diff --git a/app/src/main/kotlin/info/appdev/chartexample/formatter/TimeRangeValueFormatter.kt b/app/src/main/kotlin/info/appdev/chartexample/formatter/TimeRangeValueFormatter.kt
new file mode 100644
index 000000000..247a4df0f
--- /dev/null
+++ b/app/src/main/kotlin/info/appdev/chartexample/formatter/TimeRangeValueFormatter.kt
@@ -0,0 +1,38 @@
+package info.appdev.chartexample.formatter
+
+import info.appdev.charting.data.BarEntryDouble
+import info.appdev.charting.data.BarEntryFloat
+import info.appdev.charting.data.EntryFloat
+import info.appdev.charting.formatter.IValueFormatter
+import info.appdev.charting.utils.ViewPortHandler
+import timber.log.Timber
+import java.text.SimpleDateFormat
+import java.util.Locale
+
+class TimeRangeValueFormatter(val format: String = "yyyy-MM-dd'T'HH:mm:ss'Z'") : IValueFormatter {
+
+    val simpleDateFormat = SimpleDateFormat(format, Locale.getDefault())
+
+    // For bar/line values
+    override fun getFormattedValue(value: Float, entryFloat: EntryFloat?, dataSetIndex: Int, viewPortHandler: ViewPortHandler?): String {
+        return when (entryFloat) {
+            is BarEntryDouble if entryFloat.yValsDouble != null -> {
+                // High-precision double path
+                val vals = entryFloat.yValsDouble!!
+                val start = vals.first().toLong()
+                val end   = vals.last().toLong()
+                "$start - $end"
+            }
+
+            is BarEntryFloat if entryFloat.yVals != null -> {
+                // Float path
+                val vals = entryFloat.yVals!!
+                val start = vals.first().toLong()
+                val end   = vals.last().toLong()
+                "$start - $end"
+            }
+
+            else -> simpleDateFormat.format(value.toLong())
+        }
+    }
+}
diff --git a/app/src/main/kotlin/info/appdev/chartexample/formatter/UnixTimeValueFormatter.kt b/app/src/main/kotlin/info/appdev/chartexample/formatter/UnixTimeValueFormatter.kt
new file mode 100644
index 000000000..dd7d48530
--- /dev/null
+++ b/app/src/main/kotlin/info/appdev/chartexample/formatter/UnixTimeValueFormatter.kt
@@ -0,0 +1,38 @@
+package info.appdev.chartexample.formatter
+
+import info.appdev.charting.data.BarEntryDouble
+import info.appdev.charting.data.BarEntryFloat
+import info.appdev.charting.data.EntryFloat
+import info.appdev.charting.formatter.IValueFormatter
+import info.appdev.charting.utils.ViewPortHandler
+import timber.log.Timber
+import java.text.SimpleDateFormat
+import java.util.Locale
+
+class UnixTimeValueFormatter(val format: String = "yyyy-MM-dd'T'HH:mm:ss'Z'") : IValueFormatter {
+
+    val simpleDateFormat = SimpleDateFormat(format, Locale.getDefault())
+
+    // For bar/line values
+    override fun getFormattedValue(value: Float, entryFloat: EntryFloat?, dataSetIndex: Int, viewPortHandler: ViewPortHandler?): String {
+        return when (entryFloat) {
+            is BarEntryDouble if entryFloat.yValsDouble != null -> {
+                // High-precision double path
+                val vals = entryFloat.yValsDouble!!
+                val start = simpleDateFormat.format(vals.first().toLong())
+                val end   = simpleDateFormat.format(vals.last().toLong())
+                "$start - $end"
+            }
+
+            is BarEntryFloat if entryFloat.yVals != null -> {
+                // Float path
+                val vals = entryFloat.yVals!!
+                val start = simpleDateFormat.format(vals.first().toLong())
+                val end   = simpleDateFormat.format(vals.last().toLong())
+                "$start - $end"
+            }
+
+            else -> simpleDateFormat.format(value.toLong())
+        }
+    }
+}