How many square kilometers are in a square mile?

2.589988110336 km² exactly, which this page prints as 2.58998811034 at twelve significant digits. The multiplication scales cleanly: 0.5 mi² is 1.29499405517 km², 2 mi² is 5.17997622067 km², 5 mi² is 12.9499405517 km², 10 mi² is 25.8998811034 km², 100 mi² is 258.998811034 km² and 1,000 mi² is 2,589.98811034 km².

What is the formula for square miles to square kilometers?

Use km² = mi² × 2.589988110336 with the exact international factor. In reverse use mi² = km² / 2.589988110336; multiplying by the rounded reciprocal 0.386102158542 is an approximation. One km² displays as 0.386102158542 mi², 100 km² as 38.6102158542 mi² and 500 km² as 193.051079271 mi². Swap units reverses the pair.

Why is the factor 2.59 and not 1.609344?

Area scales with the square of the length factor: an international mile is exactly 1.609344 km, and 1.609344² = 2.589988110336 exactly. The exact inverse area factor is (1 / 1.609344)² and displays as 0.386102158542 mi² per km². A length readout of 0.621371192237 mi per km is rounded; squaring that displayed decimal is a further approximation.

How many acres and square feet are in a square mile?

Exactly 640 acres and exactly 27,878,400 square feet, both of which sit in the list under the answer, along with 3,097,600 square yards, 4,014,489,600 square inches, 258.998811034 hectares and 2,589,988.11034 square metres. Those whole numbers are not rounding: the acre, the foot and the mile are defined against each other, so an acre comes back as 0.0015625 mi² with nothing left over.

Which mile is it, the international mile or the US survey mile?

This menu uses the international mile of exactly 1,609.344 m, so 1 mi² displays as 2.58998811034 km². For an explicitly supplied survey definition of 5,280 × (1200/3937) m per mile, the exact squared factor differs and is about 2.58999847032 km², roughly 10.36 m² larger per square mile. Survey mile is absent here. Confirm the source’s definition; geography or property type alone does not identify it, and the converter does not decide whether the difference meets a task’s requirements.

How big is a section or a township in square kilometers?

Those names do not establish the measured area or mile convention. If a source explicitly supplies 1 international square mile, it is exactly 640 international acres and displays as 2.58998811034 km². A supplied 36 international square miles displays as 93.2395719721 km². You can also select Acre in From for a supplied international-acre quantity. The converter does not interpret a land record or infer its boundaries.

Where do the units sit in the list under the answer?

The list shows every other unit in the area category and leaves out the one you are converting from, so here it reads square centimetre, square metre, hectare, square kilometre, square inch, square foot, square yard and acre, with the square kilometre appearing both as the headline and as a row. The readout strip carries an Uncommon units switch labelled Show 1 more, which adds the square millimetre: one square mile is 2,589,988,110,340 mm².

Why does the page open on square miles and square kilometres when I last converted something else?

This focused page opens on Square mile (mi²) to Square kilometer (km²), while preserving the main converter’s saved unit pair. When storage is usable, a saved value and uncommon-unit preference can travel between pages. Its suffix must still match From. Valid deliberate scalar edits can save those fields after a short delay; invalid or incomplete drafts preserve the saved record. Unusable or conflicting records remain until you use Forget saved settings, which keeps the current conversion on screen. Your input and converted values are calculated in the browser and are not uploaded by the converter. The definitions arrive with the page, so conversion needs no external data lookup and keeps working offline after the page has loaded. The core conversion needs no account. Copy result copies the displayed headline without digit-grouping commas; each visible conversion row has its own Copy button. Displayed and copied values round to twelve significant digits. If native copying fails, a complete selectable summary identifies the input, selected pair and conventions and includes every unit in the category, including uncommon units.

Square Miles to Square Kilometers Converter

A mile is exactly 1,609.344 metres, so a square mile is exactly 2,589,988.110336 square metres, which is 2.589988110336 square kilometres. The area factor is the length factor squared, which is why a figure near 1.6 turns into one near 2.59 rather than staying where you expect it. Answers here print to twelve significant digits, so 1 mi² reads 2.58998811034 km², with rounding at the twelfth significant digit. From there it scales: 3 mi² is 7.76996433101 km², 10 mi² is 25.8998811034 km², 50 mi² is 129.499405517 km², 100 mi² is 258.998811034 km² and 1,000 mi² is 2,589.98811034 km². Going back the other way a square kilometre is 0.386102158542 square miles. This page opens the converter with Square mile (mi²) in the From box and Square kilometer (km²) in the To box, ahead of whatever pair you converted last, and the list under the answer carries the same area in square centimetres, square metres, hectares, square inches, square feet, square yards and acres, so one square mile also reads 258.998811034 ha, 2,589,988.11034 m², 27,878,400 ft², 3,097,600 yd² and exactly 640 acres.

From

To2.58998811034

Category: Area

Base unit: square meter

Uncommon units: Show 1 more

Foot-based areas use the international foot: one acre is 4,046.8564224 square meters. Historical US survey-foot areas require a different convention.

