Convert Hectogram to Attogram
Convert hectograms to attograms instantly. 1 hectogram = 1e+20 attogram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Attogram to Hectogram converter for the reverse conversion.
Units explained
Hectogram
A hectogram (hg) equals 0.1 kilogram, or 100 grams.
From the SI prefix 'hecto-' (from Greek 'hekaton', hundred).
Common in continental European food retail, especially Italy ('etto').
The hecto- prefix dates to the original metric system of 1795.
Attogram
An attogram (ag) equals 10^-21 kilogram.
From the SI prefix 'atto-' (from Danish 'atten', eighteen).
Frontier nanoscience and single-molecule mass detection.
The atto- prefix was adopted by the CGPM in 1975.
Hectogram to Attogram conversion formula
The relationship between hectograms and attograms:
To convert hectograms to attograms, multiply the value in hectograms by 1e+20. To reverse, multiply attograms by 1e-20.
How to use this converter
Type a value into the calculator. The result in attograms updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Attogram to Hectogram converter for the reverse direction.
Step-by-step: convert hectograms to attograms
- Write down the value in hectograms (hg).
- Multiply that value by the factor 1e+20.
- The product is the equivalent value in attograms (ag).
- To reverse, multiply the attogram value by 1e-20.
Worked examples
Example 1 — Convert 1 hg to ag:
1 × 1e+20 = 1e+20 ag
Example 2 — Convert 100 hg to ag:
100 × 1e+20 = 1e+22 ag
Real-world example — Human-scale to atomic dimensions
One hectogram equals one billion attograms — the canonical metric conversion bridging everyday objects and atomic-scale features in physics, chemistry, and electronics.
1 hg × 1e+20 = 1e+20 ag
Real-world example — Meter to nanoscale
One hectogram equals one billion attograms. Physics curricula use this conversion to teach orders of magnitude when introducing the electromagnetic spectrum.
1 hg × 1e+20 = 1e+20 ag
Hectogram to Attogram conversion table
Standard reference values for converting hectograms to attograms:
| Hectogram [hg] | Attogram [ag] |
|---|---|
| 0.01 | 1e+18 |
| 0.1 | 1e+19 |
| 1 | 1e+20 |
| 2 | 2e+20 |
| 3 | 3e+20 |
| 4 | 4e+20 |
| 5 | 5e+20 |
| 10 | 1e+21 |
| 20 | 2e+21 |
| 30 | 3e+21 |
| 40 | 4e+21 |
| 50 | 5e+21 |
| 100 | 1e+22 |
| 500 | 5e+22 |
| 1000 | 1e+23 |
Frequently asked questions
How many attograms is 1 hectogram?
How do I convert hectograms to attograms?
How do I convert attograms back to hectograms?
How many attograms is 100 hectograms?
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Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 hg = 1e+20 ag) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.