Mass and Weight · Unit Converter

Convert Attogram to Quarter (US)

Convert attograms to quarters (us) instantly. 1 attogram = 8.81849e-23 quarter (us) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Quarter (US) to Attogram converter for the reverse conversion.

Written by Sunith Babu L, Ph.D., Lead Engineer Reviewed by Dr. Ashok Kumar K, Ph.D.

Mass and Weight category 2 min read Published June 10, 2026 Last reviewed June 10, 2026 Updated June 10, 2026

Units explained

Metric / SI

Attogram

What is a attogram?

An attogram (ag) equals 10^-21 kilogram.

Origin of the attogram

From the SI prefix 'atto-' (from Danish 'atten', eighteen).

Where it is used

Frontier nanoscience and single-molecule mass detection.

When and where it was developed

The atto- prefix was adopted by the CGPM in 1975.

Avoirdupois

Quarter (US)

What is a quarter (us)?

The US quarter equals one-fourth of a short hundredweight, 25 pounds (about 11.34 kg).

Origin of the quarter (us)

A 'quarter' of the US short hundredweight.

Where it is used

US agricultural and commodity weighing.

When and where it was developed

Defined within the US customary hundredweight system.

Attogram to Quarter (US) conversion formula

The relationship between attograms and quarters (us):

1 ag = 8.81849e-23 qr

1 qr = 1.133981e+22 ag

To convert attograms to quarters (us), multiply the value in attograms by 8.81849e-23. To reverse, multiply quarters (us) by 1.133981e+22.

How to use this converter

Type a value into the calculator. The result in quarters (us) updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Quarter (US) to Attogram converter for the reverse direction.

Step-by-step: convert attograms to quarters (us)

Write down the value in attograms (ag).
Multiply that value by the factor 8.81849e-23.
The product is the equivalent value in quarters (us) (qr).
To reverse, multiply the quarter (us) value by 1.133981e+22.

Worked examples

Example 1 — Convert 1 ag to qr:
1 × 8.81849e-23 = 8.81849e-23 qr

Example 2 — Convert 100 ag to qr:
100 × 8.81849e-23 = 8.81849e-21 qr

Real-world example — Molecular dimensions

The diameter of small molecular structures (around 2 attograms) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.

2 ag × 8.81849e-23 = 1.763698e-22 qr

Real-world example — Wavelengths across the spectrum

Optical and atomic-scale phenomena are routinely cross-converted between sub-micron units. A photon of wavelength 800 attograms can be re-expressed in quarters (us) for direct comparison with another instrument's calibration data sheet.

800 ag × 8.81849e-23 = 7.054792e-20 qr

Attogram to Quarter (US) conversion table

Standard reference values for converting attograms to quarters (us):

Attogram [ag]	Quarter (US) [qr]
0.01	8.81849e-25
0.1	8.81849e-24
1	8.81849e-23
2	1.763698e-22
3	2.645547e-22
4	3.527396e-22
5	4.409245e-22
10	8.81849e-22
20	1.763698e-21
30	2.645547e-21
40	3.527396e-21
50	4.409245e-21
100	8.81849e-21
500	4.409245e-20
1000	8.81849e-20

Frequently asked questions

How many quarters (us) is 1 attogram?

1 attogram equals 8.81849e-23 quarter (us).

How do I convert attograms to quarters (us)?

Multiply the value in attograms by 8.81849e-23 to get quarters (us).

How do I convert quarters (us) back to attograms?

Multiply the value in quarters (us) by 1.133981e+22, or use the Quarter (US) to Attogram converter.

How many quarters (us) is 100 attograms?

100 attograms equals 8.81849e-21 quarters (us), because 100 × 8.81849e-23 = 8.81849e-21.

Convert Attogram to other weight units

Show all Attogram conversions

Metric / SI (17 units)

Attogram to Femtogram (fg) Attogram to Picogram (pg) Attogram to Nanogram (ng) Attogram to Microgram (µg) Attogram to Milligram (mg) Attogram to Centigram (cg) Attogram to Decigram (dg) Attogram to Gram (g) Attogram to Dekagram (dag) Attogram to Hectogram (hg) Attogram to Kilogram (kg) Attogram to Quintal (metric) (q) Attogram to Metric Ton (t) Attogram to Gigagram (Gg) Attogram to Teragram (Tg) Attogram to Petagram (Pg) Attogram to Exagram (Eg)

Avoirdupois (15 units)

Attogram to Grain (gr) Attogram to Dram (avoirdupois) (dr) Attogram to Ounce (oz) Attogram to Pound (lb) Attogram to Clove (clove) Attogram to Stone (US) (st) Attogram to Stone (UK) (st) Attogram to Quarter (US) (qr) Attogram to Quarter (UK) (qr) Attogram to Hundredweight (US) (cwt) Attogram to Hundredweight (UK) (cwt) Attogram to Wey (wey) Attogram to Kilopound (kip) (kip) Attogram to Ton (short, US) (sh tn) Attogram to Ton (long, UK) (long tn)

Troy & Apothecary (10 units)

Attogram to Point (1/100 carat) (pt) Attogram to Carat (metric) (ct) Attogram to Scruple (apothecary) (s ap) Attogram to Pennyweight (dwt) Attogram to Momme (mom) Attogram to Mace (mace) Attogram to Dram (apothecary/troy) (dr ap) Attogram to Troy Ounce (oz t) Attogram to Tael (tael) Attogram to Pound (troy/apothecary) (lb t)

Indian / South Asian (6 units)

Attogram to Ratti (ratti) Attogram to Masha (masha) Attogram to Tola (tola) Attogram to Chittack (Chatank) (chittack) Attogram to Seer (Ser) (seer) Attogram to Maund (Mann) (maund)

Scientific / Atomic (9 units)

Attogram to Electron Mass (rest) (me) Attogram to MeV/c2 (MeV/c²) Attogram to Muon Mass (mµ) Attogram to Atomic Mass Unit (u) Attogram to Proton Mass (mp) Attogram to Neutron Mass (mn) Attogram to Deuteron Mass (md) Attogram to Carbon-12 Atom Mass (C-12) Attogram to Planck Mass (mP)

Astronomical (4 units)

Attogram to Lunar Mass (Moon) (M☾) Attogram to Earth's Mass (M⊕) Attogram to Jupiter Mass (MJ) Attogram to Sun's Mass (M☉)

Biblical / Ancient (14 units)

Attogram to Lepton (Biblical Roman) (lepton) Attogram to Quadrans (Biblical Roman) (quadrans) Attogram to Assarion (Biblical Roman) (assarion) Attogram to Gerah (Biblical Hebrew) (gerah) Attogram to Drachma (Biblical Greek) (drachma) Attogram to Denarius (Biblical Roman) (denarius) Attogram to Bekan (Biblical Hebrew) (bekah) Attogram to Didrachma (Biblical Greek) (didrachma) Attogram to Shekel (Biblical Hebrew) (shekel) Attogram to Tetradrachma (Biblical Greek) (tetra) Attogram to Mina (Biblical Greek) (mina) Attogram to Mina (Biblical Hebrew) (mina) Attogram to Talent (Biblical Greek) (talent) Attogram to Talent (Biblical Hebrew) (talent)

Force / Engineering (5 units)

Attogram to Poundal (pdl) Attogram to Ton (assay) (US) (AT) Attogram to Ton (assay) (UK) (AT) Attogram to Kilogram-force square second/meter (hyl) Attogram to Slug (slug)

Sources & references

Conversion factor (1 ag = 8.81849e-23 qr) 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.

Results are provided for general reference. Verify critical measurements against an authoritative standard.