diff --git a/app/javascript/controllers/onboarding_controller.js b/app/javascript/controllers/onboarding_controller.js
index 7e410d916..19c3c9ee8 100644
--- a/app/javascript/controllers/onboarding_controller.js
+++ b/app/javascript/controllers/onboarding_controller.js
@@ -2,16 +2,20 @@ import { Controller } from "@hotwired/stimulus";
 
 // Connects to data-controller="onboarding"
 export default class extends Controller {
-  static targets = ["nameField", "monikerRadio"]
+  static targets = ["nameField", "monikerRadio", "countryField", "currencyField"]
   static values = {
     householdNameLabel: String,
     householdNamePlaceholder: String,
     groupNameLabel: String,
-    groupNamePlaceholder: String
+    groupNamePlaceholder: String,
+    country: String,
+    countryCurrencies: Object,
+    currencyOverride: Boolean
   }
 
   connect() {
     this.updateNameFieldForCurrentMoniker();
+    this.applyBrowserLocaleDefaults();
   }
 
   setLocale(event) {
@@ -30,6 +34,43 @@ export default class extends Controller {
     document.documentElement.setAttribute("data-theme", event.target.value);
   }
 
+  applyBrowserLocaleDefaults() {
+    const browserCountry = this.browserCountry();
+
+    if (this.hasCountryFieldTarget && browserCountry && this.countryFieldTarget.value === "US" && this.hasCountryOption(browserCountry)) {
+      this.countryFieldTarget.value = browserCountry;
+    }
+
+    if (this.hasCurrencyFieldTarget && !this.currencyOverrideValue) {
+      const country = this.countryValue || (this.hasCountryFieldTarget ? this.countryFieldTarget.value : null) || browserCountry;
+      const currency = this.currencyForCountry(country);
+
+      if (currency && this.hasCurrencyOption(currency)) {
+        this.currencyFieldTarget.value = currency;
+      }
+    }
+  }
+
+  browserCountry() {
+    try {
+      return new Intl.Locale(navigator.language).maximize().region;
+    } catch (_error) {
+      return null;
+    }
+  }
+
+  currencyForCountry(country) {
+    return (this.hasCountryCurrenciesValue ? this.countryCurrenciesValue : {})[country?.toUpperCase()];
+  }
+
+  hasCountryOption(country) {
+    return Array.from(this.countryFieldTarget.options).some((option) => option.value === country);
+  }
+
+  hasCurrencyOption(currency) {
+    return Array.from(this.currencyFieldTarget.options).some((option) => option.value === currency);
+  }
+
   updateNameFieldForCurrentMoniker(event = null) {
     if (!this.hasNameFieldTarget) {
       return;
diff --git a/app/models/family.rb b/app/models/family.rb
index b0f7f2ec2..c2ae27dca 100644
--- a/app/models/family.rb
+++ b/app/models/family.rb
@@ -151,7 +151,28 @@ class Family < ApplicationRecord
   before_validation :normalize_enabled_currencies!
 
   def primary_currency_code
-    normalize_currency_code(currency) || "USD"
+    self.class.normalize_currency_code(currency) || "USD"
+  end
+
+  def default_currency_for_country
+    self.class.default_currency_for_country(country)
+  end
+
+  def self.default_currency_for_country(country)
+    country_currency = ISO3166::Country.new(country.to_s.upcase)&.currency_code
+    normalize_currency_code(country_currency) || "USD"
+  end
+
+  def self.default_currency_by_country
+    LanguagesHelper::COUNTRY_MAPPING.keys.index_with { |country| default_currency_for_country(country) }
+  end
+
+  def self.normalize_currency_code(value)
+    return if value.blank?
+
+    Money::Currency.new(value).iso_code
+  rescue Money::Currency::UnknownCurrencyError, ArgumentError
+    nil
   end
 
   def custom_enabled_currencies?
@@ -491,15 +512,7 @@ class Family < ApplicationRecord
     end
 
     def normalize_currency_codes(values)
-      Array(values).filter_map { |value| normalize_currency_code(value) }.uniq
-    end
-
-    def normalize_currency_code(value)
-      return if value.blank?
-
-      Money::Currency.new(value).iso_code
-    rescue Money::Currency::UnknownCurrencyError, ArgumentError
-      nil
+      Array(values).filter_map { |value| self.class.normalize_currency_code(value) }.uniq
     end
 
     # Not a plain `inclusion: { in: ActiveSupport::TimeZone.all.map(&:name) }`
diff --git a/app/views/onboardings/preferences.html.erb b/app/views/onboardings/preferences.html.erb
index a6e0c68a0..e804979c1 100644
--- a/app/views/onboardings/preferences.html.erb
+++ b/app/views/onboardings/preferences.html.erb
@@ -8,7 +8,15 @@
   <%= render "onboardings/logout" %>
 <% end %>
 
