Accident Investigation Calculator

OS Grid to Latitude and Longitude

Please read the following instructions carefully.

The calculator accepts full‑precision Ordnance Survey (OS) grid references in either of the following formats:

• Lettered form: 2 letters + 5‑digit easting + 5‑digit northing
  Example: SZ 65750 98047
• Numeric form: 6‑digit easting + 6‑digit northing
  Example: 465750 598047

If your reference is shorter (4‑, 6‑ or 8‑figure), pad zeros on the right‑hand end of each numeric part until you reach 5 digits (lettered form) or 6 digits (numeric form).

For Example:

• NZ 576 060 → NZ 57600 06000
• 123 456 → 123000 456000

In the boxes below, either enter the 6 digit + 6 digit Eastings and Northings (e.g. 450737 and 533255), OR the two letter + 5 digit + 5 digit OS Grid Reference (e.g. NZ 57600 06000). Then click on the Calculate button to convert them.

If the resulting Longitude is negative, it is West (e.g. -1.234 would be 1.234 W).

Eastings

Northings

OS Grid Reference

Calculate

Latitude: ° ′ ″
Decimal: °

Longitude: ° ′ ″
Decimal: °

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References

The algorithm used in this calculator is described at: National GPS Reference Information

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