diff --git a/src/Modal.vue b/src/Modal.vue
index ca13252..9f96d49 100644
--- a/src/Modal.vue
+++ b/src/Modal.vue
@@ -96,7 +96,8 @@
         default: 600,
         validator (value) {
           if (typeof value === 'string') {
-            return value.charAt(value.length-1) === '%' && !isNaN(parseFloat(value))
+            return value.charAt(value.length-1) === '%'
+              && !isNaN(parseFloat(value))
           }
 
           if (typeof value === 'number') {
@@ -109,7 +110,8 @@
         default: 300,
         validator (value) {
           if (typeof value === 'string') {
-            return value === 'auto' || (value.charAt(value.length-1) === '%' && !isNaN(parseFloat(value)))
+            return (value.charAt(value.length-1) === '%'
+              && !isNaN(parseFloat(value)))
           }
 
           if (typeof value === 'number') {
diff --git a/src/floatStringParser.js b/src/floatStringParser.js
new file mode 100644
index 0000000..a34793b
--- /dev/null
+++ b/src/floatStringParser.js
@@ -0,0 +1,73 @@
+// Parses string with float number and suffix:
+// "0.001" => { type: "px", value: 0.001 }
+// "0.001px" => { type: "px", value: 0.001 }
+// "0.1%" => { type: "px", value: 0.1 }
+// "foo"  => { type: "", value: "foo" }
+
+var floatRegexp = '[-+]?[0-9]*\.?[0-9]+'
+
+var types = [
+  {
+    name: 'px',
+    regexp: new RegExp(`^${floatRegexp}px\$`)
+  }, 
+  {
+    name: '%',
+    regexp: new RegExp(`^${floatRegexp}%\$`)
+  },
+  // Fallback option:
+  // If no suffix specified, assign to px
+  {
+    name: 'px',
+    regexp: new RegExp(`^${floatRegexp}\$`)
+  }
+]
+
+var getType = (value) => {
+  for (var i = 0; i < types.length; i++) {
+    let type = types[i]
+    if (type.regexp.test(value)) {
+      return {
+        type: type.name,
+        value: parseFloat(value)
+      }
+    }
+  }
+
+  return {
+    type: '',
+    value: value
+  }
+}
+
+var parse = (value) => {
+  switch (typeof value) {
+    case 'number':
+      return { type: 'px', value }
+    case 'string':
+      return getType(value)
+    default: 
+      return { type: '', value }
+  }
+}
+
+export default parse
+
+/// tests
+/*
+console.log(parse(10))
+console.log(parse(10.10))
+console.log(parse(-10))
+
+console.log(parse('5%'))
+console.log(parse('-5%'))
+console.log(parse('5.123%'))
+
+console.log(parse('5px'))
+console.log(parse('-5px'))
+console.log(parse('5.123px'))
+
+console.log(parse("adasd%"))
+console.log(parse(""))
+console.log(parse("+2-3px")) // fails
+*/
\ No newline at end of file