diff --git a/api/src/org/labkey/api/data/ConvertHelper.java b/api/src/org/labkey/api/data/ConvertHelper.java
index 516c30dbc57..4f104bf92f6 100644
--- a/api/src/org/labkey/api/data/ConvertHelper.java
+++ b/api/src/org/labkey/api/data/ConvertHelper.java
@@ -89,6 +89,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.concurrent.Callable;
 
 
 /**
@@ -1371,9 +1372,75 @@ public void testMiscConversions()
             assertEquals(home.getRowId(), ((Container)ConvertUtils.convert(home.getId(), Container.class)).getRowId());
             assertEquals(home.getId(), ConvertUtils.convert(home, String.class));
         }
+
+        Exception ex(Callable c)
+        {
+            try
+            {
+                c.call();
+                return null;
+            }
+            catch (Exception x)
+            {
+                return x;
+            }
+        }
+
+        @Test
+        public void testNumber()
+        {
+            // fractions -> integer
+            assertTrue(ex(()->JdbcType.BIGINT.convert("5.0001")) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.BIGINT.convert(new BigDecimal("5.0001"))) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.BIGINT.convert(5.0001f)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.BIGINT.convert(5.0001d)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.BIGINT.convert(5.0001d)).getMessage().startsWith("Could not convert '"));
+
+            assertTrue(ex(()->JdbcType.INTEGER.convert("5.0001")) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.INTEGER.convert(new BigDecimal("5.0001"))) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.INTEGER.convert(5.0001f)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.INTEGER.convert(5.0001d)) instanceof ConversionException);
+
+            assertTrue(ex(()->JdbcType.SMALLINT.convert("5.0001")) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.SMALLINT.convert(new BigDecimal("5.0001"))) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.SMALLINT.convert(5.0001f)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.SMALLINT.convert(5.0001d)) instanceof ConversionException);
+
+            assertTrue(ex(()->PropertyType.BIGINT.convert("5.0001")) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.BIGINT.convert(new BigDecimal("5.0001"))) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.BIGINT.convert(5.0001f)) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.BIGINT.convert(5.0001d)) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.BIGINT.convert(5.0001d)).getMessage().startsWith("Could not convert '"));
+
+            assertTrue(ex(()->PropertyType.INTEGER.convert("5.0001")) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert(new BigDecimal("5.0001"))) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert(5.0001f)) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert(5.0001d)) instanceof ConversionException);
+
+            assertTrue(ex(()->ConvertUtils.convert("5.0001", Long.class)) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert(new BigDecimal("5.0001"), Long.class)) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert(5.0001f, Long.class)) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert(5.0001d, Long.class)) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert(5.0001d)).getMessage().startsWith("Could not convert '"));
+
+            // OOR
+            assertTrue(ex(()->JdbcType.TINYINT.convert(Long.MAX_VALUE)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.TINYINT.convert(10_000_000_000d)) instanceof ConversionException);
+            assertTrue(ex(()->JdbcType.TINYINT.convert("10000000000")) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert(Long.MAX_VALUE)) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert(10_000_000_000d)) instanceof ConversionException);
+            assertTrue(ex(()->PropertyType.INTEGER.convert("10000000000")) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert(10_000_000_000d, Short.class)) instanceof ConversionException);
+            assertTrue(ex(()->ConvertUtils.convert("10000000000", Short.class)) instanceof ConversionException);
+            assertEquals(Long.MAX_VALUE, ConvertUtils.convert(BigDecimal.valueOf(Long.MAX_VALUE), Long.class));
+            assertEquals(Long.MIN_VALUE, ConvertUtils.convert(BigDecimal.valueOf(Long.MIN_VALUE), Long.class));
+            // precision of Double is not high enough for this equality test to work for any random integer this large
+            assertEquals(Long.MAX_VALUE, ConvertUtils.convert(Double.valueOf(Long.MAX_VALUE), Long.class));
+            assertEquals(Long.MIN_VALUE, ConvertUtils.convert(Double.valueOf(Long.MIN_VALUE), Long.class));
+        }
     }
 
-    // Note: Keep in sync with LabKeySiteWrapper.getConversionErrorMessage()
+// Note: Keep in sync with LabKeySiteWrapper.getConversionErrorMessage()
     // Example: "Could not convert value '2.34' (Double) for Boolean field 'Medical History.Dep Diagnosed in Last 18 Months'"
     public static String getStandardConversionErrorMessage(Object value, String fieldName, Class<?> expectedClass)
     {
diff --git a/api/src/org/labkey/api/data/JdbcType.java b/api/src/org/labkey/api/data/JdbcType.java
index 771dc7387aa..9b5184744e6 100644
--- a/api/src/org/labkey/api/data/JdbcType.java
+++ b/api/src/org/labkey/api/data/JdbcType.java
@@ -55,9 +55,7 @@ public enum JdbcType implements SimpleConvert
         @Override
         protected Object _fromNumber(Number n)
         {
-            if (n.doubleValue() == (double) n.longValue())
-                return n.longValue();
-            return null; // fallback
+            return _toLong(n);
         }
 
         @Override
@@ -730,15 +728,22 @@ private static Boolean _toBoolean(Number n)
             return Boolean.FALSE;
         if (1 == n.intValue())
             return Boolean.TRUE;
-
         throw new ConversionException("Expected boolean value");
     }
 
+    private static Long _toLong(Number n)
+    {
+        if (n instanceof Long l)
+            return l;
+        if (!(n instanceof BigDecimal) && n.doubleValue() == (double)n.longValue())
+            return n.longValue();
+        return ConvertHelper.convert(n, Long.class);
+    }
 
     private static Integer _toInt(Number n)
     {
         if (n.doubleValue() != (double)n.intValue())
-            throw new ConversionException("Expected integer value");
+            throw new ConversionException("Could not convert '" + n + "' to an integer");
         return n.intValue();
     }
 
@@ -746,7 +751,7 @@ private static Integer _toInt(Number n)
     private static Short _toShort(Number n)
     {
         if (n.doubleValue() != (double)n.shortValue())
-            throw new ConversionException("Expected integer value");
+            throw new ConversionException("Could not convert '" + n + "' to a short integer");
         return n.shortValue();
     }