diff --git a/alloc/linear.cpp b/alloc/linear.cpp
index 80ed26a4..1f784a62 100644
--- a/alloc/linear.cpp
+++ b/alloc/linear.cpp
@@ -73,7 +73,7 @@ linear::capacity (void) const
 
 //-----------------------------------------------------------------------------
 size_t
-linear::size (void) const
+linear::used (void) const
 {
     return m_cursor - m_begin;
 }
@@ -83,5 +83,5 @@ linear::size (void) const
 size_t
 linear::remain (void) const
 {
-    return capacity () - size ();
+    return capacity () - used ();
 }
diff --git a/alloc/linear.hpp b/alloc/linear.hpp
index 303789b4..d8724e86 100644
--- a/alloc/linear.hpp
+++ b/alloc/linear.hpp
@@ -38,7 +38,7 @@ namespace util { namespace alloc {
         void reset (void);
 
         size_t capacity (void) const;
-        size_t size     (void) const;
+        size_t used     (void) const;
         size_t remain   (void) const;
 
     protected:
diff --git a/alloc/stack.cpp b/alloc/stack.cpp
index b33a6d2d..436aa249 100644
--- a/alloc/stack.cpp
+++ b/alloc/stack.cpp
@@ -111,7 +111,7 @@ stack::capacity (void) const
 
 //-----------------------------------------------------------------------------
 size_t
-stack::size (void) const
+stack::used (void) const
 {
     return m_cursor - m_begin;
 }
@@ -121,5 +121,5 @@ stack::size (void) const
 size_t
 stack::remain (void) const
 {
-    return capacity () - size ();
+    return capacity () - used ();
 }
diff --git a/alloc/stack.hpp b/alloc/stack.hpp
index 055a6bec..0cedd583 100644
--- a/alloc/stack.hpp
+++ b/alloc/stack.hpp
@@ -40,7 +40,7 @@ namespace util { namespace alloc {
         void reset (void);
 
         size_t capacity (void) const;
-        size_t size     (void) const;
+        size_t used     (void) const;
         size_t remain   (void) const;
 
     private:
diff --git a/test/alloc/linear.cpp b/test/alloc/linear.cpp
index ec95ada1..338e3437 100644
--- a/test/alloc/linear.cpp
+++ b/test/alloc/linear.cpp
@@ -12,6 +12,8 @@ main (void)
     alignas (std::max_align_t) char memory[BUFFER_SIZE];
     util::alloc::linear store (std::begin (memory), std::end (memory));
 
+    tap.expect_eq (store.capacity (), BUFFER_SIZE, "bytes capacity matches");
+
     tap.expect_throw<std::bad_alloc> (
         [&] (void) { store.allocate (BUFFER_SIZE + 1, 1); },
         "excessive allocation throws bad_alloc"
@@ -22,6 +24,9 @@ main (void)
         "maximum allocation succeeds"
     );
 
+    tap.expect_eq (store.used (), BUFFER_SIZE, "bytes used matches");
+    tap.expect_eq (store.remain (), 0u, "bytes remain matches");
+
     tap.expect_throw<std::bad_alloc> (
         [&] (void) { store.allocate (1, 1); },
         "minimum allocation fails after exhaustion"
diff --git a/test/alloc/stack.cpp b/test/alloc/stack.cpp
index 24cca3a4..47356516 100644
--- a/test/alloc/stack.cpp
+++ b/test/alloc/stack.cpp
@@ -34,6 +34,8 @@ main (void)
 
     util::alloc::stack store (memory, memory + BUFFER_AVAILABLE);
 
+    tap.expect_eq (store.capacity (), BUFFER_AVAILABLE, "bytes capacity matches");
+
     // larger than total allocations should throw
     tap.expect_throw<std::bad_alloc> (
         [&store] (void) { store.allocate (BUFFER_AVAILABLE + 1, 1); },
@@ -56,6 +58,11 @@ main (void)
         [&store] (void) { store.allocate (BUFFER_REQUEST); },
         "bad_alloc thrown on exhaustion"
     );
+
+    // check byte counts are plausible. stacks use some extra memory for book
+    // keeping, so we need to use relational comparison rather than equality.
+    tap.expect_ge (store.used (), BUFFER_REQUEST, "bytes used matches");
+    tap.expect_le (store.remain (), BUFFER_AVAILABLE - BUFFER_REQUEST, "bytes remain matches");
     
     // try many allocations again after resetting the allocator to zero usage
     store.reset ();