Atomic mass units (u) to Grams Converter

How it is calculated

The conversion is a single multiplication: grams = u × 1.66053907×10⁻²⁴ and kilograms = u × 1.66053907×10⁻²⁷, where u is a mass in atomic mass units (daltons). The constant is the mass of one atomic mass unit, one twelfth of a carbon-12 atom. Because the values are tiny, the answer is printed in scientific notation with five significant digits, such as 2.9915e-23, which means 2.9915 × 10⁻²³. The tool applies no limit to the input, so zero returns zero and a negative number returns a negative mass, even though a real mass cannot be negative. The same conversion works for atoms, molecules or sub-atomic particles, as long as you enter the mass in u.

Common mistakes

• Reading the exponent wrongly. 2.9915e-23 is 2.9915 × 10⁻²³, a number with 22 zeros after the decimal point, and not 2.9915 × 10²³.
• Confusing atomic mass units with grams per mole. The numeric value of a molar mass in g/mol equals the mass of one particle in u, but the converter gives the mass of a single particle, not one mole.
• Entering the mass number of an element (an integer) when you need the real atomic mass. Chlorine is about 35.45 u on average, not 35 or 37, because natural samples mix isotopes.
• Typing a space as a thousands separator, as in 1 200. The engine cannot read it and returns no result; type 1200 or 1.2e3.
• Expecting a decimal comma in the Turkish page. The output stays in the form 2.9915e-23 with a decimal point.