diff --git a/app/src/main/java/com/medithings/vesiscan/models/HospitalProtocol.kt b/app/src/main/java/com/medithings/vesiscan/models/HospitalProtocol.kt
index 162168f..7ce328c 100644
--- a/app/src/main/java/com/medithings/vesiscan/models/HospitalProtocol.kt
+++ b/app/src/main/java/com/medithings/vesiscan/models/HospitalProtocol.kt
@@ -160,10 +160,14 @@ object HospitalFixedParams {
  * 자세별 **프로브 기울기** 요구 범위 (2026-09-28 요청 · 사내 임상 데이터 분석 기준).
  *
  * ## 무엇을 재나
- * 기울기 = [com.medithings.vesiscan.managers.ImuPostureClassifier.classify] 의 `pitchDeg`.
- * IMU 15 샘플 평균으로 `atan(√(ax²+ay²) / |az|)` — 프로브 Z축이 중력과 벌어진 각도다.
- * 0° = 평평(누워서 배 위) · 90° = 세로. 앱이 자세 판정에 쓰는 것과 **같은 정의**라,
- * 저장된 `*_imu.csv` 의 원시값에서 분석팀이 다시 계산해도 같은 숫자가 나온다.
+ * 기울기 = [degrees]. IMU 15 샘플 평균으로 `atan2(√(ax²+ay²), az)` — 프로브 Z축이 중력과
+ * 벌어진 각도, **0°~180°**. 0° = 평평(누워서 배 위, az≈+1g) · 90° = 세로 · 180° = 뒤집힘
+ * (az≈−1g). 저장된 `*_imu.csv` 의 원시값에서 분석팀이 다시 계산해도 같은 숫자가 나온다.
+ *
+ * 2026-09-30 까지는 앱의 자세 판정([com.medithings.vesiscan.managers.ImuPostureClassifier])
+ * 과 같은 `atan(√(ax²+ay²) / |az|)` 로 0°~90° 였다 — |az| 라서 90° 를 넘으면 접혀 100° 가
+ * 80° 로 보였다. 요청으로 0°~180° 로 편다. 0°~90° 구간은 두 정의가 같으므로 Sitting
+ * 35°~55° 와 그동안의 기록은 그대로다. 자세 판정 쪽은 건드리지 않는다(낙상 감지 문턱).
  * **2026-09-28 요청자 확인: 35°~55° 는 이 정의로 낸 값이 맞다.**
  *
  * ## 왜 Sitting 만 있나
@@ -179,6 +183,21 @@ object PostureTilt {
     /** Sitting 측정 가능 기울기 (도). */
     val SITTING_DEG: ClosedFloatingPointRange<Float> = 35f..55f
 