Results round to 12 significant digits using the listed unit definitions. Input must have a finite numeric magnitude and at most 512 significant digits. Type a single decimal or scientific number; a matching From unit suffix is accepted. Commas and grouped spaces separate thousands; decimal commas, fractions and compound measurements are refused.

1 mi² in every area unit

Square centimetercm²
25,899,881,103.4
Square meterm²
2,589,988.11034
Hectareha
258.998811034
Square kilometerkm²
2.58998811034
Square inchin²
4,014,489,600
Square footft²
27,878,400
Square yardyd²
3,097,600
Acreac
640

Selectable complete conversion

Unit Converter — Area
Input: 1 (Square mile, mi²)
Result: 2.58998811034 km² (Square kilometer)
Displayed values round to 12 significant digits.
Foot-based areas use the international foot: one acre is 4,046.8564224 square meters. Historical US survey-foot areas require a different convention.
All other units:
Square millimeter (mm²): 2589988110340
Square centimeter (cm²): 25899881103.4
Square meter (m²): 2589988.11034
Hectare (ha): 258.998811034
Square kilometer (km²): 2.58998811034
Square inch (in²): 4014489600
Square foot (ft²): 27878400
Square yard (yd²): 3097600
Acre (ac): 640

Common questions

How many square kilometers are in a square mile?: 2.589988110336 km² exactly, which this page prints as 2.58998811034 at twelve significant digits. The multiplication scales cleanly: 0.5 mi² is 1.29499405517 km², 2 mi² is 5.17997622067 km², 5 mi² is 12.9499405517 km², 10 mi² is 25.8998811034 km², 100 mi² is 258.998811034 km² and 1,000 mi² is 2,589.98811034 km².
What is the formula for square miles to square kilometers?: Use km² = mi² × 2.589988110336 with the exact international factor. In reverse use mi² = km² / 2.589988110336; multiplying by the rounded reciprocal 0.386102158542 is an approximation. One km² displays as 0.386102158542 mi², 100 km² as 38.6102158542 mi² and 500 km² as 193.051079271 mi². Swap units reverses the pair.
Why is the factor 2.59 and not 1.609344?: Area scales with the square of the length factor: an international mile is exactly 1.609344 km, and 1.609344² = 2.589988110336 exactly. The exact inverse area factor is (1 / 1.609344)² and displays as 0.386102158542 mi² per km². A length readout of 0.621371192237 mi per km is rounded; squaring that displayed decimal is a further approximation.
How many acres and square feet are in a square mile?: Exactly 640 acres and exactly 27,878,400 square feet, both of which sit in the list under the answer, along with 3,097,600 square yards, 4,014,489,600 square inches, 258.998811034 hectares and 2,589,988.11034 square metres. Those whole numbers are not rounding: the acre, the foot and the mile are defined against each other, so an acre comes back as 0.0015625 mi² with nothing left over.
Which mile is it, the international mile or the US survey mile?: This menu uses the international mile of exactly 1,609.344 m, so 1 mi² displays as 2.58998811034 km². For an explicitly supplied survey definition of 5,280 × (1200/3937) m per mile, the exact squared factor differs and is about 2.58999847032 km², roughly 10.36 m² larger per square mile. Survey mile is absent here. Confirm the source’s definition; geography or property type alone does not identify it, and the converter does not decide whether the difference meets a task’s requirements.
How big is a section or a township in square kilometers?: Those names do not establish the measured area or mile convention. If a source explicitly supplies 1 international square mile, it is exactly 640 international acres and displays as 2.58998811034 km². A supplied 36 international square miles displays as 93.2395719721 km². You can also select Acre in From for a supplied international-acre quantity. The converter does not interpret a land record or infer its boundaries.
Where do the units sit in the list under the answer?: The list shows every other unit in the area category and leaves out the one you are converting from, so here it reads square centimetre, square metre, hectare, square kilometre, square inch, square foot, square yard and acre, with the square kilometre appearing both as the headline and as a row. The readout strip carries an Uncommon units switch labelled Show 1 more, which adds the square millimetre: one square mile is 2,589,988,110,340 mm².
Why does the page open on square miles and square kilometres when I last converted something else?: This focused page opens on Square mile (mi²) to Square kilometer (km²), while preserving the main converter’s saved unit pair. When storage is usable, a saved value and uncommon-unit preference can travel between pages. Its suffix must still match From. Valid deliberate scalar edits can save those fields after a short delay; invalid or incomplete drafts preserve the saved record. Unusable or conflicting records remain until you use Forget saved settings, which keeps the current conversion on screen. Your input and converted values are calculated in the browser and are not uploaded by the converter. The definitions arrive with the page, so conversion needs no external data lookup and keeps working offline after the page has loaded. The core conversion needs no account. Copy result copies the displayed headline without digit-grouping commas; each visible conversion row has its own Copy button. Displayed and copied values round to twelve significant digits. If native copying fails, a complete selectable summary identifies the input, selected pair and conventions and includes every unit in the category, including uncommon units.

Results round to 12 significant digits using the listed unit conventions. Many factors are exact definitions; psi and parsec use rounded coefficients. Temperature includes scale offsets. Days and weeks are fixed-duration units, and unit conversion does not determine calendar dates, ambient pressure or a software label’s convention.