12	3. Read the molar mass, atom count and heaviest element in the tiles at the top.
13	4. Use the converter at the bottom to move between mass in grams and moles.
14	5. To add an element not in the table, add it to the Elements tab in a new row and widen the lookup range.
15
16	Formulas and method

Showing the first 16 of 33 rows and 1 of 1 columns. Cells with formulas show the formula on hover.

What does this template do?

This workbook adds up the molar mass of a chemical compound from the element symbols and counts in its formula. Enter a compound name, its formula and up to twelve element rows. The Calculator tab looks up each atomic weight in the Elements table, multiplies it by the count and totals the mass in grams per mole. It also reports the mass percent of each element, the number of atoms and the heaviest element by mass.

The Elements table lists the abridged IUPAC standard atomic weights for elements 1 to 92. Radioactive elements with no standard atomic weight show the mass number of a long-lived isotope, with a note. A converter block turns a mass in grams into moles and back. A second worked compound, copper(II) sulfate pentahydrate, shows how a hydrate is entered element by element.

The example compound is caffeine, C8H10N4O2, with a molar mass of about 194.19 g/mol. The compound names and masses are example data for the worked case.

What’s inside

Molar mass from element counts, with atomic weights looked up in a table for elements 1 to 92
Mass contribution and mass percent for each element, with a total that sums to 100%
Exact VLOOKUP; an unknown symbol is flagged instead of returning a wrong weight
Grams-to-moles and moles-to-grams converter for the compound on the calculator
Second worked example, copper(II) sulfate pentahydrate, entered as element counts

Which tabs does the workbook have?

Tab	What it holds
Calculator	Compound name, formula, element counts, molar mass, mass percent and a mass-to-mole converter.
Elements	Atomic number, symbol, name and abridged standard atomic weight for elements 1 to 92.
Notes	What the workbook does, the method, assumptions and limits.

What formulas does this template use?

This template holds 111 formulas in 587 cells across 3 tabs, so 19% of its cells calculate. They use 12 distinct functions; the longest formula is 130 characters and 48 of them read from another tab.

Function	Uses	What it does
`IF`	106	one result when a test is true, another when false
`OR`	50	true when any test is true
`IFERROR`	48	swaps an error for a fallback value
`VLOOKUP`	48	looks a value up in a column
`ISNUMBER`	24	true for a number
`NOT`	24	reverses true and false
`SUM`	6	adds numbers
`COUNT`	3	counts numeric cells
`COUNTIF`	2	counts cells meeting one condition
`INDEX`	1	value at a position in a range
`MATCH`	1	position of a value in a range
`MAX`	1	largest value

Counted from the workbook itself. Only functions that Excel, LibreOffice Calc, Google Sheets and Apple Numbers evaluate the same way are used, so the formulas survive every download format.

How do you use it?

On the Calculator tab, type the compound name and formula in the blue cells.
Enter each element symbol in column A and its count in column B, using up to twelve rows.
Read the molar mass, number of atoms and heaviest element in the tiles at the top.
Use the converter block to move between grams and moles for the compound.
For an element that is not in the table, add a row to the Elements tab and extend the lookup range.

What is it good for?

Checking the molar mass of a reagent before weighing it
Converting a sample mass into moles for a reaction
Comparing the mass percent of elements in a hydrate
Teaching how atomic weights add up in a formula

Questions about this sheet

Does the calculator handle hydrates?

Yes. Enter the water of hydration as extra oxygen and hydrogen rows. Copper(II) sulfate pentahydrate is the worked example, with Cu 1, S 1, O 9 and H 10.

Why does a row show Unknown symbol?

The symbol is not in the Elements table. Symbols are matched without regard to case, so enter Co and CO as separate elements rather than as one formula string.

Which atomic weights does it use?

The abridged IUPAC standard atomic weights listed on the Elements tab. The starred radioactive elements show the mass number of a long-lived isotope instead.