What Is picogram?
A picogram is a unit used to measure very small amounts of mass. It is part of the metric system. One picogram is equal to one trillionth of a gram. Scientists use picograms when the amount of material is far too small to see with your eyes, such as DNA, viruses, and tiny particles in the air.
Definition
A picogram is a unit of mass in the International System of Units prefix family. It is based on the gram.
- 1 picogram (pg) = 0.000000000001 gram (g)
- In scientific notation, 1 picogram = 1 × 10−12 gram
This means you would need 1 000 000 000 000 picograms to make just one gram.
History / Origin
The word picogram is made from two parts.
- Pico is a metric prefix that means 10−12, or one trillionth.
- Gram is the basic metric unit for mass.
The prefix pico was officially added to the metric system in the 1960s as science and technology improved. Researchers began to work with smaller and smaller amounts of matter, especially in chemistry, physics, and biology. They needed words and symbols for these tiny sizes, so pico became the standard name for 10−12. From that time, units like picogram and picometer became common in scientific writing.
Symbol & Abbreviation
The picogram has a short symbol used in formulas, tables, and on lab reports.
- Full name: picogram
- Symbol: pg
Note that the letter p is lowercase. This is important. A capital P would mean something different in science. When you see a number followed by pg it means that number of picograms.
Current Use Around the World
Picograms are used almost only in science and medicine. They are not used in daily life like grams or kilograms, because the amounts are too small.
Some common uses are:
- Biology and genetics: measuring DNA and RNA, the amount of genetic material in a cell, or the mass of single cells or viruses.
- Medicine and blood tests: reporting levels of hormones, vitamins, and other chemicals in blood, where the amounts are extremely tiny.
- Environmental science: tracking tiny amounts of pollutants or metals in air, water, or soil.
- Nanotechnology and materials science: measuring the mass of nanoparticles or very small fibers.
Scientists all over the world use picograms because the metric system is international. This makes it easier to share data and compare results between laboratories and countries.
Example Conversions
Here are some helpful conversions between picograms and other mass units.
Picograms to grams
- 1 picogram = 0.000000000001 gram
- 1 gram = 1 000 000 000 000 picograms
Picograms to nanograms
A nanogram is 10−9 gram. It is 1000 times larger than a picogram.
- 1 picogram = 0.001 nanogram (ng)
- 1 nanogram = 1000 picograms
Picograms to micrograms
A microgram is 10−6 gram. It is 1 000 000 times larger than a picogram.
- 1 picogram = 0.000001 microgram (µg)
- 1 microgram = 1 000 000 picograms
Everyday style comparisons
- A grain of table salt weighs around 60 000 000 000 picograms or more.
- The DNA in a single human cell is about a few picograms.
- Some hormones in your blood are present in only a few picograms per milliliter.
Related Units
Picogram is part of a family of metric mass units based on the gram. Here are closely related ones, from larger to smaller.
- Kilogram (kg): 1 kg = 1000 g = 1 000 000 000 000 000 000 pg
- Gram (g): basic metric mass unit
- Milligram (mg): 1 mg = 0.001 g = 1 000 000 000 pg
- Microgram (µg): 1 µg = 0.000001 g = 1 000 000 000 000 pg
- Nanogram (ng): 1 ng = 0.000000001 g = 1 000 000 000 pg
- Picogram (pg): 1 pg = 0.000000000001 g
- Femtogram (fg): 1 fg = 0.000000000000001 g = 0.001 pg
In atomic physics and chemistry, another mass unit is also used.
- Atomic mass unit (u or dalton Da): used to describe masses of atoms and molecules. One picogram equals about 6 × 1011 atomic mass units.
FAQs
How small is a picogram really?
A picogram is extremely small. It is one trillionth of a gram. If you divided one gram into 1 000 000 000 000 equal pieces, each piece would weigh one picogram.
Where would I see picograms used?
You will mainly see picograms in scientific papers, lab reports, and medical test results. For example, a blood test might report hormone levels in picograms per milliliter.
Why not just use grams for everything?
Using grams for tiny amounts would give very long decimal numbers that are hard to read. Picograms let scientists write clear and simple numbers for very small masses.
Is picogram an SI unit?
The base SI unit for mass is the kilogram. The gram and its multiples and submultiples, such as milligram, microgram, nanogram, and picogram, are accepted for use with SI and follow the same rules.
Can normal scales measure picograms?
No. Regular kitchen or bathroom scales cannot measure anything as small as a picogram. Special high precision instruments in laboratories, such as microbalances and advanced sensors, are needed to detect such small masses.
What is the difference between pg and ng?
Pg means picogram and ng means nanogram. One nanogram is 1000 times larger than one picogram. So 1 ng = 1000 pg, and 1 pg = 0.001 ng.
Is picogram used outside of science?
Picogram is almost never used in everyday life. It is mainly a scientific and medical unit because the masses involved are far too small to feel or see directly.