Mass and Weight · Unit Converter

Convert Gram to Milligram

Convert grams to milligrams instantly. 1 gram = 1000 milligram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Milligram to Gram 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

Metric / SI

Gram

What is a gram?

The gram (g) equals one-thousandth of a kilogram.

Origin of the gram

From Late Latin 'gramma', a small weight or scruple.

Where it is used

The everyday metric unit for food, medicine, and small objects.

When and where it was developed

Defined in 1795 as the mass of one cubic centimeter of water at melting point.

Metric / SI

Milligram

What is a milligram?

A milligram (mg) equals one-millionth of a kilogram, or 0.001 gram.

Origin of the milligram

From the SI prefix 'milli-' (from Latin 'mille', thousand).

Where it is used

Standard for medicine dosing, nutrition labels, and fine jewelry.

When and where it was developed

Part of the original metric system of 1795.

Gram to Milligram conversion formula

The relationship between grams and milligrams:

1 g = 1000 mg
1 mg = 0.001 g

To convert grams to milligrams, multiply the value in grams by 1000. To reverse, multiply milligrams by 0.001.

How to use this converter

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

Step-by-step: convert grams to milligrams

  1. Write down the value in grams (g).
  2. Multiply that value by the factor 1000.
  3. The product is the equivalent value in milligrams (mg).
  4. To reverse, multiply the milligram value by 0.001.

Worked examples

Example 1 — Convert 1 g to mg:
1 × 1000 = 1000 mg

Example 2 — Convert 100 g to mg:
100 × 1000 = 100000 mg

Real-world example — Adjacent small-scale precision

One gram equals 1,000 milligrams — the standard sub-millimeter precision conversion that materials engineers use whenever they switch between bulk material thickness specs (larger unit) and surface-finish characteristics (smaller unit).

1 g × 1000 = 1000 mg

Real-world example — Adjacent metric sub-units

One gram equals 1,000 milligrams. Engineers move between these scales constantly: PCB feature sizes in the larger unit, wire-bond diameters in the smaller.

1 g × 1000 = 1000 mg

Gram to Milligram conversion table

Standard reference values for converting grams to milligrams:

Gram [g]Milligram [mg]
0.0110
0.1100
11000
22000
33000
44000
55000
1010000
2020000
3030000
4040000
5050000
100100000
500500000.0000000001
10001000000.0000000001

Frequently asked questions

How many milligrams is 1 gram?
1 gram equals 1000 milligram.
How do I convert grams to milligrams?
Multiply the value in grams by 1000 to get milligrams.
How do I convert milligrams back to grams?
Multiply the value in milligrams by 0.001, or use the Milligram to Gram converter.
How many milligrams is 100 grams?
100 grams equals 100000 milligrams, because 100 × 1000 = 100000.

Convert Gram to other weight units

Show all Gram conversions
Metric / SI (17 units)
Gram to Attogram (ag) Gram to Femtogram (fg) Gram to Picogram (pg) Gram to Nanogram (ng) Gram to Microgram (µg) Gram to Milligram (mg) Gram to Centigram (cg) Gram to Decigram (dg) Gram to Dekagram (dag) Gram to Hectogram (hg) Gram to Kilogram (kg) Gram to Quintal (metric) (q) Gram to Metric Ton (t) Gram to Gigagram (Gg) Gram to Teragram (Tg) Gram to Petagram (Pg) Gram to Exagram (Eg)
Avoirdupois (15 units)
Gram to Grain (gr) Gram to Dram (avoirdupois) (dr) Gram to Ounce (oz) Gram to Pound (lb) Gram to Clove (clove) Gram to Stone (US) (st) Gram to Stone (UK) (st) Gram to Quarter (US) (qr) Gram to Quarter (UK) (qr) Gram to Hundredweight (US) (cwt) Gram to Hundredweight (UK) (cwt) Gram to Wey (wey) Gram to Kilopound (kip) (kip) Gram to Ton (short, US) (sh tn) Gram to Ton (long, UK) (long tn)
Troy & Apothecary (10 units)
Gram to Point (1/100 carat) (pt) Gram to Carat (metric) (ct) Gram to Scruple (apothecary) (s ap) Gram to Pennyweight (dwt) Gram to Momme (mom) Gram to Mace (mace) Gram to Dram (apothecary/troy) (dr ap) Gram to Troy Ounce (oz t) Gram to Tael (tael) Gram to Pound (troy/apothecary) (lb t)
Indian / South Asian (6 units)
Gram to Ratti (ratti) Gram to Masha (masha) Gram to Tola (tola) Gram to Chittack (Chatank) (chittack) Gram to Seer (Ser) (seer) Gram to Maund (Mann) (maund)
Scientific / Atomic (9 units)
Gram to Electron Mass (rest) (me) Gram to MeV/c2 (MeV/c²) Gram to Muon Mass (mµ) Gram to Atomic Mass Unit (u) Gram to Proton Mass (mp) Gram to Neutron Mass (mn) Gram to Deuteron Mass (md) Gram to Carbon-12 Atom Mass (C-12) Gram to Planck Mass (mP)
Astronomical (4 units)
Gram to Lunar Mass (Moon) (M☾) Gram to Earth's Mass (M⊕) Gram to Jupiter Mass (MJ) Gram to Sun's Mass (M☉)
Biblical / Ancient (14 units)
Gram to Lepton (Biblical Roman) (lepton) Gram to Quadrans (Biblical Roman) (quadrans) Gram to Assarion (Biblical Roman) (assarion) Gram to Gerah (Biblical Hebrew) (gerah) Gram to Drachma (Biblical Greek) (drachma) Gram to Denarius (Biblical Roman) (denarius) Gram to Bekan (Biblical Hebrew) (bekah) Gram to Didrachma (Biblical Greek) (didrachma) Gram to Shekel (Biblical Hebrew) (shekel) Gram to Tetradrachma (Biblical Greek) (tetra) Gram to Mina (Biblical Greek) (mina) Gram to Mina (Biblical Hebrew) (mina) Gram to Talent (Biblical Greek) (talent) Gram to Talent (Biblical Hebrew) (talent)
Force / Engineering (5 units)
Gram to Poundal (pdl) Gram to Ton (assay) (US) (AT) Gram to Ton (assay) (UK) (AT) Gram to Kilogram-force square second/meter (hyl) Gram to Slug (slug)

Sources & references

Conversion factor (1 g = 1000 mg) verified against the following authoritative sources:

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