nmi to km: 1 nmi = 1.852 km (exact)

The formula

km = nmi × 1.852

Where the factor comes from — each unit by its definition, then its size in SI:

1 nmi = 1852 × m = 1,852 m
1 km = 1000 × m = 1,000 m

Dividing the two SI sizes gives the factor: 1.852, exact — every step above is a definition, not a measurement. The reverse factor is 0.539956803456.

Every formula on this site takes lengths in metres. Heights, distances and stopping distances quoted in feet, inches or miles have to be converted first — getting it wrong by a factor of 3.28 is the most common unit slip in homework.

Worked examples

A sprint track straight (100 m): 0.0539957 nmi = 0.1 km — 0.0539957 × 1.852 = 0.1
A marathon: 22.7835 nmi = 42.195 km — 22.7835 × 1.852 = 42.195
A tall doorway (6 ft): 0.000987473 nmi = 0.0018288 km — 0.000987473 × 1.852 = 0.0018288
A school ruler (30 cm): 0.000161987 nmi = 0.0003 km — 0.000161987 × 1.852 = 0.0003

Frequently asked questions

How many kilometres is 1 nmi?

1 nmi = 1.852 km, exactly, from the unit definitions.

How do I convert kilometres back to nautical miles?

Divide by 1.852 — or multiply by 0.539956803456: 1 km = 0.539956803456 nmi.

nmi to km conversion table

Nautical miles (nmi)	Kilometres (km)
1	1.852
2	3.704
3	5.556
4	7.408
5	9.26
6	11.112
7	12.964
8	14.816
9	16.668
10	18.52
15	27.78
20	37.04
25	46.3
30	55.56
40	74.08
50	92.6
60	111.12
70	129.64
75	138.9
80	148.16
90	166.68
100	185.2
150	277.8
200	370.4
250	463
500	926
1,000	1,852

Definitions: BIPM, The International System of Units (SI Brochure), 9th edition (2019), Tables 2, 4 and 8 — https://www.bipm.org/en/publications/si-brochure. Machine value of the factor: 1.852.