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Milligrams to Grams (mg to g)

Convert milligrams to grams: 1 mg = 0.001 g. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

Formula

1 mg = 0.001 g

grams = milligrams × 0.001 — reverse: milligrams = grams × 1000

The factor is derived from the SI definitions of both units (base unit: kg) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.

Worked examples

5 mg = 0.005 g
12.5 mg = 0.0125 g
100 mg = 0.1 g

Milligrams to grams conversion table

Milligrams (mg)	Grams (g)
1	0.001
2	0.002
3	0.003
4	0.004
5	0.005
6	0.006
7	0.007
8	0.008
9	0.009
10	0.01
15	0.015
20	0.02
25	0.025
30	0.03
40	0.04
50	0.05
75	0.075
100	0.1
200	0.2
250	0.25
500	0.5
1000	1

FAQ

How many grams are in one milligram?

1 mg = 0.001 g. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

What is the formula to convert milligrams to grams?

Multiply the value in milligrams by 0.001: grams = milligrams × 0.001. For example, 5 mg = 0.005 g.

How do I convert grams back to milligrams?

Multiply by the inverse factor 1000 (milligrams = grams × 1000), or use the grams-to-milligrams page.

Related conversions

Grams to milligrams (reverse)
Mass / Weight Converter — all mass units in one tool
Kilograms to Pounds
Pounds to Kilograms
Grams to Ounces
Ounces to Grams
Kilograms to Stone
Stone to Kilograms
Pounds to Ounces
Ounces to Pounds

Machine access

API: GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=mg&to_unit=g
MCP: server https://tttkmbb.com/mcp, tool convert_units with {"value":5,"from_unit":"mg","to_unit":"g"}
Markdown: https://tttkmbb.com/conversion/mg-to-grams.md · JSON: https://tttkmbb.com/conversion/mg-to-grams.json (add ?value= for a result) · Units: /api/v1/units?quantity=mass
OpenAPI operationId: convert_units. Freshness: static. Authentication: none.