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Oahu is the third largest and most populous of the Hawaiian Islands. If you’re wondering about the actual size of Oahu, here’s a quick answer: Oahu covers 597.1 square miles of land area.

In this comprehensive guide, we will explore various aspects related to the size of Oahu, including its land area, population size, and major geographic regions. We’ll compare Oahu to other Hawaiian islands and dig deep into specifics on the island’s different districts and landmarks.

Read on to learn all about how truly big this iconic Pacific island is!

Land Area and Dimensions of Oahu

Total Land Area

The total land area of the island of Oahu is approximately 598 square miles (1,545 square kilometers). This makes Oahu the third largest island in the Hawaiian island chain, behind the Big Island of Hawaii and Maui.

Oahu accounts for just 4% of the total land area of the state of Hawaii. However, Oahu is home to the state’s capital and largest city, Honolulu, and nearly 1 million residents, making it the most populous Hawaiian island.

Length and Width Dimensions

Oahu stretches approximately 44 miles (71 kilometers) from east to west and 30 miles (48 kilometers) from north to south at its widest points. So the island has an elongated shape oriented in a southwest to northeast direction.

The longest straight-line distance on Oahu is the length from Kaena Point on the western tip to Makapuu Point on the eastern tip, spanning 44 miles. The widest straight-line transect is the approximately 30 mile distance from Kaena Point to the northern shore in Kahuku.

How Oahu Ranks in Size Among the Hawaiian Islands

Of the 8 main Hawaiian islands, Oahu ranks:

  • 3rd in total land area behind the Island of Hawaii (the “Big Island”) at 4,028 square miles and Maui at 727 square miles
  • 3rd in coastline length at 112 miles, compared to the Big Island (266 miles) and Kauai (162 miles)
  • 5th in maximum elevation at the summit of Mount Kaala at 4,025 feet, lower than peaks on the Big Island, Maui, Molokai, and Kauai

So while Oahu does not stand out in terms of raw size or elevation, its relatively large population and economic impact make it hugely important for Hawaii and the United States. The island’s nicknames of “The Gathering Place” and “The Heart of Hawaii” reflect its central role in culture and finance in the Hawaiian Islands.

Hawaiian Island Land Area (sq mi) Max Elevation (ft)
Hawaii 4,028 13,796
Maui 727 10,023
Oahu 598 4,025

Population Size and Density

Resident Population

As of 2021, Oahu had an estimated resident population of over 1 million people, making it by far the most populated island in Hawaii. The island contains Honolulu, which is Hawaii’s capital and largest city with over 350,000 residents alone.

Oahu’s population has grown steadily over the past several decades, with an increase of 5.6% from 2010 to 2020. This influx can be attributed to economic and job opportunities, as well as Oahu’s stunning natural landscapes that draw new residents every year.

Population Density

With a total land area of just 597 square miles, Oahu has a high overall population density of around 1,636 people per square mile. However, population distribution is extremely uneven, with highly urbanized areas contrasting sparsely populated regions.

Region Population Density (people per sq. mile)
Urban Honolulu 5,664
Wahiawa 2,784
Kaneohe 2,708
Koolaupoko 1,298
Waianae 2,306
Koolauloa 529
Ewa 3,095
Central Oahu 2,111

As illustrated, the urban core of Honolulu and nearby regions like Ewa and Wahiawa are extremely densely settled. More suburban communities like Kaneohe and Koolaupoko have moderately high density. Meanwhile, the northern Koolauloa district is far more sparsely populated.

Population Distribution by Region

As of 2019 estimates, here is how Oahu’s total population of just over 1 million is distributed geographically:

  • Primary Urban Center (Honolulu metro): approximately 72%
  • Ewa: 11.7%
  • Central Oahu: 6.3%
  • Koolaupoko: 3.9%
  • Waianae: 3.7%
  • Koolauloa: 2.5%

Clearly the dense capital city of Honolulu dominates demographically, containing nearly 3/4 of the island’s entire population. Areas west and central to Honolulu like Ewa and Central Oahu compose smaller but still significant population cores.

In contrast, more distant and mountainous communities such as Koolauloa are far less populated.

Breakdown of Regions and Districts

Main Geographic Regions

The island of Oahu can broadly be divided into three main geographic regions: the mountainous Koʻolau Range in the east, the Waiʻanae Range in the west, and the populated coastal plains in between. The volcanic Koʻolau mountains cover a large portion of windward (northeastern) Oahu, with steep ridges, narrow valleys, and numerous streams and waterfalls.

