diff --git a/package-lock.json b/package-lock.json
index 1509789f..fec7a796 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -32,6 +32,7 @@
         "dayjs": "^1.11.10",
         "embla-carousel-react": "^8.0.0-rc21",
         "lucide-react": "^0.290.0",
+        "math-expression-evaluator": "^2.0.5",
         "nanoid": "^5.0.4",
         "next": "^14.2.3",
         "next-s3-upload": "^0.3.4",
@@ -901,10 +902,9 @@
       }
     },
     "node_modules/@babel/runtime": {
-      "version": "7.23.2",
-      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.23.2.tgz",
-      "integrity": "sha512-mM8eg4yl5D6i3lu2QKPuPH4FArvJ8KhTofbE7jwMUv9KX5mBvwPAqnV3MlyBNqdp9RyRKP6Yck8TrfYrPvX3bg==",
-      "license": "MIT",
+      "version": "7.24.8",
+      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.24.8.tgz",
+      "integrity": "sha512-5F7SDGs1T72ZczbRwbGO9lQi0NLjQxzl6i4lJxLxfW9U5UluCSyEJeniWvnhl3/euNiqQVbo8zruhsDfid0esA==",
       "dependencies": {
         "regenerator-runtime": "^0.14.0"
       },
@@ -6455,6 +6455,11 @@
         "react": "^16.5.1 || ^17.0.0 || ^18.0.0"
       }
     },
+    "node_modules/math-expression-evaluator": {
+      "version": "2.0.5",
+      "resolved": "https://registry.npmjs.org/math-expression-evaluator/-/math-expression-evaluator-2.0.5.tgz",
+      "integrity": "sha512-C8Ifr3BpZ1E8ncWiHltndUkimvkzBwEiXPRyDJVxspo/G7zSN8tLHwFVfrGotvWzu2wuRkjnxaEayFblepmN5Q=="
+    },
     "node_modules/md5": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/md5/-/md5-2.3.0.tgz",
diff --git a/package.json b/package.json
index 17e66865..78eed291 100644
--- a/package.json
+++ b/package.json
@@ -38,6 +38,7 @@
     "dayjs": "^1.11.10",
     "embla-carousel-react": "^8.0.0-rc21",
     "lucide-react": "^0.290.0",
+    "math-expression-evaluator": "^2.0.5",
     "nanoid": "^5.0.4",
     "next": "^14.2.3",
     "next-s3-upload": "^0.3.4",
diff --git a/src/components/expense-form.tsx b/src/components/expense-form.tsx
index 758e93d1..63b13b97 100644
--- a/src/components/expense-form.tsx
+++ b/src/components/expense-form.tsx
@@ -52,6 +52,9 @@ import { match } from 'ts-pattern'
 import { DeletePopup } from './delete-popup'
 import { extractCategoryFromTitle } from './expense-form-actions'
 import { Textarea } from './ui/textarea'
+import Mexp from 'math-expression-evaluator'
+
+const mexp = new Mexp()
 
 export type Props = {
   group: NonNullable<Awaited<ReturnType<typeof getGroup>>>
@@ -245,6 +248,7 @@ export function ExpenseForm({
   }
 
   const [isIncome, setIsIncome] = useState(Number(form.getValues().amount) < 0)
+  const [evaluatedAmount, setEvaluatedAmount] = useState('0')
   const sExpense = isIncome ? 'income' : 'expense'
   const sPaid = isIncome ? 'received' : 'paid'
 
@@ -322,47 +326,57 @@ export function ExpenseForm({
                     <span>{group.currency}</span>
                     <FormControl>
                       <Input
-                        className="text-base max-w-[120px]"
+                        className="text-base"
                         type="text"
                         inputMode="decimal"
                         placeholder="0.00"
                         onChange={(event) => {
-                          const v = enforceCurrencyPattern(event.target.value)
-                          const income = Number(v) < 0
-                          setIsIncome(income)
-                          if (income) form.setValue('isReimbursement', false)
+                          let v = (event.target.value)
+                          if (v === ''){
+                            setEvaluatedAmount('0')
+                          }
+                          else{
+                            try{
+                              const evaluatedValue = Number(mexp.eval(v)).toFixed(2).replace(/\.?0+$/, '') // replace trailing zeros
+                              setEvaluatedAmount(evaluatedValue)
+                              const income = Number(evaluatedValue) < 0
+                              setIsIncome(income)
+                              if (income) form.setValue('isReimbursement', false)
+                            }
+                            catch{
+                              setEvaluatedAmount('Invalid Expression')
+                            }
+                          }
                           onChange(v)
                         }}
-                        onFocus={(e) => {
-                          // we're adding a small delay to get around safaris issue with onMouseUp deselecting things again
-                          const target = e.currentTarget
-                          setTimeout(() => target.select(), 1)
-                        }}
                         {...field}
                       />
                     </FormControl>
                   </div>
                   <FormMessage />
+                    <div className="flex flex-row gap-2 items-center justify-between">
+                      <div className="text-white/50 pl-5">
+                        {' = ' + evaluatedAmount}
+                      </div>
+                      {!isIncome && (
+                      <FormField
+                        control={form.control}
+                        name="isReimbursement"
+                        render={({ field }) => (
+                          <FormItem className="flex flex-row gap-2 items-center space-y-0">
+                            <FormControl>
+                              <Checkbox
+                                checked={field.value}
+                                onCheckedChange={field.onChange}
+                              />
+                            </FormControl>
+                              <FormLabel>Reimbursement</FormLabel>
+                          </FormItem>
 
-                  {!isIncome && (
-                    <FormField
-                      control={form.control}
-                      name="isReimbursement"
-                      render={({ field }) => (
-                        <FormItem className="flex flex-row gap-2 items-center space-y-0 pt-2">
-                          <FormControl>
-                            <Checkbox
-                              checked={field.value}
-                              onCheckedChange={field.onChange}
-                            />
-                          </FormControl>
-                          <div>
-                            <FormLabel>This is a reimbursement</FormLabel>
-                          </div>
-                        </FormItem>
-                      )}
-                    />
-                  )}
+                        )}
+                      />
+                    )}
+                  </div>
                 </FormItem>
               )}
             />
diff --git a/src/lib/schemas.ts b/src/lib/schemas.ts
index 9578b025..c58b65f4 100644
--- a/src/lib/schemas.ts
+++ b/src/lib/schemas.ts
@@ -1,5 +1,8 @@
 import { SplitMode } from '@prisma/client'
 import * as z from 'zod'
+import Mexp from 'math-expression-evaluator'
+
+const mexp = new Mexp()
 
 export const groupFormSchema = z
   .object({
@@ -51,7 +54,7 @@ export const expenseFormSchema = z
         [
           z.number(),
           z.string().transform((value, ctx) => {
-            const valueAsNumber = Number(value)
+            const valueAsNumber = Number(mexp.eval(value).toFixed(2).replace(/\.?0+$/, ''))
             if (Number.isNaN(valueAsNumber))
               ctx.addIssue({
                 code: z.ZodIssueCode.custom,