Sessagesimale – Calculator 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

Free, 15 calculations a day · full version for €2.99, one time · 7 languages

  • Free, no subscription
  • 100% offline
  • No account
  • No data collection
  • 7 languages
Sessagesimale on iPhone: an angle in degrees, minutes and seconds with the decimal display

Free, with an optional unlock

Download the app for free and use it every day. If you need more, a single purchase, with no subscription, unlocks the full version.

Free

  • 15 calculations a day, in every mode
  • DMS and DDM angles, time and decimal
  • Conversions panel, memory and history

Full version

  • Unlimited calculations
  • Compass (iPhone)
  • Apple Watch app
  • Shortcuts actions

One-time purchase of €2.99 (the price may vary by country), no subscription. If you already bought the paid app, everything is unlocked with nothing to do. With Family Sharing, up to five family members use the unlock for a single purchase.

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
Calculator showing the counter of free calculations left today
Free every day
Full version screen shown when the daily limit is reached, with one-time purchase and restore
Full version

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

Yes, it is a free download and allows 15 calculations a day in every mode. A one-time purchase, “Full version” (€2.99, the price may vary by country), with no subscription, unlocks unlimited calculations, the compass, the Apple Watch app and Shortcuts actions. The free-calculation counter resets at midnight.

No. If you bought the app before it became free, everything is already unlocked, with nothing to do and nothing to pay again.

Yes. With Family Sharing, up to five family members use the unlock for a single purchase.

Download Sessagesimale again from the Purchased section of your Apple ID on the App Store, then tap Restore Purchases on the Full version screen: the unlock comes back at no extra cost. If you bought the paid app, everything is already unlocked. History and memory live on the device, so they come back only if you restore a full backup.

Payments and refunds are handled by Apple: you can make a request at reportaproblem.apple.com.

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.

Type the degrees, then tap the contextual key ▸ ′ to move to minutes and ▸ ″ for seconds. The active field is highlighted. On seconds (or on minutes in DDM) the same key becomes your language’s decimal separator.

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: you can switch sub-format in Angle mode and the value converts by itself.

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. Tap a row to copy it.

It works completely offline. There is no account and no data collection: history and memory stay on your device only (in the history, swipe an entry to delete it). The only connection is to the App Store, for the full version purchase. 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. If a value is not recognized, try removing the text around it.

Yes: digits, operators, Return for the result and Esc to clear everything.

iPhone and iPad only (not available for Mac or Apple Vision), with the Apple Watch app included in the full version. The interface is available in Italian, English, German, Spanish, French, Japanese and Korean. It is free 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.

Download on theApp Store

Also available in: Italiano