'Coastline Paradox'
Every coastline's measurement is based on the precision of the measurement and the scale of the map being used. More information will be displayed and measured with a longer length when the map scale is larger and the units of measurement are smaller. Therefore, there is no such thing as "an approximate response" to this topic because the resultant length increases faster than the scale of measurement.
To look at it more simply, let's imagine looking at the map of the UK from Google Maps or any map where you can zoom in on the map. The more you zoom, the more details are revealed, meaning the overall length will keep on increasing. This phenomenon is known as the name "coastline paradox". You might understand it better when looking at some of the measurements of the UK's coastline. According to the CIA Factbook, the length of the UK coastline is around 12,429 km or 7,723 miles. However, according to the World Resources Institute, this length is around 19,717 km, etc.
Moreover, the length of the coastline also changes every day when there is low tide or high tide. There is also no consensus about which features should be included in the measurement of the coastline, for example, should people also measure every headland, rock, and stone along the coastline?
