Definitely still WIP, this lets you group calc inputs into equivalents

src/pages/tools/number/generic-calc/data/area_volume.ts

@@ -0,0 +1,50 @@
+import type { GenericCalcType } from './types';
+
+export const areaSphere: GenericCalcType = {
+  title: 'Area of a Sphere',
+  name: 'area-sphere',
+  description: 'Area of a Sphere',
+  formula: 'A = 4 * pi * r**2',
+  selections: [],
+  variables: [
+    {
+      name: 'A',
+      title: 'Area',
+      unit: 'mm2'
+    },
+    {
+      name: 'r',
+      title: 'Radius',
+      unit: 'mm',
+      default: 1
+    }
+  ]
+};
+
+export const volumeSphere: GenericCalcType = {
+  title: 'Volume of a Sphere',
+  name: 'volume-sphere',
+  description: 'Volume of a Sphere',
+  formula: 'v = (4/3) * pi * r**3',
+  selections: [],
+  variables: [
+    {
+      name: 'v',
+      title: 'Volume',
+      unit: 'mm3'
+    },
+    {
+      name: 'r',
+      title: 'Radius',
+      unit: 'mm',
+      default: 1,
+      alternates: [
+        {
+          title: 'Diameter',
+          formula: 'x = 2 * v',
+          unit: 'mm'
+        }
+      ]
+    }
+  ]
+};