The Waiʻanae mountains on the leeward (southwestern) side are older and more weathered but still scenic. Between these two mountain ranges lies the most populous region – the southern coastal plain.

This coastal plain is home to famous beaches like Waikiki, urban Honolulu, sprawling suburbs, and resort areas. It has a population density of over 4,500 residents per square mile – one of the highest of any US city (Reference: Best Places).

The northern shores, meanwhile, have stunning sandy beaches, offshore reefs, and fewer crowds. Central Oahu has a mix of suburban development, pineapple plantations, and former sugarcane fields.

Land Area of Key Districts and Towns

Honolulu County covers the entire island of Oahu. Within it lies the City and County of Honolulu, which governs just under 70% of the island’s total land area. The island itself covers about 600 square miles in area (Reference: Hawaii Guide).

District Land Area (sq. miles)
Urban Honolulu 85
ʻEwa District (suburban area) 70
Koolauloa District (windward/north shore) approx. 100
Waianae District (leeward/west side) 85
Central Oahu District 130

Some key towns outside the main Honolulu urban area include:

  • Kailua – 12 sq. miles on the windward side, known for beaches and outdoor recreation
  • Kāneʻohe – 12 sq. miles, a residential community on the windward side
  • Mililani – 12 sq. miles, a master-planned suburban community in central Oahu
  • Wahiawa – 4 sq. miles, an agricultural town in central Oahu

As you can see, Oahu offers tremendous geographic diversity across its regions and districts. Whether you seek world-famous beaches, remote hiking trails, suburban living, or an urban jungle, you’re sure to find your niche somewhere on the island!

Notable Landmarks and Natural Features

Prominent Mountains

The Koʻolau Range makes up the eastern half of Oahu, with majestic peaks like Mount Kaʻala, the highest point on the island at 4,020 feet. The Waiʻanae Range defines the western coastline, featuring the famous Leahi (Diamond Head) crater rising 760 feet above sea level.

An extinct volcano, Diamond Head offers stunning 360-degree views from its summit after a steep 0.8 mile hike. The iconic silhouette serves as an iconic Oahu landmark. Other peaks in the Waiʻanae Range include Mount Kaʻala and the ridge-like Kolekole Pass.

Famous Beaches

With so much coastline, Oahu boasts world-famous beaches for every taste. On the North Shore, the Banzai Pipeline draws expert surfers tackling 15- to 25-foot waves, while Ehukai Beach Park offers incredible views.

Iconic Waikiki Beach hosts millions of visitors every year to lounge on its sunny two miles of white sand. For snorkeling, Hanauma Bay Nature Preserve’s curved bay shelters diverse marine life. Sandy Beach Park and Makapuu Beach Park offer bodyboarding and surfing waves.

And the remote Kaena Point features a scenic nature reserve great for spotting whales.

Other Geographic Highlights

Visitors also flock to see striking geographic features like the Halona Blowhole, which shoots sea water 30+ feet in the air when waves hit it just right. Along the eastern coastline, the scenic Nuʻuanu Pali Lookout overlooks the sheer Koolau cliffs – the area where King Kamehameha I conquered Oahu in 1795.

Colorful coral reefs ring sections of the island. Molokai Channel and Kaiwi Channel to the south offer particularly good sites for snorkeling, diving, or glass-bottom boat tours of the coral lined with bright tropical fish.

And hidden waterfalls like Manoa Falls reward hikers with refreshing plunge pools amid lush foliage.

With mountain ranges making up over 65% of the island, Oahu contains incredibly varied terrain blanketed in vibrant plant life. Exploring these landmarks and natural features lets visitors experience the diverse beauty of Hawaii’s “Gathering Place.” Statistics from the Department of Business, Economic Development & Tourism ( show over 5.87 million visitors came to Oahu in 2018 to take in famous sights like Waikiki, Diamond Head, and the North Shore beaches.


As we’ve explored, Oahu covers nearly 600 square miles of diverse landscapes, from sandy beaches to volcanic peaks. With around one million residents, it’s a vibrant island that offers city amenities alongside natural beauty.

We broke down specifics on the different regions, landmarks, and populated areas that make up Oahu. While secondary to some of Hawaii’s larger islands in total size, Oahu still packs in a wide array of environments and destinations into its compact area.

Hopefully this guide gave you a comprehensive picture of just how big this iconic Pacific island is!

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