Petagram to Attogram

The attogram is a unit of mass equal to 10⁻¹⁸ grams or 10⁻²¹ kilograms — one quintillionth of a gram.

1 ag = 10⁻¹⁸ g = 10⁻²¹ kg. A single HIV virus has a mass of about 10¹⁰ ag.

To convert ag to kg: multiply by 10⁻²¹. To convert kg to ag: multiply by 10²¹.

Measuring masses of individual nanoparticles, viruses, and large biomolecules in nanosensor research.

In 2012, researchers achieved single-proton sensitivity (1.67 × 10⁻⁶ ag) using carbon nanotube resonators.

Confusing atto (10⁻¹⁸) with femto (10⁻¹⁵) — they differ by a factor of 1,000.

Follow the prefix chain down: milli, micro, nano, pico, femto, atto — each step is 1,000× smaller.