Sokuten: Survey Calculator

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. 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 and SIMA import (up to 50 points) are free to try. Sokuten Pro (one-time purchase — see the App Store listing for current pricing) unlocks unlimited points, SIMA/CSV export, and unlimited history.

Note: Verify results before relying on them. For public survey or registration deliverables, follow the Survey Act and your client's specifications.