App for iPhone and iPad

Sessagesimale, the sexagesimal calculator for degrees, minutes, seconds and time

Add, subtract and convert DMS/DDM angles, time and GPS coordinates without going through decimals. For surveying, navigation and astronomy. 100% offline.

Download on theApp Store

Just €2.99 · 7 languages · no account

100% offline
No account
No data collection
7 languages

Sessagesimale on iPhone: an angle in degrees, minutes and seconds with the decimal display

Built for people who work in base 60

Enter values exactly as you read them on a map, a measuring instrument or a stopwatch: the result comes back normalized, with carries done (45′ + 30′ = 1° 15′).

Field-by-field entry

A contextual key moves you from degrees to minutes to seconds (▸ ′, ▸ ″), and on seconds it becomes your language’s decimal separator. The active field is always highlighted.

Dual display

As you type in sexagesimal you read the decimal equivalent in real time, and vice versa. No more mental math between 40° 42′ 46″ and 40.71278°.

Conversions panel

One tap shows the value as DMS, DDM, time, decimal degrees, radians, gon, NATO mils, slope and hours↔degrees (×15). Tap any row to copy it.

DMS and DDM angles, time, decimal

Three modes in one app. DDM (degrees and decimal minutes) is the format of many GPS receivers and of maritime and aeronautical navigation.

Memory and history

MC, MR, M+, M−, plus a persistent history: tap an entry to reuse its result, swipe to delete it, share everything as text. On iPad the history sits alongside.

Hardware keyboard

On iPad, use your keyboard: digits, operators, Return for the result, Esc to clear.

Full VoiceOver support

Contextual labels on every key and value, so the app is usable without looking at the screen.

Light and dark theme

Adaptive layouts for iPhone in portrait and landscape and for iPad, with a dark mode and three alternative icons.

A look at the app

Angle calculator in degrees, minutes and seconds (DMS) with decimal display — DMS angle

Conversions panel: radians, gon, NATO mils, slope and hours to degrees — Conversions

Hours, minutes and seconds calculation in time mode — Time

Calculation history with one-tap reuse of results — History

Sexagesimal calculator in dark theme — Dark theme

From degrees to gon, from NATO mils to slope

The conversions panel shows every representation of the current value at once. Handy when the survey is in gon, the binoculars in NATO mils and the map in degrees.

DMS and DDMdegrees, minutes and seconds, or degrees and decimal minutes (40° 42′ 46″ = 40° 42.7667′)
Decimal degrees and radiansfor formulas, spreadsheets and code
Gon (gradians)400 gon = a full turn, used in surveying and geodesy
NATO mils6400 mils = a full turn, used in military applications and aiming
Slopethe angle expressed as a percentage
Quadrant bearingdirection expressed by quadrant, such as N 45° E
Hours ↔ degrees (×15)for right ascension and time zones

Sessagesimale conversions panel: DMS, DDM, time, radians, gon, NATO mils and slope

On iPad the history sits next to your calculation

With more room, the calculator and the history stay visible together: reuse a previous result with one tap, without switching screens. With a hardware keyboard you work even faster.

Sessagesimale on iPad with the calculation history shown beside the calculator

Who it’s for

Surveying and geodesy

Surveyors and engineers adding up survey angles and converting to gon.

Navigation

Sailors and pilots working with GPS coordinates in degrees and decimal minutes, and with bearings.

Astronomy

Amateur and professional astronomers: right ascension in hours, declination in degrees, ×15 conversions.

Study

Trigonometry and geodesy students who want to check their work without mental conversions.

Frequently asked questions

A value expressed in base 60, like degrees (1° = 60 minutes of arc, 1 minute = 60 seconds) and time (1 hour = 60 minutes, 1 minute = 60 seconds). Sessagesimale adds, subtracts, multiplies and divides by a scalar directly in this format, with automatic carrying.

DMS is degrees, minutes and seconds (e.g. 40° 42′ 46″). DDM is degrees and decimal minutes (e.g. 40° 42.7667′), the format of many GPS receivers and of maritime and aeronautical navigation. The app handles both and converts between them.

The gon (or gradian) divides a full turn into 400 parts, so 90° = 100 gon. The NATO mil divides it into 6400 parts. The conversions panel shows both, along with radians and slope as a percentage.

It works completely offline. There is no account, no data collection and no connection to external servers: history and memory stay on your device only. Details in the privacy policy.

Yes. The app recognizes decimals with a period or comma, sexagesimal values with ° ′ ″ (including typographic symbols) and the 12:34:56 notation. You can also copy the current value and share it through the system sheet.

iPhone and iPad only (not available for Mac or Apple Vision). The interface is available in Italian, English, German, Spanish, French, Japanese and Korean. It costs €2.99 on the App Store. For help, see the Support page.

Stop converting in your head

Degrees, minutes and seconds, time and coordinates in one calculator, always with you and without a connection.