diff --git a/webapp/IronCalc/src/components/SheetTabBar/SheetTabBar.tsx b/webapp/IronCalc/src/components/SheetTabBar/SheetTabBar.tsx
index f250a30..dd3e592 100644
--- a/webapp/IronCalc/src/components/SheetTabBar/SheetTabBar.tsx
+++ b/webapp/IronCalc/src/components/SheetTabBar/SheetTabBar.tsx
@@ -98,7 +98,7 @@ function SheetTabBar(props: SheetTabBarProps) {
             <IronCalcLogo />
           </LogoLink>
         </Tooltip>
-        <Tooltip title={t("navigation.settings")}>
+        <Tooltip title={t("workbook_settings.open_settings")}>
           <StyledButton
             $pressed={false}
             onClick={() => {
@@ -124,7 +124,6 @@ function SheetTabBar(props: SheetTabBarProps) {
       <WorkbookSettingsDialog
         open={workbookSettingsOpen}
         onClose={() => setWorkbookSettingsOpen(false)}
-        onExited={() => setWorkbookSettingsOpen(false)}
       />
     </Container>
   );
diff --git a/webapp/IronCalc/src/components/WorkbookSettings/WorkbookSettingsDialog.tsx b/webapp/IronCalc/src/components/WorkbookSettings/WorkbookSettingsDialog.tsx
index 8fa4408..85b9303 100644
--- a/webapp/IronCalc/src/components/WorkbookSettings/WorkbookSettingsDialog.tsx
+++ b/webapp/IronCalc/src/components/WorkbookSettings/WorkbookSettingsDialog.tsx
@@ -1,29 +1,65 @@
 import styled from "@emotion/styled";
-import { Dialog } from "@mui/material";
-import { X } from "lucide-react";
+import {
+  Autocomplete,
+  Box,
+  Dialog,
+  FormControl,
+  MenuItem,
+  Select,
+  TextField,
+} from "@mui/material";
+import { Check, X } from "lucide-react";
+import { useState } from "react";
 import { useTranslation } from "react-i18next";
 import { theme } from "../../theme";
 
 type WorkbookSettingsDialogProps = {
   open: boolean;
   onClose: () => void;
-  onExited: () => void;
+  initialLocale?: string;
+  initialTimezone?: string;
+  onSave?: (locale: string, timezone: string) => void;
 };
 
 const WorkbookSettingsDialog = (properties: WorkbookSettingsDialogProps) => {
   const { t } = useTranslation();
+  const [selectedLocale, setSelectedLocale] = useState<string>(
+    properties.initialLocale || "",
+  );
+  const [selectedTimezone, setSelectedTimezone] = useState<string>(
+    properties.initialTimezone || "",
+  );
 
-  const handleClose = () => {
+  const handleSave = () => {
+    if (properties.onSave && selectedLocale && selectedTimezone) {
+      properties.onSave(selectedLocale, selectedTimezone);
+    }
     properties.onClose();
   };
 
