How Many Decimal Places Do You Need for Precise Latitude and Longitude Storage?

Precision Considerations in Storing Latitude and Longitude

When dealing with latitude and longitude, determining the appropriate level of accuracy for storage is crucial. The general recommendation is to use Decimal(9,6), but the actual precision required will vary depending on the intended application.

To determine the number of decimal points needed for a desired accuracy, consider the following:

Impact of Decimal Points on Accuracy

Each decimal point in latitude or longitude provides a specific level of accuracy. The following table illustrates the relationship between decimal places and accuracy at the equator:

Decimal Places	Degrees	Distance
0	1.0	111 km
1	0.1	11.1 km
2	0.01	1.11 km
3	0.001	111 m
4	0.0001	11.1 m
5	0.00001	1.11 m
6	0.000001	0.111 m
7	0.0000001	1.11 cm

Determining Precision for 50 Feet Accuracy

To store a location within 50 feet of its exact coordinate, you would need at least 5 decimal places. This corresponds to an accuracy of approximately 1.11 meters at the equator.

Non-Programming Perspective: Accuracy per Decimal Point

For a non-programming perspective, the accuracy per decimal point is as follows:

• 1 decimal point: Approximately 11.1 km
• 2 decimal points: Approximately 1.11 km
• 3 decimal points: Approximately 111 m
• 4 decimal points: Approximately 11.1 m
• 5 decimal points: Approximately 1.11 m
• 6 decimal points: Approximately 0.111 m

In conclusion, the appropriate level of accuracy for storing latitude and longitude depends on the specific application. For general purposes, using Decimal(9,6) provides a good balance between accuracy and storage efficiency. However, if extreme precision is required, you may need to consider a different data type or approach.

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