Sunlight Checker: Sun & Shadow

NEW: Tap a building to see its height, storeys, zoning, coverage and floor-area ratios, and flood risk — alongside real sunlight hours. Check homes before you visit.

Will your next home actually get sunlight? "South-facing" on the listing doesn't tell you what the buildings around it do to the sun.

Sunlight Checker computes real sunlight hours for any address in Japan's major cities. Tap the map and it simulates the sun's path for all 12 months, using the Japanese government's official PLATEAU 3D city model to account for shadows cast by every surrounding building.

FREE FEATURES

• Sunlight hours per month and yearly average, scored S to D
• Floor selector — see how sunlight changes from the 1st to the top floor
• Building details: height, storeys, zoning, building-coverage ratio, floor-area ratio, flood and landslide risk (PLATEAU attributes, availability varies by city)
• Save up to 1,000 favorite locations

PRO FEATURES

• Hourly timeline in 15-minute steps
• 3D shadow visualization
• Direction filter (south-facing windows only, etc.)

COVERAGE Tokyo 23 wards, Yokohama, Kawasaki, Osaka, Nagoya, Fukuoka, Sapporo, Saitama and other major cities.

PRIVACY All computation happens on your device. Searched addresses are never sent to a server.

Note: The app interface is currently Japanese only. The map and numeric results are easy to follow, and this page's screenshots show exactly what you'll see.

Privacy policy: https://sunlightchecker.remosia.biz/privacy.html Terms: https://sunlightchecker.remosia.biz/terms.html

Building data: Ministry of Land, Infrastructure, Transport and Tourism (MLIT) PLATEAU, adapted (https://www.mlit.go.jp/plateau/)