diff --git a/crates/engine/src/cmd/create.rs b/crates/engine/src/cmd/create.rs
--- a/crates/engine/src/cmd/create.rs
+++ b/crates/engine/src/cmd/create.rs
@@ -588,11 +588,12 @@ fn grid_group(s: &mut Session, label: &str, (paths, bbox_angle): (Vec<PathData>,
 }
 
 /// A grid's divider count `count` (an error unless it is a number or null; 5 unless it is a JSON
-/// integer of 0 or more, so 4.0 and 2.5 give 5; at most 999) with its skew `key` in percent (0 when
+/// whole number of 0 or more, so 4.0 gives 4 and 2.5 gives 5; at most 999) with its skew `key` in percent (0 when
 /// absent, clamped to ±[`shapes::GRID_SKEW_MAX`]).
 fn dividers(p: &Value, count: &str, key: &str, cmd: &str) -> Result<(u32, f64)> {
     check_numbers(p, &[count], cmd)?;
-    let n = p.get(count).and_then(Value::as_u64).unwrap_or(5).min(999) as u32;
+    let whole = |v: &Value| v.as_u64().or_else(|| v.as_f64().filter(|f| f.is_finite() && *f >= 0.0 && f.fract() == 0.0).map(|f| f as u64));
+    let n = p.get(count).and_then(whole).unwrap_or(5).min(999) as u32;
     let skew = match p.get(key) {
         None | Some(Value::Null) => 0.0,
         Some(v) => v.as_f64().filter(|v| v.is_finite()).ok_or_else(|| bad(cmd, format!("`{key}` must be a number")))?,
diff --git a/crates/engine/src/tests/draw2.rs b/crates/engine/src/tests/draw2.rs
--- a/crates/engine/src/tests/draw2.rs
+++ b/crates/engine/src/tests/draw2.rs
@@ -1076,6 +1076,22 @@ fn polar_grid_options_compound_fill_and_skew() {
     assert!(tips(&inward)[1..].iter().all(|t| t.x < 50.0), "counterclockwise of the top: {:?}", tips(&inward));
 }
 
+/// A divider count written as a whole float (`3.0`) is the same as `3`; a fraction gives the default 5.
+#[test]
+fn grid_divider_counts_accept_whole_floats() {
+    let mut s = session();
+    let size = json!({"x": 0, "y": 0, "width": 100, "height": 100});
+    let float = grid(&mut s, "shape.rectangularGrid", with(&size, json!({"rows": 3.0, "columns": 3.0})));
+    let int = grid(&mut s, "shape.rectangularGrid", with(&size, json!({"rows": 3, "columns": 3})));
+    assert_eq!(float.len(), int.len());
+    assert_eq!(float.len(), 7);
+    let float = grid(&mut s, "shape.polarGrid", with(&size, json!({"concentric": 2.0, "radial": 3.0})));
+    let int = grid(&mut s, "shape.polarGrid", with(&size, json!({"concentric": 2, "radial": 3})));
+    assert_eq!(float.len(), int.len());
+    let frac = grid(&mut s, "shape.rectangularGrid", with(&size, json!({"rows": 2.5, "columns": 2.5})));
+    assert_eq!(frac.len(), 11);
+}
+
 /// The grid options are checked: a divider count or a skew is a number and a switch true or false,
 /// or the command fails without an undo step.
 #[test]