Nautical angle calculator

This calculator is used to add and subtract angles in the form used in the Nautical Almanac, a publication with data used for navigation by ships. The angles in this publication are expressed in degrees in the usual way (0° to 359°), each degree is divided into 60 minutes, but each minute is divided into ten decimals (and not into 60 seconds).

  • Thus: 34° 59.9' is read as 34 degrees 59.9 minutes.
  • and: 34° 59.9' + 0.1' = 35° 00.0'
° '


The calculator adds or subtracts input values from the running total in the top window.

  • Enter a value in two parts: the degrees in one field and minutes in the other.
  • Press Enter. The input value will be entered into the running total, replacing whatever was there. Or:
  • Press either the Plus or Minus button to add/subtract the input from the running total.


The decimal part of the minutes output is rounded to 1 decimal place to be consistent with navigation practice. However, the internal result is kept to the highest possible precision so that successive operations do not produce a cumulative error.

Automatic conversion to Degrees - Minutes - Seconds

Whenever the calculator outputs a new result it also displays it in the Degrees - Minutes - Seconds format just below the main display window.

See also Degrees - Minutes - Seconds angle calculator.
While you are here..

... I have a small favor to ask. Over the years we have used advertising to support the site so it can remain free for everyone. However, advertising revenue is falling and I have always hated the ads. So, would you go to Patreon and become a patron of the site? When we reach the goal I will remove all advertising from the site.

It only takes a minute and any amount would be greatly appreciated. Thank you for considering it!   – John Page

Become a patron of the site at

Other angle topics


Angle Types

Angle relationships