+  const timezones = [
+    "Berlin, Germany (GMT+1)",
+    "New York, USA (GMT-5)",
+    "Tokyo, Japan (GMT+9)",
+    "London, UK (GMT+0)",
+    "Sydney, Australia (GMT+10)",
+  ];
+
+  const locales = ["en-US", "en-GB", "de-DE", "fr-FR", "es-ES"];
+
   return (
-    <StyledDialog open={properties.open} onClose={properties.onClose}>
+    <StyledDialog
+      open={properties.open}
+      onClose={(_event, reason) => {
+        if (reason === "backdropClick" || reason === "escapeKeyDown") {
+          properties.onClose();
+        }
+      }}
+    >
       <StyledDialogTitle>
         {t("workbook_settings.title")}
         <Cross
-          onClick={handleClose}
-          title={t("workbook_settings.close")}
+          onClick={properties.onClose}
           tabIndex={0}
           onKeyDown={(event) => {
             if (event.key === "Enter") {
@@ -34,17 +70,140 @@ const WorkbookSettingsDialog = (properties: WorkbookSettingsDialogProps) => {
           <X />
         </Cross>
       </StyledDialogTitle>
-      <StyledDialogContent>
-        {/* Settings content will go here */}
+
+      <StyledDialogContent
+        onClick={(event) => event.stopPropagation()}
+        onMouseDown={(event) => event.stopPropagation()}
+      >
+        <StyledSectionTitle>
+          {t("workbook_settings.locale_and_timezone.title")}
+        </StyledSectionTitle>
+        <FieldWrapper>
+          <StyledLabel htmlFor="locale">
+            {t("workbook_settings.locale_and_timezone.locale_label")}
+          </StyledLabel>
+          <FormControl fullWidth>
+            <StyledSelect
+              id="locale"
+              value={selectedLocale}
+              onChange={(event) => {
+                setSelectedLocale(event.target.value as string);
+              }}
+              displayEmpty
+              MenuProps={{
+                PaperProps: {
+                  sx: menuPaperStyles,
+                },
+                TransitionProps: {
+                  timeout: 0,
+                },
+              }}
+            >
+              {locales.map((locale) => {
+                const isSelected = locale === selectedLocale;
+                return (
+                  <StyledMenuItem
+                    key={locale}
+                    value={locale}
+                    $isSelected={isSelected}
+                  >
+                    {locale}
+                  </StyledMenuItem>
+                );
+              })}
+            </StyledSelect>
+            <HelperBox>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.locale_example1")}
+                <RowValue>1,234.56</RowValue>
+              </Row>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.locale_example2")}
+                <RowValue>12/31/2025</RowValue>
+              </Row>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.locale_example3")}
+                <RowValue>11/23/2025 09:21:06 PM</RowValue>
+              </Row>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.locale_example4")}
+                <RowValue>Monday</RowValue>
+              </Row>
+            </HelperBox>
+          </FormControl>
+        </FieldWrapper>
+        <FieldWrapper>
+          <StyledLabel htmlFor="timezone">
+            {t("workbook_settings.locale_and_timezone.timezone_label")}
+          </StyledLabel>
+          <FormControl fullWidth>
+            <StyledAutocomplete
+              id="timezone"
+              value={selectedTimezone}
+              onChange={(_event, newValue) => {
+                setSelectedTimezone((newValue as string) || "");
+              }}
+              options={timezones}
+              renderInput={(params) => <TextField {...params} />}
+              renderOption={(props, option) => {
+                const isSelected = option === selectedTimezone;
+                return (
+                  <StyledMenuItem
+                    {...props}
+                    key={option as string}
+                    $isSelected={isSelected}
+                  >
+                    {option as string}
+                  </StyledMenuItem>
+                );
+              }}
+              disableClearable
+              slotProps={{
+                paper: {
+                  sx: menuPaperStyles,
+                },
+                popper: {
+                  sx: {
+                    "& .MuiAutocomplete-paper": {
+                      transition: "none !important",
+                    },
+                  },
+                },
+                popupIndicator: {
+                  disableRipple: true,
+                },
+              }}
+            />
+            <HelperBox>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.timezone_example1")}
+                <RowValue>23/11/2025</RowValue>
+              </Row>
+              <Row>
+                {t("workbook_settings.locale_and_timezone.timezone_example2")}
+                <RowValue>11/23/2025 09:21:06 PM</RowValue>
+              </Row>
+            </HelperBox>
+          </FormControl>
+        </FieldWrapper>
       </StyledDialogContent>
+
+      <DialogFooter>
+        <StyledButton onClick={handleSave} tabIndex={0}>
+          <Check
+            style={{ width: "16px", height: "16px", marginRight: "8px" }}
+          />
+          {t("num_fmt.save")}
+        </StyledButton>
+      </DialogFooter>
     </StyledDialog>
   );
 };
 
 const StyledDialog = styled(Dialog)`
   & .MuiPaper-root {
-    max-width: 400px;
-    min-width: 280px;
+    max-width: 320px;
+    min-width: 320px;
     border-radius: 8px;
     padding: 0px;
   }
@@ -81,8 +240,182 @@ const Cross = styled("div")`
 `;
 
 const StyledDialogContent = styled("div")`
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
   font-size: 12px;
   margin: 12px;
 `;
 