-<div class="grow max-w-lg w-full mx-auto bg-surface flex flex-col justify-center md:py-0 py-6 px-4 md:px-0" data-controller="onboarding">
+<% currency_override = Family.normalize_currency_code(params[:currency]) %>
+<% saved_currency = @user.family.primary_currency_code if @user.set_onboarding_preferences_at? %>
+<% selected_currency = currency_override || saved_currency || @user.family.default_currency_for_country %>
+
+<div class="grow max-w-lg w-full mx-auto bg-surface flex flex-col justify-center md:py-0 py-6 px-4 md:px-0"
+  data-controller="onboarding"
+  data-onboarding-country-value="<%= @user.family.country %>"
+  data-onboarding-country-currencies-value="<%= Family.default_currency_by_country.to_json %>"
+  data-onboarding-currency-override-value="<%= currency_override.present? || saved_currency.present? %>">
   <div>
     <div class="space-y-1 mb-6">
       <h1 class="text-2xl font-medium"><%= t(".title") %></h1>
@@ -19,10 +27,10 @@
       <div class="bg-container p-4 rounded-lg flex gap-8 shadow-border-xs">
         <div class="space-y-2">
           <%= tag.p t(".example"), class: "text-secondary text-sm" %>
-          <%= tag.p format_money(Money.new(2325.25, params[:currency] || @user.family.currency)), class: "text-primary font-medium text-2xl" %>
+          <%= tag.p format_money(Money.new(2325.25, selected_currency)), class: "text-primary font-medium text-2xl" %>
           <p class="text-sm">
-            <span class="text-green-500 font-medium">+<%= format_money(Money.new(78.90, params[:currency] || @user.family.currency)) %></span>
-            <span class="text-green-500 font-medium">(+<%= format_money(Money.new(6.39, params[:currency] || @user.family.currency)) %>)</span>
+            <span class="text-green-500 font-medium">+<%= format_money(Money.new(78.90, selected_currency)) %></span>
+            <span class="text-green-500 font-medium">(+<%= format_money(Money.new(6.39, selected_currency)) %>)</span>
             <span class="text-secondary">as of <%= format_date(Date.parse("2024-10-23"), :default, format_code: params[:date_format] || @user.family.date_format) %></span>
           </p>
         </div>
@@ -81,8 +89,8 @@
 
           <%= family_form.select :currency,
                                  Money::Currency.as_options.map { |currency| [ "#{currency.name} (#{currency.iso_code})", currency.iso_code ] },
-                                 { label: t(".currency"), required: true, selected: params[:currency] || @user.family.currency },
-                                 { data: { action: "onboarding#setCurrency" } } %>
+                                 { label: t(".currency"), required: true, selected: selected_currency },
+                                 { data: { action: "onboarding#setCurrency", onboarding_target: "currencyField" } } %>
 
           <%= family_form.select :date_format,
                                  Family::DATE_FORMATS,
diff --git a/app/views/onboardings/show.html.erb b/app/views/onboardings/show.html.erb
index 38d90b378..e3cf457f5 100644
--- a/app/views/onboardings/show.html.erb
+++ b/app/views/onboardings/show.html.erb
@@ -10,7 +10,12 @@
   <%= render "onboardings/logout" %>
 <% end %>
 
-<div class="grow max-w-lg w-full mx-auto bg-surface flex flex-col justify-center md:py-0 py-2 px-4 md:px-0">
+<div class="grow max-w-lg w-full mx-auto bg-surface flex flex-col justify-center md:py-0 py-2 px-4 md:px-0"
+  data-controller="onboarding"
+  data-onboarding-household-name-label-value="<%= t(".household_name") %>"
+  data-onboarding-household-name-placeholder-value="<%= t(".household_name_placeholder") %>"
+  data-onboarding-group-name-label-value="<%= t(".group_name") %>"
+  data-onboarding-group-name-placeholder-value="<%= t(".group_name_placeholder") %>">
   <div>
     <div class="space-y-1 mb-6 text-center">
       <h1 class="text-2xl font-medium md:text-2xl"><%= t(".title") %></h1>
@@ -34,12 +39,7 @@
         <div class="space-y-4 mb-4">
           <%= form.fields_for :family do |family_form| %>
             <div class="bg-container rounded-lg shadow-border-xs p-4">
-              <div class="space-y-2"
-                data-controller="onboarding"
-                data-onboarding-household-name-label-value="<%= t(".household_name") %>"
-                data-onboarding-household-name-placeholder-value="<%= t(".household_name_placeholder") %>"
-                data-onboarding-group-name-label-value="<%= t(".group_name") %>"
-                data-onboarding-group-name-placeholder-value="<%= t(".group_name_placeholder") %>">
+              <div class="space-y-2">
                 <p class="text-sm font-medium text-primary"><%= t(".moniker_prompt", product_name: product_name) %></p>
 
