diff --git a/public/js/calculators.js b/public/js/calculators.js
index 905c084..64e839d 100644
--- a/public/js/calculators.js
+++ b/public/js/calculators.js
@@ -1151,11 +1151,21 @@
         return;
       }
 
-      var yr = parseFloat((document.getElementById('growth-age-yr') || {}).value) || 0;
-      var mo = parseFloat((document.getElementById('growth-age-mo') || {}).value) || 0;
-      var dy = parseFloat((document.getElementById('growth-age-d') || {}).value) || 0;
+      var yrEl = document.getElementById('growth-age-yr');
+      var moEl = document.getElementById('growth-age-mo');
+      var dyEl = document.getElementById('growth-age-d');
+      var yrRaw = yrEl ? yrEl.value.trim() : '';
+      var moRaw = moEl ? moEl.value.trim() : '';
+      var dyRaw = dyEl ? dyEl.value.trim() : '';
+      // Treat blank fields as 0, but require at least ONE field to have any value.
+      // "0 days" (newborn at birth) is valid — explicit zero counts.
+      if (yrRaw === '' && moRaw === '' && dyRaw === '') {
+        showToast('Enter age (years, months, or days)', 'error'); return;
+      }
+      var yr = parseFloat(yrRaw) || 0;
+      var mo = parseFloat(moRaw) || 0;
+      var dy = parseFloat(dyRaw) || 0;
       var age = yr * 12 + mo + dy / 30.4375; // age in months, fractional OK
-      if (!age && yr === 0 && mo === 0 && dy === 0) { showToast('Enter age (years, months, or days)', 'error'); return; }
       if (age < 0) { showToast('Age cannot be negative', 'error'); return; }
 
       if (currentGrowthType === 'wfa') {
@@ -1266,11 +1276,11 @@
     var ageHint = document.getElementById('growth-age-parsed');
     function updateAgeHint() {
       if (!ageHint) return;
-      var yr = parseFloat((document.getElementById('growth-age-yr') || {}).value) || 0;
-      var mo = parseFloat((document.getElementById('growth-age-mo') || {}).value) || 0;
-      var dy = parseFloat((document.getElementById('growth-age-d') || {}).value) || 0;
-      if (!yr && !mo && !dy) { ageHint.textContent = ''; return; }
-      var total = yr * 12 + mo + dy / 30.4375;
+      var yrRaw = ((document.getElementById('growth-age-yr') || {}).value || '').trim();
+      var moRaw = ((document.getElementById('growth-age-mo') || {}).value || '').trim();
+      var dyRaw = ((document.getElementById('growth-age-d') || {}).value || '').trim();
+      if (yrRaw === '' && moRaw === '' && dyRaw === '') { ageHint.textContent = ''; return; }
+      var total = (parseFloat(yrRaw) || 0) * 12 + (parseFloat(moRaw) || 0) + (parseFloat(dyRaw) || 0) / 30.4375;
       ageHint.style.color = 'var(--g500)';
       ageHint.textContent = formatParsedAge(total);
     }