diff --git a/src/ripple/basics/RangeSet.h b/src/ripple/basics/RangeSet.h
index 903e6a1e4..c66a945fe 100644
--- a/src/ripple/basics/RangeSet.h
+++ b/src/ripple/basics/RangeSet.h
@@ -57,6 +57,10 @@ public:
 
     std::string toString () const;
 
+    /** Returns the sum of the Lebesgue measures of all sub-ranges. */
+    std::size_t
+    lebesgue_sum() const;
+
     /** Check invariants of the data.
 
         This is for diagnostics, and does nothing in release builds.
diff --git a/src/ripple/basics/impl/RangeSet.cpp b/src/ripple/basics/impl/RangeSet.cpp
index 362545c0e..0bfc627fd 100644
--- a/src/ripple/basics/impl/RangeSet.cpp
+++ b/src/ripple/basics/impl/RangeSet.cpp
@@ -235,6 +235,15 @@ void RangeSet::simplify ()
     }
 }
 
+std::size_t
+RangeSet::lebesgue_sum() const
+{
+    std::size_t sum = mRanges.size();
+    for (auto const& e : mRanges)
+        sum += e.second - e.first;
+    return sum;
+}
+
 void RangeSet::checkInternalConsistency () const noexcept
 {
 #ifndef NDEBUG