+    /**
+     * 프로브 기울기 0°~180°. 샘플 평균의 `atan2(√(ax²+ay²), az)`. 샘플이 없으면 null —
+     * 화면은 지난 값을 유지한다(0 으로 떨어뜨리면 "평평해졌다"로 읽힌다).
+     */
+    fun degrees(samples: List<com.medithings.vesiscan.ble.ImuSample>): Float? {
+        if (samples.isEmpty()) return null
+        var ax = 0.0; var ay = 0.0; var az = 0.0
+        for (s in samples) { ax += s.ax; ay += s.ay; az += s.az }
+        val n = samples.size
+        ax /= n; ay /= n; az /= n
+        val horizontal = kotlin.math.hypot(ax, ay)
+        if (horizontal < 1e-6 && kotlin.math.abs(az) < 1e-6) return null   // 무중력·불량 샘플
+        return Math.toDegrees(kotlin.math.atan2(horizontal, az)).toFloat()
+    }
+
     fun rangeFor(posture: ClinicalPosture): ClosedFloatingPointRange<Float>? = when (posture) {
         ClinicalPosture.SITTING -> SITTING_DEG
         ClinicalPosture.SUPINE, ClinicalPosture.STANDING -> null
diff --git a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/AnchorAlignView.kt b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/AnchorAlignView.kt
index 20e8f94..1e0f1fb 100644
--- a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/AnchorAlignView.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/AnchorAlignView.kt
@@ -72,10 +72,10 @@ import com.medithings.vesiscan.managers.AnchorSelection
 import com.medithings.vesiscan.managers.AnchorStep
 import com.medithings.vesiscan.managers.ClinicalBv
 import com.medithings.vesiscan.managers.DetachWatcher
-import com.medithings.vesiscan.managers.ImuPostureClassifier
 import com.medithings.vesiscan.managers.LateralGuide
 import com.medithings.vesiscan.managers.ReattachCheck
 import com.medithings.vesiscan.models.ClinicalPosture
+import com.medithings.vesiscan.models.PostureTilt
 import com.medithings.vesiscan.models.HospitalFixedParams
 import com.medithings.vesiscan.services.HospitalRunStore
 import com.medithings.vesiscan.services.labdb.HospitalLabdbUploader
@@ -368,7 +368,7 @@ fun AnchorAlignView(appState: AppState) {
                 // IMU 는 piezo 뒤에 온다. 없으면 빈 목록 — 측정을 실패로 돌리지 않는다.
                 val imu = imuSide.await() ?: emptyList()
                 cyclesImu.add(imu)
-                if (imu.isNotEmpty()) liveTilt = ImuPostureClassifier.classify(imu).pitchDeg
+                PostureTilt.degrees(imu)?.let { liveTilt = it }
                 android.util.Log.d("AnchorAlign", "cycle $i/${AnchorConfig.ALIGN_CYCLES} imu=${imu.size}")
                 val sorted = got.sortedBy { it.channel }
                 liveChannels = sorted          // 화면 파형 — 저장·판정에 쓰는 것과 같은 데이터
@@ -515,7 +515,7 @@ fun AnchorAlignView(appState: AppState) {
                     continue
                 }
                 val imu = lrImu.await()?.takeIf { it.isNotEmpty() }
-                imu?.let { liveTilt = ImuPostureClassifier.classify(it).pitchDeg }
+                imu?.let { PostureTilt.degrees(it)?.let { t -> liveTilt = t } }
                 val sorted = got.sortedBy { it.channel }
                 liveChannels = sorted
                 detachWatcher.push(sorted.map { it.buffer })?.let { d -> detachSnapshot = d }
diff --git a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/HospitalModeView.kt b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/HospitalModeView.kt
index 61399ed..960aada 100644
--- a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/HospitalModeView.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/HospitalModeView.kt
@@ -52,7 +52,6 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import com.medithings.vesiscan.managers.AnchorBasis
 import com.medithings.vesiscan.managers.ClinicalBv
-import com.medithings.vesiscan.managers.ImuPostureClassifier
 import com.medithings.vesiscan.ui.components.ChannelDetachPanel
 import com.medithings.vesiscan.ui.components.LabdbStatusCard
 import com.medithings.vesiscan.ui.components.SixChannelWaveformGrid
@@ -345,9 +344,10 @@ fun HospitalModeView(appState: AppState) {
                         imuSide.await()?.let { imu ->
                             HospitalRunStore.appendImuSamples(file, sid, r, imu)
                             // 측정 중에도 화면의 기울기가 살아 있게 — 이 회차의 자세다.
-                            val tilt = ImuPostureClassifier.classify(imu).pitchDeg
-                            liveTilt = tilt
-                            runTilts += tilt
+                            PostureTilt.degrees(imu)?.let { tilt ->
+                                liveTilt = tilt
+                                runTilts += tilt
+                            }
                         }
                         if (saved) { ok++; okCount++ } else { fail++; failCount++ }
                         lastFile = file.name
diff --git a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/ImuTiltCard.kt b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/ImuTiltCard.kt
index dd11ba7..d1b77ac 100644
--- a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/ImuTiltCard.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/ImuTiltCard.kt
@@ -108,10 +108,10 @@ fun ImuTiltCard(
     }
 }
 
