diff --git a/hdyc-svelte/src/app.css b/hdyc-svelte/src/app.css
index 953c7e1..db298b9 100644
--- a/hdyc-svelte/src/app.css
+++ b/hdyc-svelte/src/app.css
@@ -669,9 +669,27 @@ a:focus-visible {
 
 .calc-list {
   display: grid;
-  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
+  grid-template-columns: repeat(1, minmax(0, 1fr));
   gap: 0.75rem;
 }
+
+@media (min-width: 640px) {
+  .calc-list {
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+  }
+}
+
+@media (min-width: 960px) {
+  .calc-list {
+    grid-template-columns: repeat(3, minmax(0, 1fr));
+  }
+}
+
+@media (min-width: 1280px) {
+  .calc-list {
+    grid-template-columns: repeat(4, minmax(0, 1fr));
+  }
+}
 .calc-list-item {
   display: block;
   position: relative;
diff --git a/hdyc-svelte/src/lib/data/calculators.ts b/hdyc-svelte/src/lib/data/calculators.ts
index 36b6077..edddcbb 100644
--- a/hdyc-svelte/src/lib/data/calculators.ts
+++ b/hdyc-svelte/src/lib/data/calculators.ts
@@ -379,7 +379,7 @@ export const calculators: CalculatorDef[] = [
   {"slug": "webers-per-square-centimeter-to-gauss", "name": "Webers per square centimeter to Gauss", "category": "magnetism", "type": "standard", "teaser": "Scale the small-area flux into Gauss.", "labels": {"in1": "Webers per square centimeter", "in2": "Gauss"}, "factor": 100000000.0},
   {"slug": "gauss-to-webers-per-square-centimeter", "name": "Gauss to Webers per square centimeter", "category": "magnetism", "type": "standard", "teaser": "Convert Gauss back into Weber per square centimeter.", "labels": {"in1": "Gauss", "in2": "Webers per square centimeter"}, "factor": 1e-08, "hidden": true},
   {"slug": "oersted-to-gauss", "name": "Oersted to Gauss", "category": "magnetism", "type": "standard", "teaser": "In vacuum, the numeric values for Oersted and Gauss match.", "labels": {"in1": "Oersted", "in2": "Gauss"}, "hidden": true},
-  {"slug": "gauss-to-oersted", "name": "Gauss to Oersted", "category": "magnetism", "type": "standard", "teaser": "Translate the flux density version back into the magnetizing force scale.", "labels": {"in1": "Gauss", "in2": "Oersted"}},
+  {"slug": "gauss-to-oersted", "name": "Gauss to Oersted", "category": "magnetism", "type": "standard", "teaser": "Translate the flux density version back into the magnetizing force scale.", "labels": {"in1": "Gauss", "in2": "Oersted"}, "factor": 1.0},
   {"slug": "kilogauss-to-microtesla", "name": "Kilogauss to Microtesla", "category": "magnetism", "type": "standard", "teaser": "A kilogauss field equals 100,000 microtesla.", "labels": {"in1": "Kilogauss", "in2": "Microtesla"}, "factor": 100000.0},
   {"slug": "microtesla-to-kilogauss", "name": "Microtesla to Kilogauss", "category": "magnetism", "type": "standard", "teaser": "Convert microtesla readings into kilogauss.", "labels": {"in1": "Microtesla", "in2": "Kilogauss"}, "factor": 1e-05, "hidden": true},
   {"slug": "kilogauss-to-nanotesla", "name": "Kilogauss to Nanotesla", "category": "magnetism", "type": "standard", "teaser": "Express kilogauss values in nanotesla for sensitive instrumentation.", "labels": {"in1": "Kilogauss", "in2": "Nanotesla"}, "factor": 100000000.0},
diff --git a/tests/test_gauss_to_oersted_conversion_rate.py b/tests/test_gauss_to_oersted_conversion_rate.py
new file mode 100644
index 0000000..68f0dec
--- /dev/null
+++ b/tests/test_gauss_to_oersted_conversion_rate.py
@@ -0,0 +1,43 @@
+import re
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+CALCULATORS_TS = ROOT / "hdyc-svelte" / "src" / "lib" / "data" / "calculators.ts"
+CONVERSION_RATE_UTIL = ROOT / "hdyc-svelte" / "src" / "lib" / "utils" / "conversionRate.ts"
+CATEGORY_PAGE = ROOT / "hdyc-svelte" / "src" / "routes" / "category" / "[category]" / "+page.svelte"
+CALCULATOR_COMPONENT = ROOT / "hdyc-svelte" / "src" / "lib" / "components" / "Calculator.svelte"
+TARGET_SLUG = "gauss-to-oersted"
+
+
+def _extract_calculator_block(slug: str) -> str:
+    for line in CALCULATORS_TS.read_text(encoding="utf-8").splitlines():
+        if f'"slug": "{slug}"' in line:
+            return line
+    raise AssertionError(f"Could not find calculator definition for '{slug}'")
+
+
+class GaussToOerstedConversionRateRegressionTests(unittest.TestCase):
+    def test_gauss_to_oersted_includes_factor_for_conversion_rate_and_tooltip(self) -> None:
+        block = _extract_calculator_block(TARGET_SLUG)
+        self.assertRegex(
+            block,
+            r'"factor":\s*[0-9.eE+-]+',
+            "Missing factor on gauss-to-oersted prevents conversion rate text from rendering in both calculator footer and category tooltip.",
+        )
+
+    def test_conversion_rate_is_wired_to_both_surfaces(self) -> None:
+        util_text = CONVERSION_RATE_UTIL.read_text(encoding="utf-8")
+        category_page_text = CATEGORY_PAGE.read_text(encoding="utf-8")
+        calculator_component_text = CALCULATOR_COMPONENT.read_text(encoding="utf-8")
+
+        self.assertIn("getConversionRateText", util_text)
+        self.assertIn("conversionRateText = getConversionRateText(calc)", category_page_text)
+        self.assertIn('role="tooltip"', category_page_text)
+        self.assertIn("conversionRateText = getConversionRateText(config)", calculator_component_text)
+        self.assertIn('<span class="formula-hint">', calculator_component_text)
+
+
+if __name__ == "__main__":
+    unittest.main()