Mass and Weight · Unit Converter

Convert Grain to Teragram

Convert grains to teragrams instantly. 1 grain = 6.47989e-14 teragram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Teragram to Grain 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

Avoirdupois

Grain

What is a grain?

The grain (gr) equals 1/7000 of an avoirdupois pound, about 64.8 milligrams.

Origin of the grain

Based on the nominal mass of a single barley grain.

Where it is used

Ammunition and bullet mass, archery, and historical pharmacy.

When and where it was developed

Standardized through the English avoirdupois system and retained in 1959.

Metric / SI

Teragram

What is a teragram?

A teragram (Tg) equals 10^9 kilograms, or one million metric tons.

Origin of the teragram

From the SI prefix 'tera-' (from Greek 'teras', monster).

Where it is used

Used in large-scale environmental and industrial mass accounting.

When and where it was developed

The tera- prefix entered the SI in 1960.

Grain to Teragram conversion formula

The relationship between grains and teragrams:

1 gr = 6.47989e-14 Tg

1 Tg = 1.543236e+13 gr

To convert grains to teragrams, multiply the value in grains by 6.47989e-14. To reverse, multiply teragrams by 1.543236e+13.

How to use this converter

Type a value into the calculator. The result in teragrams updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Teragram to Grain converter for the reverse direction.

Step-by-step: convert grains to teragrams

Write down the value in grains (gr).
Multiply that value by the factor 6.47989e-14.
The product is the equivalent value in teragrams (Tg).
To reverse, multiply the teragram value by 1.543236e+13.

Worked examples

Example 1 — Convert 1 gr to Tg:
1 × 6.47989e-14 = 6.47989e-14 Tg

Example 2 — Convert 100 gr to Tg:
100 × 6.47989e-14 = 6.47989e-12 Tg

Real-world example — Hair-width scale measurements

A 70-grain measurement (about the diameter of a human hair) is the kind of value materials engineers regularly express in adjacent micro-scale units like teragrams for direct comparison across supplier datasheets.

70 gr × 6.47989e-14 = 4.535923e-12 Tg

Real-world example — Paper and film thicknesses

At the thickness of office paper (roughly 3 grains), converting between sub-millimeter units is routine for packaging and printing buyers comparing quotes from metric and US suppliers.

3 gr × 6.47989e-14 = 1.943967e-13 Tg

Real-world example — Plastic-film thickness alternates

A 150-grain plastic film converts cleanly to teragrams — useful for packaging buyers reconciling supplier datasheets across metric and US measurement systems.

150 gr × 6.47989e-14 = 9.719835e-12 Tg

Grain to Teragram conversion table

Standard reference values for converting grains to teragrams:

Grain [gr]	Teragram [Tg]
0.01	6.47989e-16
0.1	6.47989e-15
1	6.47989e-14
2	1.295978e-13
3	1.943967e-13
4	2.591956e-13
5	3.239945e-13
10	6.47989e-13
20	1.295978e-12
30	1.943967e-12
40	2.591956e-12
50	3.239945e-12
100	6.47989e-12
500	3.239945e-11
1000	6.47989e-11

Frequently asked questions

How many teragrams is 1 grain?

1 grain equals 6.47989e-14 teragram.

How do I convert grains to teragrams?

Multiply the value in grains by 6.47989e-14 to get teragrams.

How do I convert teragrams back to grains?

Multiply the value in teragrams by 1.543236e+13, or use the Teragram to Grain converter.

How many teragrams is 100 grains?

100 grains equals 6.47989e-12 teragrams, because 100 × 6.47989e-14 = 6.47989e-12.

Convert Grain to other weight units

Show all Grain conversions

Metric / SI (18 units)

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

Avoirdupois (14 units)

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

Troy & Apothecary (10 units)

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

Indian / South Asian (6 units)

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

Scientific / Atomic (9 units)

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

Astronomical (4 units)

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

Biblical / Ancient (14 units)

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

Force / Engineering (5 units)

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

Sources & references

Conversion factor (1 gr = 6.47989e-14 Tg) 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.