diff --git a/core/src/main/scala/filodb.core/store/ChunkSetInfo.scala b/core/src/main/scala/filodb.core/store/ChunkSetInfo.scala
index caa4a4264e..f54d1ef0e1 100644
--- a/core/src/main/scala/filodb.core/store/ChunkSetInfo.scala
+++ b/core/src/main/scala/filodb.core/store/ChunkSetInfo.scala
@@ -449,7 +449,7 @@ extends Iterator[ChunkSetInfoReader] {
     // advance window pointers and reset read index
     if (curWindowEnd == -1L) {
       curWindowEnd = start
-      curWindowStart = start - Math.max(window - 1, 0)  // window cannot be below 0, ie start should never be > end
+      curWindowStart = start - Math.max(window, 0)  // window cannot be below 0, ie start should never be > end
     } else {
       curWindowEnd += step
       curWindowStart += step
diff --git a/query/src/main/scala/filodb/query/exec/PeriodicSamplesMapper.scala b/query/src/main/scala/filodb/query/exec/PeriodicSamplesMapper.scala
index fb600d436b..7d90101bbb 100644
--- a/query/src/main/scala/filodb/query/exec/PeriodicSamplesMapper.scala
+++ b/query/src/main/scala/filodb/query/exec/PeriodicSamplesMapper.scala
@@ -343,7 +343,7 @@ class SlidingWindowIterator(raw: RangeVectorCursor,
   override def hasNext: Boolean = curWindowEnd <= end
   override def next(): TransientRow = {
     val curWindowStart = curWindowEnd - window
-    // current window is: (curWindowStart, curWindowEnd]. Excludes start, includes end.
+    // current window is: [curWindowStart, curWindowEnd]. includes start, end.
 
     // Add elements to window until end of current window has reached
     while (rows.hasNext && rows.head.timestamp <= curWindowEnd) {
@@ -377,7 +377,7 @@ class SlidingWindowIterator(raw: RangeVectorCursor,
     */
   private def shouldAddCurToWindow(curWindowStart: Long, cur: TransientRow): Boolean = {
     // cur is inside current window
-    cur.timestamp > curWindowStart
+    cur.timestamp >= curWindowStart
   }
 
   /**
@@ -389,7 +389,7 @@ class SlidingWindowIterator(raw: RangeVectorCursor,
     * @param curWindowStart start time of the current window
     */
   private def shouldRemoveWindowHead(curWindowStart: Long): Boolean = {
-    (!windowQueue.isEmpty) && windowQueue.head.timestamp <= curWindowStart
+    (!windowQueue.isEmpty) && windowQueue.head.timestamp < curWindowStart
   }
 }
 
diff --git a/query/src/main/scala/filodb/query/exec/rangefn/RateFunctions.scala b/query/src/main/scala/filodb/query/exec/rangefn/RateFunctions.scala
index 57cc2023f9..ed72c17f29 100644
--- a/query/src/main/scala/filodb/query/exec/rangefn/RateFunctions.scala
+++ b/query/src/main/scala/filodb/query/exec/rangefn/RateFunctions.scala
@@ -189,7 +189,7 @@ abstract class ChunkedRateFunctionBase extends CounterChunkedRangeFunction[Trans
     if (highestTime > lowestTime) {
       // NOTE: It seems in order to match previous code, we have to adjust the windowStart by -1 so it's "inclusive"
       val result = RateFunctions.extrapolatedRate(
-                     windowStart - 1, windowEnd, numSamples,
+                     windowStart, windowEnd, numSamples,
                      lowestTime, lowestValue,
                      highestTime, highestValue,
                      isCounter, isRate)
@@ -286,7 +286,7 @@ abstract class HistogramRateFunctionBase extends CounterChunkedRangeFunction[Tra
         val rateArray = new Array[Double](lowestValue.numBuckets)
         cforRange { 0 until rateArray.size } { b =>
           rateArray(b) = RateFunctions.extrapolatedRate(
-                           windowStart - 1, windowEnd, numSamples,
+                           windowStart, windowEnd, numSamples,
                            lowestTime, lowestValue.bucketValue(b),
                            highestTime, highestValue.bucketValue(b),
                            isCounter, isRate)
@@ -330,7 +330,7 @@ class RateOverDeltaChunkedFunctionD extends ChunkedDoubleRangeFunction {
     sumFunc.addTimeDoubleChunks(doubleVectAcc, doubleVect, doubleReader, startRowNum, endRowNum)
 
   override def apply(windowStart: Long, windowEnd: Long, sampleToEmit: TransientRow): Unit =
-    sampleToEmit.setValues(windowEnd, sumFunc.sum / (windowEnd - (windowStart - 1)) * 1000)
+    sampleToEmit.setValues(windowEnd, sumFunc.sum / (windowEnd - (windowStart)) * 1000)
   override def apply(endTimestamp: Long, sampleToEmit: TransientRow): Unit = ???
 }
 
@@ -347,7 +347,7 @@ class RateOverDeltaChunkedFunctionL extends ChunkedLongRangeFunction {
     sumFunc.addTimeChunks(longVectAcc, longVect, longReader, startRowNum, endRowNum)
 
   override def apply(windowStart: Long, windowEnd: Long, sampleToEmit: TransientRow): Unit =
-    sampleToEmit.setValues(windowEnd, sumFunc.sum / (windowEnd - (windowStart - 1)) * 1000)
+    sampleToEmit.setValues(windowEnd, sumFunc.sum / (windowEnd - (windowStart)) * 1000)
 
   override def apply(endTimestamp: Long, sampleToEmit: TransientRow): Unit = ???
 }
@@ -363,7 +363,7 @@ class RateOverDeltaChunkedFunctionH(var h: bv.MutableHistogram = bv.Histogram.em
     cforRange {
       0 until rateArray.size
     } { b =>
-      rateArray(b) = hFunc.h.bucketValue(b) / (windowEnd - (windowStart - 1)) * 1000
+      rateArray(b) = hFunc.h.bucketValue(b) / (windowEnd - windowStart) * 1000
     }
     sampleToEmit.setValues(windowEnd, bv.MutableHistogram(hFunc.h.buckets, rateArray))
   }