Sokuten: Survey Calculator
SIMA import & field calcs
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Read SIMA files, compute coordinates on site, and write them back — entirely on your iPhone. A coordinate calculator built for field surveying in Japan.
■ SIMA (survey data exchange format) support
Import SIMA files received via AirDrop or the Files app. After an import you see how many points, parcels, duplicate names and unreadable lines came in, and the plan draws each parcel with its area (coordinate method). Tap two points to see the distance and bearing. Unreadable lines never stop the import: a report tells you which lines were skipped and why, and unrecognized records are preserved verbatim and written back in place on export.
■ Seven field calculations
Inverse (distance, bearing, height difference), radiation, open/closed traverse with closure error and compass-rule adjustment, intersection, area (coordinate method), offset stakes, and perpendicular foot. Register any result as a new point with one tap.
■ Input built for the field
A large keypad, one-tap switching between DD.MMSS and decimal degrees, intuitive negative coordinates, and high-contrast display for outdoor readability.
■ Designed so data survives
Atomic saves with three generations of automatic backups. If a save ever fails you are told immediately and can retry. No network access; your data is never sent to our servers.
■ No subscription
All calculations, the plan and SIMA import are free. From version 1.2, points brought in from SIMA files or CSV paste do not count toward the 50 free points — points you enter by hand or register from a calculation count; SIMA and CSV imports and the bundled sample do not. Sokuten Pro (one-time purchase — see the App Store listing for current pricing) unlocks unlimited new points, SIMA/CSV export, bulk copy of all points, and unlimited history (the free version shows the last 7 days of history).
Note: Verify results before relying on them. For public survey or registration deliverables, follow the Survey Act and your client's specifications.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
From version 1.2, points brought in from SIMA files or CSV paste no longer count toward the points you can add (points added before 1.2 stay counted). After an import, a new screen shows how many points, parcels, duplicate names and unreadable lines came in, and opens the plan directly. The plan now draws SIMA parcels with their area, and tapping two points shows the distance and azimuth. Export is now a button at the top right of each site. We also fixed cases where the seconds of an angle, a distance or a coordinate showed a minus sign on zero, and where a decimal-degree azimuth showed due north as 360 degrees.
The developer, Yuya Tanaka, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Yuya Tanaka
- Size
- 3.5 MB
- Category
- Productivity
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English and Japanese
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Sokuten Pro $19.99
- Copyright
- © 2026 ZA-ONE