                 <label class="flex items-center gap-2 text-sm text-primary">
@@ -67,7 +67,7 @@
             <%= family_form.select :country,
                                    country_options,
                                    { label: t(".country") },
-                                   required: true %>
+                                   { required: true, data: { onboarding_target: "countryField" } } %>
           <% end %>
         </div>
       <% end %>
diff --git a/test/controllers/onboardings_controller_test.rb b/test/controllers/onboardings_controller_test.rb
index 2c83854db..d1bfbe4cf 100644
--- a/test/controllers/onboardings_controller_test.rb
+++ b/test/controllers/onboardings_controller_test.rb
@@ -109,6 +109,44 @@ class OnboardingsControllerTest < ActionDispatch::IntegrationTest
     assert_select "span", text: /\+\$78\.90/
   end
 
+  test "preferences page derives currency from the onboarding country" do
+    @family.update!(country: "CA", currency: "USD")
+
+    get preferences_onboarding_url
+
+    assert_response :success
+    assert_select "select[name='user[family_attributes][currency]'] option[selected][value='CAD']"
+  end
+
+  test "preferences page keeps the saved currency after preferences have been set" do
+    @family.update!(country: "CA", currency: "USD")
+    @user.update!(set_onboarding_preferences_at: Time.current)
+
+    get preferences_onboarding_url
+
+    assert_response :success
+    assert_select "select[name='user[family_attributes][currency]'] option[selected][value='USD']"
+  end
+
+  test "preferences page preserves an explicit currency override" do
+    @family.update!(country: "CA", currency: "USD")
+
+    get preferences_onboarding_url, params: { currency: "USD" }
+
+    assert_response :success
+    assert_select "select[name='user[family_attributes][currency]'] option[selected][value='USD']"
+  end
+
+  test "preferences page ignores an unsupported currency override" do
+    @family.update!(country: "CA", currency: "USD")
+
+    get preferences_onboarding_url, params: { currency: "NOPE" }
+
+    assert_response :success
+    assert_select "[data-onboarding-currency-override-value='false']"
+    assert_select "select[name='user[family_attributes][currency]'] option[selected][value='CAD']"
+  end
+
   test "preferences page shows date formatting example" do
   get preferences_onboarding_url
   assert_response :success
diff --git a/test/models/family_test.rb b/test/models/family_test.rb
index b214e5c1e..d84e01759 100644
--- a/test/models/family_test.rb
+++ b/test/models/family_test.rb
@@ -165,6 +165,13 @@ class FamilyTest < ActiveSupport::TestCase
     assert_equal "Groups", family.moniker_label_plural
   end
 
+  test "default currency comes from country ISO data" do
+    assert_equal "CAD", Family.default_currency_for_country("CA")
+    assert_equal "EUR", Family.default_currency_for_country("DE")
+    assert_equal "BRL", Family.default_currency_for_country("BR")
+    assert_equal "USD", Family.default_currency_for_country("unknown")
+  end
+
   test "available_merchants includes family merchants without transactions" do
     family = families(:dylan_family)
 
diff --git a/test/system/onboardings_test.rb b/test/system/onboardings_test.rb
index 19410b53a..76fc3e5f5 100644
--- a/test/system/onboardings_test.rb
+++ b/test/system/onboardings_test.rb
@@ -48,6 +48,38 @@ class OnboardingsTest < ApplicationSystemTestCase
     assert_text I18n.t("onboardings.goals.title")
   end
 
+  test "browser locale defaults onboarding country and currency" do
+    @family.update!(country: "US", currency: "USD")
+    set_browser_language("en-CA")
+
+    visit onboarding_path
+
+    assert_equal "CA", find("#user_family_attributes_country").value
+
+    click_button I18n.t("onboardings.show.submit")
+    assert_current_path preferences_onboarding_path
+
+    assert_equal "CAD", find("#user_family_attributes_currency").value
+
+    click_button I18n.t("onboardings.preferences.submit")
+    assert_current_path goals_onboarding_path
+
+    @family.reload
+    assert_equal "CA", @family.country
+    assert_equal "CAD", @family.currency
+  end
+
+  test "saved currency stays authoritative after onboarding controller connects" do
+    @family.update!(country: "CA", currency: "USD")
+    @user.update!(set_onboarding_preferences_at: Time.current)
+    set_browser_language("en-CA")
+
+    visit preferences_onboarding_path
+
+    assert_selector "[data-onboarding-currency-override-value='true']"
+    assert_equal "USD", find("#user_family_attributes_currency").value
+  end
+
   test "preferences page renders chart without errors" do
     visit preferences_onboarding_path
 
@@ -194,6 +226,18 @@ class OnboardingsTest < ApplicationSystemTestCase
         .select_option
     end
 
+    def set_browser_language(language)
+      page.driver.browser.execute_cdp(
+        "Page.addScriptToEvaluateOnNewDocument",
+        source: <<~JS
+          Object.defineProperty(navigator, "language", {
+            get: () => "#{language}",
+            configurable: true
+          });
+        JS
+      )
+    end
+
     def sign_in(user)
       visit new_session_path
       within %(form[action='#{sessions_path}']) do