diff --git a/dog-food-calculator-widget.js b/dog-food-calculator-widget.js
index 839442d..be368cf 100644
--- a/dog-food-calculator-widget.js
+++ b/dog-food-calculator-widget.js
@@ -978,10 +978,21 @@
                 </div>
                 <div class="dog-calc-collapsible-content">
                     <div class="dog-calc-collapsible-inner">
-                        <div class="dog-calc-form-group">
-                            <label for="foodEnergy" id="foodEnergyLabel">Food Energy Content (kcal/100g):</label>
-                            <input type="number" id="foodEnergy" min="1" step="1" placeholder="Enter kcal per 100g" aria-describedby="foodEnergyHelp">
-                            <div id="foodEnergyError" class="dog-calc-error dog-calc-hidden">Please enter a valid energy content (minimum 1 kcal/100g)</div>
+                        <div class="dog-calc-input-group">
+                            <div class="dog-calc-form-group">
+                                <label for="foodEnergy" id="foodEnergyLabel">Food Energy Content:</label>
+                                <input type="number" id="foodEnergy" min="1" step="1" placeholder="Enter energy content" aria-describedby="foodEnergyHelp">
+                                <div id="foodEnergyError" class="dog-calc-error dog-calc-hidden">Please enter a valid energy content</div>
+                            </div>
+                            <div class="dog-calc-form-group">
+                                <label for="energyUnit">Unit:</label>
+                                <select id="energyUnit" class="dog-calc-unit-select" aria-describedby="energyUnitHelp">
+                                    <option value="kcal100g">kcal/100g</option>
+                                    <option value="kcalkg">kcal/kg</option>
+                                    <option value="kcalcup">kcal/cup</option>
+                                    <option value="kcalcan">kcal/can</option>
+                                </select>
+                            </div>
                         </div>
 
                         <div class="dog-calc-results" id="dailyFoodResults" style="display: none;">
@@ -1188,6 +1199,9 @@
                 foodEnergyInput.addEventListener('input', () => this.updateFoodCalculations());
                 foodEnergyInput.addEventListener('blur', () => this.validateFoodEnergy());
             }
+
+            const energyUnitSelect = this.container.querySelector('#energyUnit');
+            if (energyUnitSelect) energyUnitSelect.addEventListener('change', () => this.updateFoodCalculations());
             
             if (daysInput) {
                 daysInput.addEventListener('input', () => this.updateFoodCalculations());
@@ -1264,9 +1278,7 @@
             const metricLabel = this.container.querySelector('#metricLabel');
             const imperialLabel = this.container.querySelector('#imperialLabel');
             const weightLabel = this.container.querySelector('#weightLabel');
-            const foodEnergyLabel = this.container.querySelector('#foodEnergyLabel');
             const weightInput = this.container.querySelector('#weight');
-            const foodEnergyInput = this.container.querySelector('#foodEnergy');
             const unitSelect = this.container.querySelector('#unit');
 
             if (metricLabel && imperialLabel) {
@@ -1281,12 +1293,6 @@
                     weightInput.min = "0.2";
                     weightInput.step = "0.1";
                 }
-                if (foodEnergyLabel) foodEnergyLabel.textContent = "Food Energy Content (kcal/oz):";
-                if (foodEnergyInput) {
-                    foodEnergyInput.placeholder = "Enter kcal per oz";
-                    foodEnergyInput.min = "0.03";
-                    foodEnergyInput.step = "0.01";
-                }
                 if (unitSelect) {
                     unitSelect.innerHTML = `
                         <option value="oz">ounces (oz)</option>
@@ -1302,12 +1308,6 @@
                     weightInput.min = "0.1";
                     weightInput.step = "0.1";
                 }
-                if (foodEnergyLabel) foodEnergyLabel.textContent = "Food Energy Content (kcal/100g):";
-                if (foodEnergyInput) {
-                    foodEnergyInput.placeholder = "Enter kcal per 100g";
-                    foodEnergyInput.min = "1";
-                    foodEnergyInput.step = "1";
-                }
                 if (unitSelect) {
                     unitSelect.innerHTML = `
                         <option value="g">grams (g)</option>
@@ -1321,7 +1321,6 @@
 
         convertExistingValues() {
             const weightInput = this.container.querySelector('#weight');
-            const foodEnergyInput = this.container.querySelector('#foodEnergy');
 
             if (weightInput && weightInput.value) {
                 const currentWeight = parseFloat(weightInput.value);
@@ -1333,17 +1332,6 @@
                     }
                 }
             }
-
-            if (foodEnergyInput && foodEnergyInput.value) {
-                const currentEnergy = parseFloat(foodEnergyInput.value);
-                if (!isNaN(currentEnergy)) {
-                    if (this.isImperial) {
-                        foodEnergyInput.value = this.formatNumber(currentEnergy / 3.52739, 2);
-                    } else {
-                        foodEnergyInput.value = this.formatNumber(currentEnergy * 3.52739, 0);
-                    }
-                }
-            }
         }
 
         getWeightInKg() {
@@ -1358,12 +1346,27 @@
 
         getFoodEnergyPer100g() {
             const foodEnergyInput = this.container.querySelector('#foodEnergy');
-            if (!foodEnergyInput || !foodEnergyInput.value) return null;
+            const energyUnitSelect = this.container.querySelector('#energyUnit');
+            if (!foodEnergyInput || !foodEnergyInput.value || !energyUnitSelect) return null;
             
             const energy = parseFloat(foodEnergyInput.value);
             if (isNaN(energy)) return null;
             