-/** 0°~90° 축 위에 요구 범위 띠와 현재 위치 눈금을 그린다. */
+/** 0°~180° 축 위에 요구 범위 띠와 현재 위치 눈금을 그린다(2026-09-30 까지는 0°~90°). */
 @Composable
 private fun TiltBand(tiltDeg: Float?, range: ClosedFloatingPointRange<Float>, accent: Color) {
-    val axisMax = 90f
+    val axisMax = 180f
     Box(
         Modifier
             .fillMaxWidth()
diff --git a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/LiveTilt.kt b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/LiveTilt.kt
index e26297a..5e167d0 100644
--- a/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/LiveTilt.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ui/views/clinical/LiveTilt.kt
@@ -12,7 +12,7 @@
 package com.medithings.vesiscan.ui.views.clinical
 
 import com.medithings.vesiscan.ble.BleManager
-import com.medithings.vesiscan.managers.ImuPostureClassifier
+import com.medithings.vesiscan.models.PostureTilt
 import kotlinx.coroutines.delay
 
 /**
@@ -35,7 +35,7 @@ suspend fun pollLiveTilt(ble: BleManager, onTilt: (Float) -> Unit) {
             side.drain()
             ble.sendImuFifoQuery()
             side.await(IDLE_TILT_POLL_MS + 300)?.let { samples ->
-                onTilt(ImuPostureClassifier.classify(samples).pitchDeg)
+                PostureTilt.degrees(samples)?.let(onTilt)
             }
             delay(IDLE_TILT_POLL_MS)
         }
diff --git a/app/src/test/java/com/medithings/vesiscan/models/PostureTiltTest.kt b/app/src/test/java/com/medithings/vesiscan/models/PostureTiltTest.kt
index 24f5999..1b8cfe1 100644
--- a/app/src/test/java/com/medithings/vesiscan/models/PostureTiltTest.kt
+++ b/app/src/test/java/com/medithings/vesiscan/models/PostureTiltTest.kt
@@ -8,6 +8,7 @@
  */
 package com.medithings.vesiscan.models
 
+import com.medithings.vesiscan.ble.ImuSample
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNull
 import org.junit.Test
@@ -27,6 +28,31 @@ class PostureTiltTest {
         assertEquals(PostureTilt.Status.ABOVE, PostureTilt.status(55.1f, ClinicalPosture.SITTING))
     }
 
+    private fun acc(ax: Float, ay: Float, az: Float) = ImuSample(ax, ay, az, 0f, 0f, 0f)
+
+    @Test
+    fun `기울기는 0에서 180 이고 90 을 넘으면 접히지 않는다`() {
+        // 2026-09-30 요청: 0~180. 옛 정의(|az|)는 100° 를 80° 로 보였다.
+        assertEquals(0f, PostureTilt.degrees(listOf(acc(0f, 0f, 1f)))!!, 0.01f)        // 평평(배 위)
+        assertEquals(90f, PostureTilt.degrees(listOf(acc(1f, 0f, 0f)))!!, 0.01f)       // 세로
+        assertEquals(90f, PostureTilt.degrees(listOf(acc(0f, 1f, 0f)))!!, 0.01f)       // 어느 축이 세로든 같다
+        assertEquals(45f, PostureTilt.degrees(listOf(acc(1f, 0f, 1f)))!!, 0.01f)
+        assertEquals(135f, PostureTilt.degrees(listOf(acc(1f, 0f, -1f)))!!, 0.01f)     // 90 넘어 기울임
+        assertEquals(180f, PostureTilt.degrees(listOf(acc(0f, 0f, -1f)))!!, 0.01f)     // 뒤집힘
+    }
+
+    @Test
+    fun `샘플 평균으로 낸다 — 한 샘플이 튀어도 15개 평균이다`() {
+        val flat = List(14) { acc(0f, 0f, 1f) } + acc(1f, 0f, 1f)
+        val d = PostureTilt.degrees(flat)!!
+        assert(d in 3f..5f) { "평균 ax=1/15 → 약 3.8° 인데 $d" }
+    }
+
+    @Test
+    fun `샘플이 없으면 null — 0 으로 떨어뜨리지 않는다`() {
+        assertNull(PostureTilt.degrees(emptyList()))
+    }
+
     @Test
     fun `다른 자세에는 범위가 없다`() {
         assertNull(PostureTilt.rangeFor(ClinicalPosture.SUPINE))