What Is a Femtomole (fmol)? Definition, Conversion, Uses & Examples

The femtomole (symbol: fmol) is an SI-prefixed unit of amount of substance equal to 10⁻¹⁵ mole. It is widely used to measure extremely small quantities of chemical substances in modern laboratories. Scientists working in analytical chemistry, molecular biology, pharmaceutical research, nanotechnology, and biotechnology frequently report measurements in femtomoles because it provides a convenient way to express trace amounts of molecules.

To understand how femtomoles relate to other SI units, see our guide to Amount of Substance.

Definition

A femtomole is one quadrillionth of a mole:

• 1 femtomole = 10⁻¹⁵ mole
• Symbol: fmol
• SI Prefix: femto-

The femtomole measures the amount of substance rather than mass or volume. Like the mole, it counts elementary entities such as atoms, molecules, ions, electrons, or other specified particles.

History and Origin

The femtomole is derived by combining the SI prefix femto- with the mole, the SI base unit for amount of substance. The SI prefix femto represents 10⁻¹⁵. The mole became an SI base unit in 1971 and has been defined since 2019 using the fixed numerical value of the Avogadro constant, ensuring precise and internationally consistent measurements.

Where Is Femtomole Used?

Although not encountered in everyday measurements, femtomoles are commonly used in high-precision scientific fields, including:

• Mass spectrometry
• Liquid chromatography (LC)
• Proteomics
• Genomics
• DNA and RNA sequencing
• Clinical diagnostics
• Drug discovery
• Biotechnology research
• Analytical chemistry

Practical Applications

Researchers frequently measure DNA fragments, proteins, peptides, antibodies, metabolites, and trace chemicals in femtomoles. Modern laboratory instruments can accurately detect and quantify substances at this scale, making the unit valuable for medical diagnostics, pharmaceutical quality control, forensic science, and environmental testing.

Relationship to Other Units

• 1 femtomole = 1,000 attomoles
• 1 femtomole = 0.001 picomole
• 1 picomole = 1,000 femtomoles
• 1 nanomole = 1,000,000 femtomoles
• 1 micromole = 1,000,000,000 femtomoles
• 1 millimole = 1,000,000,000,000 femtomoles
• 1 mole = 1,000,000,000,000,000 femtomoles

Related Unit Conversions

• Femtomole to Mole
• Mole to Femtomole
• Femtomole to Attomole
• Femtomole to Picomole
• Femtomole to Nanomole
• Femtomole to Micromole
• Femtomole to Millimole

Real-World Examples

A laboratory analyzing DNA may detect only a few femtomoles of genetic material in a biological sample. Likewise, highly sensitive mass spectrometers often report proteins and peptides in femtomoles because the measured quantities are far too small to express conveniently in whole moles.

Frequently Asked Questions

What is a femtomole?

A femtomole is an SI-prefixed unit of amount of substance equal to 10⁻¹⁵ mole.

What is the symbol for femtomole?

The SI symbol for femtomole is fmol.

How many femtomoles are in one mole?

One mole contains exactly 10¹⁵ femtomoles.

Where is the femtomole used?

Femtomoles are commonly used in analytical chemistry, molecular biology, pharmaceutical research, biotechnology, genomics, proteomics, and clinical laboratories.

Is femtomole an SI unit?

Yes. The femtomole is an SI-prefixed decimal multiple of the mole and follows the International System of Units (SI).

External References

• Wikipedia – Mole (unit)
• NIST – SI Units: Amount of Substance
• BIPM – International System of Units (SI)

Conclusion

The femtomole is an essential unit for expressing extremely small amounts of substance in scientific research. It provides a practical way to report molecular quantities in chemistry, biology, medicine, and pharmaceutical analysis while remaining fully compatible with the International System of Units. Understanding the femtomole and its relationship to other SI units helps researchers accurately interpret laboratory measurements and convert between different scales of amount of substance.