Place Finder - Free Geocoding Map Tool

Place Finder: How It Works

Geocoding converts a place name or address into coordinates; reverse geocoding does the opposite. Both are approximate in ways that matter, because an address is a human construct and a coordinate is a point.

What a geocoded result actually is

Match type	Means	Accuracy
Rooftop	The building itself	Metres
Parcel centroid	The centre of the land parcel	Tens of metres
Street interpolation	Estimated position along a street from the number range	Tens to hundreds of metres
Postal code centroid	The centre of a postal area	Hundreds of metres to kilometres
City or region centroid	The centre of the administrative area	Kilometres

Interpolation is the one that surprises people. If a street runs from number 1 to 99, a geocoder may place number 50 halfway along it — which is right if numbering is even and wrong if it is not. Long rural roads and irregularly numbered streets produce results that are confidently placed and substantially off.

Always check the match type where the API reports it. A coordinate with a postal-code-centroid match is not an address.

Why addresses are hard

Formats differ by country — order, punctuation and which elements are required all vary.
Names are ambiguous. There are many places called Springfield, and several called London.
Transliteration varies. The same city has several accepted Roman spellings.
Informal addressing. In many places an address is a landmark and a description rather than a number and a street.
Places change. Streets are renamed, boundaries redrawn, and numbering revised.

Reverse geocoding

Turning coordinates into an address involves choosing which of several true answers to give. A point may sit in a building, on a parcel, in a neighbourhood, a district, a city and a region simultaneously. Which is returned depends on the requested granularity, and asking for a street address where only an area is known produces a nearby address that is not the right one.

Coordinate formats

Format	Example
Decimal degrees	13.0827, 80.2707
Degrees, minutes, seconds	13°04'58"N 80°16'15"E
Degrees and decimal minutes	13°04.96'N 80°16.24'E

Latitude always comes first in these conventions, and longitude second — but GeoJSON and several mapping libraries use the reverse order. Swapping them is among the most common bugs in mapping code, and it produces a point in the wrong hemisphere rather than a small error, which at least makes it easy to spot.

How much precision to keep

Decimal places	Resolves to about
2	1 km
3	110 m
4	11 m
5	1.1 m
6	0.11 m

Five decimal places exceeds the accuracy of most geocoding and of consumer GPS. Storing more implies a precision the data does not have — and for personal location data, storing less than you need is a reasonable privacy default.

Frequently Asked Questions

Why is the pin in the wrong place?

Most likely street interpolation — the geocoder estimated a position along the street from its number range rather than knowing the building. Long rural roads and irregularly numbered streets produce the largest errors.

How accurate is geocoding?

It depends entirely on the match type: metres for a rooftop match, tens of metres for a parcel, and potentially kilometres for a postal or city centroid. Check the match type rather than assuming the coordinate is an address.

Why do I get several results for one place name?

Because place names are not unique — there are many Springfields, and several Londons. Adding the region or country narrows it, and results are usually ranked by prominence rather than by proximity to you.

Which comes first, latitude or longitude?

Latitude first in most conventions and in everyday use — but GeoJSON and several mapping libraries use longitude first. Swapping them is a very common bug, and it places the point in the wrong hemisphere.

How many decimal places should I store?

Five gives about a metre, which already exceeds the accuracy of most geocoding and consumer GPS. Storing more implies precision the data does not have, and for personal location data less is a sensible default.

Why does reverse geocoding give a nearby address rather than mine?

Because a coordinate belongs to several regions at once and the service returns the nearest match at the requested granularity. Where only area-level data exists, it returns a nearby address rather than admitting it does not know.