Free Radius Area Map & Coverage Calculator
Click any point on the map and enter a radius to visualize a circular coverage zone and calculate the exact area in square kilometres, square miles, acres, and hectares.
Enter a radius, choose kilometres or miles, then click the map to place the circle centre and calculate the covered area.
Click the map to place the circle centre.
Quick answer
To find the area covered by a circle on a map, enter a radius in kilometres or miles, then click the centre point on the map. The tool draws the circle and calculates area using A = πr², where r is the radius on Earth's surface. A 10 km radius covers π × 100 ≈ 314.2 km². A 50 km radius covers π × 2,500 ≈ 7,854 km². This is useful for delivery zones, cell-tower coverage, emergency evacuation areas, and property-search radii.
Formula & method
A = π · r²
- A — Area of the circle (km² or mi²)
- π — Pi, approximately 3.14159
- r — Radius (km or miles)
Area of a circle. For map use, r is the radius in km or miles, giving area in km² or mi².
Examples
- Input
- r = 10 km
- Result
- A = 314.16 km²
- Why
- A = π × 10² = π × 100 = 314.159 km². This is a typical last-mile delivery radius for an urban warehouse.
- Input
- r = 5 miles
- Result
- A ≈ 78.54 mi² (203.4 km²)
- Why
- A = π × 5² = π × 25 ≈ 78.54 mi². Converting: 78.54 × 2.58999 ≈ 203.4 km². A school catchment or cell-tower coverage zone often uses a similar radius.
- Input
- r = 50 km
- Result
- A = 7,853.98 km²
- Why
- A = π × 50² = π × 2,500 = 7,853.98 km². This is comparable to the area of an entire county or prefecture.
- Input
- r = 1 km
- Result
- A ≈ 3.14 km² (314 ha)
- Why
- A = π × 1² = 3.14159 km². Converting to hectares: 3.14159 × 100 = 314.16 ha. Useful for local property or amenity searches.
When to use this tool
- Planning delivery or service zones centred on a warehouse or store.
- Analysing cell-tower, Wi-Fi, or emergency broadcast coverage areas.
- Setting a property search radius around a workplace or school.
- Evacuation planning — visualising how far a circular exclusion or safe-zone extends.
Common mistakes
- Squaring the diameter instead of the radius — always use r (half the width), not the full diameter.
- Forgetting to convert units — if you enter radius in km, the area result is in km², not m² or hectares.
- Assuming a flat-map circle equals the same area on Earth's surface — for radii above ~500 km, Earth's curvature causes the flat-circle area to over-estimate the true spherical cap area.
- Confusing hectares and km²: 1 km² = 100 hectares; 1 hectare = 10,000 m².
Frequently asked questions
How do I convert km² to hectares?
1 km² = 100 hectares. Multiply the km² value by 100. For example, 314 km² = 31,400 hectares.
How do I convert km² to square miles?
1 km² = 0.3861 mi². Multiply the km² value by 0.3861. For example, 314 km² ≈ 121.2 mi².
Is the circle on the map accurate near the poles?
For small to medium radii (under ~500 km) the difference is negligible in practice. Very large circles near the poles will appear distorted on a Mercator-projected map but the area formula remains correct.
Can I use miles instead of kilometres?
Yes — toggle the unit selector to miles. The map circle and all area outputs update automatically. 1 mile = 1.60934 km.
What is 1 acre in km²?
1 acre = 0.00404686 km². To convert km² to acres, multiply by 247.105.
Does the map show actual cities or landmarks within the circle?
Yes — the underlying OpenStreetMap tiles show roads, cities, and landmarks. This makes it easy to visually assess what falls within your coverage zone.
Sources & references
External references open in a new tab. We are independent and not affiliated with these organizations.
- ✓ Free to use
- ✓ No sign-up required
- ✓ Runs entirely in your browser — nothing is uploaded.
- ✓ Formula and method shown above
Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.
Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.
Related tools
- GPS Coordinate FinderGeography & Maps
- Map Distance CalculatorGeography & Maps
- Haversine Distance CalculatorDeveloper
- Pythagorean Theorem CalculatorCalculators
Embed this tool on your site
Free to embed, no sign-up. Paste this code where you want the radius area map to appear: