Mass and Weight · Unit Converter

Convert Carat (metric) to Attogram

Convert carats (metric) to attograms instantly. 1 carat (metric) = 2e+17 attogram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Attogram to Carat (metric) 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 Last reviewed Updated

Units explained

Troy & Apothecary

Carat (metric)

What is a carat (metric)?

The metric carat (ct) equals exactly 200 milligrams (0.0002 kg).

Origin of the carat (metric)

From Arabic 'qirat' and Greek 'keration', the carob seed once used as a counterweight.

Where it is used

The worldwide standard for gemstone and diamond mass.

When and where it was developed

The metric carat was fixed at 200 mg internationally in 1907.

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.

Carat (metric) to Attogram conversion formula

The relationship between carats (metric) and attograms:

1 ct = 2e+17 ag
1 ag = 5e-18 ct

To convert carats (metric) to attograms, multiply the value in carats (metric) by 2e+17. To reverse, multiply attograms by 5e-18.

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 Carat (metric) converter for the reverse direction.

Step-by-step: convert carats (metric) to attograms

  1. Write down the value in carats (metric) (ct).
  2. Multiply that value by the factor 2e+17.
  3. The product is the equivalent value in attograms (ag).
  4. To reverse, multiply the attogram value by 5e-18.

Worked examples

Example 1 — Convert 1 ct to ag:
1 × 2e+17 = 2e+17 ag

Example 2 — Convert 100 ct to ag:
100 × 2e+17 = 2e+19 ag

Real-world example — Mid-micron to nanometer

3 carats (metric) equals 3,000 attograms — useful when relating mid-infrared wavelengths (typically quoted in microns) to nanometer-scale visible-light wavelength tables.

3 ct × 2e+17 = 6e+17 ag

Real-world example — From microns to sub-micron features

One carat (metric) equals one thousand attograms — the conversion semiconductor designers do constantly when comparing mask feature dimensions to actual transistor gate lengths.

1 ct × 2e+17 = 2e+17 ag

Real-world example — Infrared to visible-spectrum mapping

A 10-carat (metric) thermal infrared wavelength corresponds to a much larger number in attograms, the unit favoured for ultraviolet and visible-light specifications.

10 ct × 2e+17 = 2e+18 ag

Carat (metric) to Attogram conversion table

Standard reference values for converting carats (metric) to attograms:

Carat (metric) [ct]Attogram [ag]
0.012e+15
0.12e+16
12e+17
24e+17
36e+17
48e+17
51e+18
102e+18
204e+18
306e+18
408e+18
501e+19
1002e+19
5001e+20
10002e+20

Frequently asked questions

How many attograms is 1 carat (metric)?
1 carat (metric) equals 2e+17 attogram.
How do I convert carats (metric) to attograms?
Multiply the value in carats (metric) by 2e+17 to get attograms.
How do I convert attograms back to carats (metric)?
Multiply the value in attograms by 5e-18, or use the Attogram to Carat (metric) converter.
How many attograms is 100 carats (metric)?
100 carats (metric) equals 2e+19 attograms, because 100 × 2e+17 = 2e+19.

Convert Carat (metric) to other weight units

Show all Carat (metric) conversions
Metric / SI (18 units)
Avoirdupois (15 units)
Troy & Apothecary (9 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Force / Engineering (5 units)

Sources & references

Conversion factor (1 ct = 2e+17 ag) verified against the following authoritative sources:

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