diff --git a/static/js/weekendsLeft.js b/static/js/weekendsLeft.js
index 2d335a1..2bc7361 100644
--- a/static/js/weekendsLeft.js
+++ b/static/js/weekendsLeft.js
@@ -3,7 +3,7 @@
 
     var form = document.getElementById('weekends-form');
     var birthYearInput = document.getElementById('birth-year');
-    var deathYearInput = document.getElementById('death-year');
+    var deathAgeInput = document.getElementById('death-age');
     var resultsDiv = document.getElementById('weekends-results');
     var percentageRemainingEl = document.getElementById('percentage-remaining');
     var usedCountEl = document.getElementById('used-count');
@@ -200,18 +200,20 @@
 
     function calculate() {
         var birthYear = parseInt(birthYearInput.value, 10);
-        var deathYear = parseInt(deathYearInput.value, 10);
+        var deathAge = parseInt(deathAgeInput.value, 10);
 
-        if (!birthYear || !deathYear) {
+        if (!birthYear || !deathAge) {
             resultsDiv.style.display = 'none';
             return;
         }
 
-        if (deathYear <= birthYear) {
+        if (deathAge < 1 || deathAge > 999) {
             resultsDiv.style.display = 'none';
             return;
         }
 
+        var deathYear = birthYear + deathAge;
+
         var birthDate = new Date(birthYear, 0, 1);
         var deathDate = new Date(deathYear, 11, 31);
         var today = new Date();
@@ -246,7 +248,7 @@
     }
 
     birthYearInput.addEventListener('input', calculate);
-    deathYearInput.addEventListener('input', calculate);
+    deathAgeInput.addEventListener('input', calculate);
     form.addEventListener('submit', function(e) {
         e.preventDefault();
         calculate();
diff --git a/templates/shortcodes/weekends_left.html b/templates/shortcodes/weekends_left.html
index 6962aea..e61a9ef 100644
--- a/templates/shortcodes/weekends_left.html
+++ b/templates/shortcodes/weekends_left.html
@@ -6,8 +6,8 @@
                 <input type="number" id="birth-year" min="1900" max="2100" placeholder="1998">
             </div>
             <div class="form-group">
-                <label for="death-year">Death year:</label>
-                <input type="number" id="death-year" min="1900" max="2200" placeholder="2088">
+                <label for="death-age">Age at death:</label>
+                <input type="number" id="death-age" min="1" max="999" placeholder="90">
             </div>
         </div>
     </form>