How many kilometers around the Earth: distance from point to point along the equator and meridian

Have you ever wondered how many kilometers you would have to travel if you went around the world strictly along the equator? Or what distance separates two points on Earth if you fly along the shortest route - big circle? These questions seem abstract, but in practice they are critical for navigation, logistics and even planning long-distance road trips.

The earth is not a perfect sphere, but oblate ellipsoid, therefore the circumference along the equator and meridian differs by almost 68 km. This difference affects route calculations, fuel consumption and even the choice of vehicle. In this article we will look at:

• 🌍 Exact values of the length of the equator and meridians, taking into account the oblateness of the planet.
• 📏 How to calculate the distance between two points on Earth using formulas and online tools.
• 🚗 Practical examples: how much fuel is needed to travel along the equator by car.
• ✈️ Why air routes often do not coincide with straight lines on the map.

You will be surprised, but even in 2026, many navigators and mapping services use simplified models of the Earth, which can lead to errors in calculations tens of kilometers. Next is a detailed analysis with formulas, tables and useful life hacks for travelers.

1. The exact circumference of the Earth: equator vs meridian

According to data NASA and International Astronomical Union (IAU), The Earth has the following parameters:

• 🔵 Equatorial radius: 6,378.137 km (maximum, due to the convexity at the equator).
• 🔴 Polar radius: 6,356.752 km (minimum, at the poles).
• 🟢 Average radius: 6,371.0088 km (used in most calculations).

Because of this difference, the circumference of the equator and the meridian are not the same:

These data are confirmed by satellite measurements, including missions GRACE (NASA/DLR) and GOCE (ESA). I wonder what Mount Chimborazo in Ecuador (6,263 m above sea level) is technically the farthest point from the center of the Earth - its top is at 2.1 km further than the summit of Everest due to the equatorial bulge.

⚠️ Attention: Many school textbooks and old maps use a rounded value for the length of the equator - 40,075 km. However, for accurate calculations (for example, in aviation), it is important to take into account the oblateness of the planet, otherwise the error can reach 0,02%, which at a distance of 10,000 km gives an error of 2 km.

2. How to calculate the distance between two points on Earth

To calculate the shortest distance between two points on a sphere (or ellipsoid), use the formula Haversines (haversine formula). It takes into account the latitude and longitude of points and the curvature of the Earth:

a = sin²(Δlat/2) + cos(lat1)  cos(lat2)  sin²(Δlon/2)
c = 2 * atan2(√a, √(1−a))
d = R * c

Where:

• 📍 lat1, lon1 — latitude and longitude of the first point.
• 📍 lat2, lon2 — latitude and longitude of the second point.
• 🌐 R — radius of the Earth (6,371 km for simplified calculations).
• 📏 d — distance in kilometers.

In practice, this formula is implemented in Google Maps API, OpenStreetMap and specialized navigators for cargo transportation (for example, Sygic Truck). For quick calculations you can use online calculators:

• 🌐 Movable Type Scripts (exact calculation taking into account the WGS84 ellipsoid).
• 🚛 FreeMapTools (allows you to build a route in a large circle).

3. Why do air routes not line up with straight lines on the map?

On a flat map (such as the Mercator projection), the shortest path between two points looks like a curved line. This is due to the fact that:

1. Big circle (orthodromy) is the shortest path on a sphere, but on the map it is depicted as an arc.
2. Loxodrome - line of constant exchange rate (for example, 30° northeast), but it is longer than the orthodrome.

Examples:

• ✈️ Flight Moscow — Los Angeles runs over Alaska, and not across the Atlantic, as it might seem on the map.
• 🚢 Marine vessels often choose rhoxodrome to simplify navigation, despite the longer distance.

⚠️ Attention: When planning road trips across Russia (for example, from Moscow to Khabarovsk), the difference between the “straight” line on the map and the real route can reach 1,000+ km due to terrain, borders and road infrastructure. Always check the route in Yandex.Navigator or Waze depending on the type of vehicle.

4. Practical examples: how much fuel is needed to travel along the equator

Let's say you decide to drive along the equator in a car with average fuel consumption 8 l/100 km. Let's calculate the costs:

1. Equator length: 40,075 km.
2. Fuel consumption: 40,075 km × 8 l / 100 km = 3,206 l.
3. Cost (at a price 50 rub/l): 3,206 × 50 = 160,300 rubles.

But this theoretical calculation. In practice, you need to consider:

Irregular refueling in remote regions|Tire wear (the equator passes through 14 countries with different road surfaces)|Visas and border fees (for example, crossing through Congo or Indonesia)|Fuel reserve in case of force majeure (recommended +20%)

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For comparison: traveling around the world by motorcycle along the equator took the traveler Nick Sanderson 19 months (2017–2019). He overcame 38,000 km (not exactly along the equator due to political and geographical restrictions) and spent approx. 5,000 liters of gasoline.

5. How the Earth was measured in ancient times: from Eratosthenes to GPS

The first person to accurately measure the circumference of the Earth was Eratosthenes of Cyrene (~240 BC). His method:

1. Measured the length of the shadow in Alexandria and Siena (now Aswan) at noon of the summer solstice.
2. The angle of incidence of the sun's rays differed on 7,2° (1/50 of a full circle).
3. Distance between cities — 800 km (according to measurements, the bema is the Egyptian measure of length).
4. Circumference of the Earth: 800 km × 50 = 40,000 km (all error 0,2%!).

Modern methods:

• 🛰️ Satellite geodesy (GPS, GLONASS): accuracy up to 1 cm.
• 📡 Laser ranging (for example, mission LAGEOS): measures the displacement of continents.
• 🌊 Acoustic sensing: Used for mapping the seabed.

6. Online services for calculating distances between points

For accurate calculations, use the following tools:

For road travelers we recommend:

• 🚗 Waze — takes into account traffic jams and road events.
• 🚛 TruckMap — a specialized navigator for trucks with height/weight restrictions.
• 🏍️ Kurviger — optimizes routes for motorcyclists (avoids gravel, bad roads).

7. Common mistakes when calculating distances on Earth

Even experienced travelers make these mistakes:

1. Ignoring the oblateness of the Earth: use average radius (6,371 km) instead of the ellipsoidal model (WGS84) can give an error of up to 0,5% over long distances.
2. Confusion between sea and land miles:
   • 🌊 nautical mile = 1,852 m (based on the length of the 1' meridian arc).
   • 🚗 Land mile = 1,609 m (used in US/UK).

⚠️ Attention: When planning sea voyages, never use land miles for fuel calculations! Error in 10% at a distance of 5,000 km will lead to a shortage 500+ liters of diesel for a yacht.

FAQ: Answers to popular questions

40,075 km / 100 km/h = 400.75 hours ≈ 16.7 days.