diff --git a/app/engine/utils/WeighedSeries.js b/app/engine/utils/WeighedSeries.js
new file mode 100644
index 0000000..8a7183d
--- /dev/null
+++ b/app/engine/utils/WeighedSeries.js
@@ -0,0 +1,103 @@
+'use strict'
+/*
+  Open Rowing Monitor, https://github.com/laberning/openrowingmonitor
+
+  This creates a series with weights
+  It allows for determining the Average, Weighed Average, Median, Number of Positive, number of Negative
+*/
+
+import { createSeries } from './Series.js'
+
+function createWeighedSeries (maxSeriesLength) {
+  const dataArray = createSeries(maxSeriesLength)
+  const weightArray = createSeries(maxSeriesLength)
+  const weightedArray = createSeries(maxSeriesLength)
+
+  function push (value, weight) {
+    dataArray.push(value)
+    weightArray.push(weight)
+    weightedArray.push(value * weight)
+  }
+
+  function length () {
+    return dataArray.length()
+  }
+
+  function atSeriesBegin () {
+    return dataArray.atSeriesBegin()
+  }
+
+  function atSeriesEnd () {
+    return dataArray.atSeriesEnd()
+  }
+
+  function get (position) {
+    return dataArray.get(position)
+  }
+
+  function numberOfValuesAbove (testedValue) {
+    return dataArray.numberOfValuesAbove(testedValue)
+  }
+
+  function numberOfValuesEqualOrBelow (testedValue) {
+    return dataArray.numberOfValuesEqualOrBelow(testedValue)
+  }
+
+  function sum () {
+    return dataArray.sum()
+  }
+
+  function average () {
+    return dataArray.average()
+  }
+
+  function weighedAverage () {
+    if (dataArray.length() > 0 && weightArray.sum() !== 0) {
+      return (weightedArray.sum() / weightArray.sum())
+    } else {
+      return undefined
+    }
+  }
+
+  function minimum () {
+    return dataArray.minimum()
+  }
+
+  function maximum () {
+    return dataArray.maximum()
+  }
+
+  function median () {
+    return dataArray.median()
+  }
+
+  function series () {
+    return dataArray.series()
+  }
+
+  function reset () {
+    dataArray.reset()
+    weightArray.reset()
+    weightedArray.reset()
+  }
+
+  return {
+    push,
+    length,
+    atSeriesBegin,
+    atSeriesEnd,
+    get,
+    numberOfValuesAbove,
+    numberOfValuesEqualOrBelow,
+    sum,
+    average,
+    weighedAverage,
+    minimum,
+    maximum,
+    median,
+    series,
+    reset
+  }
+}
+
+export { createWeighedSeries }