Mass and Weight · Unit Converter

Convert Femtogram to Ton (assay) (US)

Convert femtograms to tons (assay) (us) instantly. 1 femtogram = 3.428571e-17 ton (assay) (us) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Ton (assay) (US) to Femtogram 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

Femtogram

What is a femtogram?

A femtogram (fg) equals 10^-18 kilogram.

Origin of the femtogram

From the SI prefix 'femto-' (from Danish/Norwegian 'femten', fifteen).

Where it is used

Nanotechnology and high-sensitivity mass spectrometry.

When and where it was developed

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

Force / Engineering

Ton (assay) (US)

What is a ton (assay) (us)?

The assay ton (US) equals about 29.167 grams, a mining-assay convenience unit.

Origin of the ton (assay) (us)

Devised so an assay sample's metal in milligrams reads as troy ounces per short ton.

Where it is used

Ore assaying and metallurgy.

When and where it was developed

Adopted in assay laboratories to simplify ore-grade calculation.

Femtogram to Ton (assay) (US) conversion formula

The relationship between femtograms and tons (assay) (us):

1 fg = 3.428571e-17 AT

1 AT = 2.916667e+16 fg

To convert femtograms to tons (assay) (us), multiply the value in femtograms by 3.428571e-17. To reverse, multiply tons (assay) (us) by 2.916667e+16.

How to use this converter

Type a value into the calculator. The result in tons (assay) (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 Ton (assay) (US) to Femtogram converter for the reverse direction.

Step-by-step: convert femtograms to tons (assay) (us)

Write down the value in femtograms (fg).
Multiply that value by the factor 3.428571e-17.
The product is the equivalent value in tons (assay) (us) (AT).
To reverse, multiply the ton (assay) (us) value by 2.916667e+16.

Worked examples

Example 1 — Convert 1 fg to AT:
1 × 3.428571e-17 = 3.428571e-17 AT

Example 2 — Convert 100 fg to AT:
100 × 3.428571e-17 = 3.428571e-15 AT

Real-world example — From wavelengths to millimeter-scale objects

A value of one million femtograms sounds vast at the atomic scale but converts to a small everyday quantity in tons (assay) (us) — useful when relating optical-wavelength specifications to physical mounting hardware.

1000000 fg × 3.428571e-17 = 3.428571e-11 AT

Real-world example — Sub-micron to millimeter

500,000 femtograms converts to a small everyday quantity in tons (assay) (us) — useful when relating optical-wavelength specifications to physical mounting hardware.

500000 fg × 3.428571e-17 = 1.714286e-11 AT

Femtogram to Ton (assay) (US) conversion table

Standard reference values for converting femtograms to tons (assay) (us):

Femtogram [fg]	Ton (assay) (US) [AT]
0.01	3.428571e-19
0.1	3.428571e-18
1	3.428571e-17
2	6.857142e-17
3	1.028571e-16
4	1.371428e-16
5	1.714286e-16
10	3.428571e-16
20	6.857142e-16
30	1.028571e-15
40	1.371428e-15
50	1.714286e-15
100	3.428571e-15
500	1.714286e-14
1000	3.428571e-14

Frequently asked questions

How many tons (assay) (us) is 1 femtogram?

1 femtogram equals 3.428571e-17 ton (assay) (us).

How do I convert femtograms to tons (assay) (us)?

Multiply the value in femtograms by 3.428571e-17 to get tons (assay) (us).

How do I convert tons (assay) (us) back to femtograms?

Multiply the value in tons (assay) (us) by 2.916667e+16, or use the Ton (assay) (US) to Femtogram converter.

How many tons (assay) (us) is 100 femtograms?

100 femtograms equals 3.428571e-15 tons (assay) (us), because 100 × 3.428571e-17 = 3.428571e-15.

Convert Femtogram to other weight units

Show all Femtogram conversions

Metric / SI (17 units)

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

Avoirdupois (15 units)

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

Troy & Apothecary (10 units)

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

Indian / South Asian (6 units)

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

Scientific / Atomic (9 units)

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

Astronomical (4 units)

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

Biblical / Ancient (14 units)

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

Force / Engineering (5 units)

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

Sources & references

Conversion factor (1 fg = 3.428571e-17 AT) 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.

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