+const StyledSectionTitle = styled("h1")`
+  font-size: 14px;
+  font-weight: 600;
+  font-family: Inter;
+  margin: 0px;
+  color: ${theme.palette.text.primary};
+`;
+
+const StyledSelect = styled(Select)`
+  font-size: 12px;
+  height: 32px;
+  & .MuiInputBase-root {
+    padding: 0px !important;
+  }
+  & .MuiInputBase-input {
+    font-size: 12px;
+    height: 20px;
+    padding-right: 0px !important;
+    margin: 0px;
+  }
+  & .MuiSelect-select {
+    padding: 8px 32px 8px 8px !important;
+    font-size: 12px;
+  }
+  & .MuiSvgIcon-root {
+    right: 4px !important;
+  }
+`;
+
+const HelperBox = styled("div")`
+  display: flex;
+  flex-direction: column;
+  align-items: start;
+  justify-content: center;
+  gap: 2px;
+  box-sizing: border-box;
+  border: 1px solid ${theme.palette.grey["300"]};
+  font-family: Inter;
+  width: 100%;
+  height: 100%;
+  margin-top: 8px;
+  background-color: ${theme.palette.grey["100"]};
+  border-radius: 4px;
+  padding: 8px;
+`;
+
+const Row = styled("div")`
+  display: flex;
+  flex-direction: row;
+  gap: 4px;
+  width: 100%;
+  justify-content: space-between;
+  color: ${theme.palette.grey[700]};
+`;
+
+const RowValue = styled("span")`
+  font-size: 12px;
+  font-family: Inter;
+  font-weight: normal;
+  color: ${theme.palette.grey[500]};
+`;
+
+const StyledAutocomplete = styled(Autocomplete)`
+  & .MuiInputBase-root {
+    padding: 0px !important;
+    height: 32px;
+  }
+  & .MuiInputBase-input {
+    font-size: 12px;
+    height: 20px;
+    padding: 0px;
+    padding-right: 0px !important;
+    margin: 0px;
+  }
+  & .MuiAutocomplete-popupIndicator:hover {
+    background-color: transparent !important;
+  }
+  & .MuiAutocomplete-popupIndicator {
+    & .MuiTouchRipple-root {
+      display: none;
+    }
+  }
+  & .MuiOutlinedInput-root .MuiAutocomplete-endAdornment {
+    right: 4px;
+  }
+  & .MuiOutlinedInput-root .MuiAutocomplete-input {
+    padding: 8px !important;
+  }
+`;
+
+const menuPaperStyles = {
+  boxSizing: "border-box",
+  marginTop: "4px",
+  padding: "4px",
+  borderRadius: "8px",
+  transition: "none !important",
+  "& .MuiList-padding": {
+    padding: 0,
+  },
+  "& .MuiList-root": {
+    padding: 0,
+  },
+  "& .MuiAutocomplete-noOptions": {
+    padding: "8px",
+    fontSize: "12px",
+    fontFamily: "Inter",
+  },
+  "& .MuiMenuItem-root": {
+    height: "32px !important",
+    padding: "8px !important",
+    minHeight: "32px !important",
+  },
+};
+
+const StyledMenuItem = styled(MenuItem)<{ $isSelected?: boolean }>`
+  padding: 8px !important;
+  height: 32px !important;
+  min-height: 32px !important;
+  border-radius: 4px;
+  display: flex;
+  align-items: center;
+  font-size: 12px;
+  background-color: ${({ $isSelected }) =>
+    $isSelected ? theme.palette.grey[50] : "transparent"} !important;
+  &:hover {
+    background-color: ${theme.palette.grey[50]} !important;
+  }
+`;
+
+const FieldWrapper = styled(Box)`
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  gap: 6px;
+`;
+
+const StyledLabel = styled("label")`
+  font-size: 12px;
+  font-family: "Inter";
+  font-weight: 500;
+  color: ${theme.palette.text.primary};
+  display: block;
+`;
+
+const DialogFooter = styled("div")`
+  color: ${theme.palette.grey[700]};
+  display: flex;
+  align-items: center;
+  border-top: 1px solid ${theme.palette.grey["300"]};
+  font-family: Inter;
+  justify-content: flex-end;
+  padding: 12px;
+`;
+
+const StyledButton = styled("div")`
+  cursor: pointer;
+  color: ${theme.palette.common.white};
+  background: ${theme.palette.primary.main};
+  padding: 0px 10px;
+  height: 36px;
+  line-height: 36px;
+  border-radius: 4px;
+  display: flex;
+  align-items: center;
+  font-family: "Inter";
+  font-size: 14px;
+  &:hover {
+    background: ${theme.palette.primary.dark};
+  }
+`;
+
 export default WorkbookSettingsDialog;
diff --git a/webapp/IronCalc/src/locale/en_us.json b/webapp/IronCalc/src/locale/en_us.json
index 1e0cf02..8573920 100644
--- a/webapp/IronCalc/src/locale/en_us.json
+++ b/webapp/IronCalc/src/locale/en_us.json
@@ -169,7 +169,19 @@
     "resize_drawer": "Resize drawer"
   },
   "workbook_settings": {
+    "open_settings": "Open settings",
     "title": "Workbook Settings",
-    "close": "Close dialog"
+    "close": "Close dialog",
+    "locale_and_timezone": {
+      "title": "Locale & Timezone",
+      "locale_label": "Locale",
+      "locale_example1": "Number",
+      "locale_example2": "Date",
+      "locale_example3": "Date and Time",
+      "locale_example4": "First day of the week",
+      "timezone_label": "Timezone",
+      "timezone_example1": "TODAY()",
+      "timezone_example2": "NOW()"
+    }
   }
 }