diff --git a/app/src/main/java/info/nightscout/androidaps/utils/TIR.kt b/app/src/main/java/info/nightscout/androidaps/utils/TIR.kt
index 9d0d662f5e..4ceb9d7504 100644
--- a/app/src/main/java/info/nightscout/androidaps/utils/TIR.kt
+++ b/app/src/main/java/info/nightscout/androidaps/utils/TIR.kt
@@ -1,5 +1,14 @@
 package info.nightscout.androidaps.utils
 
-class TIR(val low: Double, val high: Double) {
+class TIR(val date: Long, val lowThreshold: Double, val highThreshold: Double) {
+    private var below = 0;
+    private var inRange = 0;
+    private var above = 0;
+    private var error = 0;
+    private var count = 0;
 
+    fun error() = run { error++ }
+    fun below() = run { below++; count++ }
+    fun inRange() = run { inRange++; count++ }
+    fun above() = run { above++; count++ }
 }
diff --git a/app/src/main/java/info/nightscout/androidaps/utils/TirCalculator.kt b/app/src/main/java/info/nightscout/androidaps/utils/TirCalculator.kt
index ddfe9b9216..08a8c70cd7 100644
--- a/app/src/main/java/info/nightscout/androidaps/utils/TirCalculator.kt
+++ b/app/src/main/java/info/nightscout/androidaps/utils/TirCalculator.kt
@@ -1,9 +1,25 @@
 package info.nightscout.androidaps.utils
 
 import android.util.LongSparseArray
+import info.nightscout.androidaps.MainApp
 
 object TirCalculator {
-    fun calculate(days: Long): LongSparseArray<TIR> {
-        return LongSparseArray()
+    fun calculate(days: Long, lowMgdl: Double, highMgdl: Double): LongSparseArray<TIR> {
+        if (lowMgdl < 39) throw RuntimeException("Low below 39")
+        if (lowMgdl > highMgdl) throw RuntimeException("Low > High")
+        val startTime = MidnightTime.calc(DateUtil.now()) - T.days(days).msecs()
+        val endTime = MidnightTime.calc(DateUtil.now())
+
+        val bgReadings = MainApp.getDbHelper().getBgreadingsDataFromTime(startTime, endTime, true)
+        val result = LongSparseArray<TIR>()
+        for (bg in bgReadings) {
+            val midnight = MidnightTime.calc(bg.date)
+            val tir = result[midnight] ?: TIR(midnight, lowMgdl, highMgdl)
+            if (bg.value < 39) tir.error()
+            if (bg.value >= 39 && bg.value < lowMgdl) tir.below()
+            if (bg.value in lowMgdl..highMgdl) tir.inRange()
+            if (bg.value > highMgdl) tir.inRange()
+        }
+        return result
     }
 }
\ No newline at end of file