-            return this.isImperial ? energy * 3.52739 : energy;
+            const unit = energyUnitSelect.value;
+            
+            // Convert all units to kcal/100g for internal calculations
+            switch (unit) {
+                case 'kcal100g':
+                    return energy;
+                case 'kcalkg':
+                    return energy / 10; // 1 kg = 10 × 100g
+                case 'kcalcup':
+                    return energy / 1.2; // Assume 1 cup ≈ 120g for dry dog food
+                case 'kcalcan':
+                    return energy / 4.5; // Assume 1 can ≈ 450g for wet dog food
+                default:
+                    return energy;
+            }
         }
 
         calculateRER(weightKg) {
@@ -1418,8 +1421,34 @@
         }
 
         validateFoodEnergy() {
-            const energy = this.container.querySelector('#foodEnergy')?.value;
-            if (energy && !this.validateInput(energy, 1)) {
+            const energyInput = this.container.querySelector('#foodEnergy');
+            const energyUnitSelect = this.container.querySelector('#energyUnit');
+            
+            if (!energyInput || !energyInput.value) {
+                this.showError('foodEnergyError', false);
+                return;
+            }
+            
+            const energy = parseFloat(energyInput.value);
+            const unit = energyUnitSelect?.value || 'kcal100g';
+            
+            let minValue = 1;
+            switch (unit) {
+                case 'kcal100g':
+                    minValue = 1;
+                    break;
+                case 'kcalkg':
+                    minValue = 10;
+                    break;
+                case 'kcalcup':
+                    minValue = 50;
+                    break;
+                case 'kcalcan':
+                    minValue = 100;
+                    break;
+            }
+            
+            if (!this.validateInput(energy, minValue)) {
                 this.showError('foodEnergyError', true);
             } else {
                 this.showError('foodEnergyError', false);
@@ -1496,7 +1525,7 @@
             this.showError('foodEnergyError', false);
             this.showError('daysError', false);
             
-            if (!energyPer100g || energyPer100g < 1) {
+            if (!energyPer100g || energyPer100g < 0.1) {
                 const foodEnergyInput = this.container.querySelector('#foodEnergy');
                 if (foodEnergyInput && foodEnergyInput.value) this.showError('foodEnergyError', true);
                 dailyFoodResults.style.display = 'none';
diff --git a/iframe.html b/iframe.html
index f4ff04a..abb1b43 100644
--- a/iframe.html
+++ b/iframe.html
@@ -958,10 +958,21 @@
             </div>
             <div class="dog-calculator-collapsible-content">
                 <div class="dog-calculator-collapsible-inner">
-                    <div class="dog-calculator-form-group">
-                        <label for="foodEnergy" id="foodEnergyLabel">Food Energy Content (kcal/100g):</label>
-                        <input type="number" id="foodEnergy" min="1" step="1" placeholder="Enter kcal per 100g" aria-describedby="foodEnergyHelp">
-                        <div id="foodEnergyError" class="dog-calculator-error dog-calculator-hidden">Please enter a valid energy content (minimum 1 kcal/100g)</div>
+                    <div class="dog-calculator-input-group">
+                        <div class="dog-calculator-form-group">
+                            <label for="foodEnergy" id="foodEnergyLabel">Food Energy Content:</label>
+                            <input type="number" id="foodEnergy" min="1" step="1" placeholder="Enter energy content" aria-describedby="foodEnergyHelp">
+                            <div id="foodEnergyError" class="dog-calculator-error dog-calculator-hidden">Please enter a valid energy content</div>
+                        </div>
+                        <div class="dog-calculator-form-group">
+                            <label for="energyUnit">Unit:</label>
+                            <select id="energyUnit" class="dog-calculator-unit-select" aria-describedby="energyUnitHelp">
+                                <option value="kcal100g">kcal/100g</option>
+                                <option value="kcalkg">kcal/kg</option>
+                                <option value="kcalcup">kcal/cup</option>
+                                <option value="kcalcan">kcal/can</option>
+                            </select>
+                        </div>
                     </div>
 
                     <div class="dog-calculator-results" id="dailyFoodResults" style="display: none;">
@@ -1126,6 +1137,9 @@
                     foodEnergyInput.addEventListener('input', () => this.updateFoodCalculations());
                     foodEnergyInput.addEventListener('blur', () => this.validateFoodEnergy());
                 }
+
+                const energyUnitSelect = document.getElementById('energyUnit');
+                if (energyUnitSelect) energyUnitSelect.addEventListener('change', () => this.updateFoodCalculations());
                 
                 if (daysInput) {
                     daysInput.addEventListener('input', () => this.updateFoodCalculations());
@@ -1197,9 +1211,7 @@
                 const metricLabel = document.getElementById('metricLabel');
                 const imperialLabel = document.getElementById('imperialLabel');
                 const weightLabel = document.getElementById('weightLabel');
-                const foodEnergyLabel = document.getElementById('foodEnergyLabel');
                 const weightInput = document.getElementById('weight');
-                const foodEnergyInput = document.getElementById('foodEnergy');
                 const unitSelect = document.getElementById('unit');
 
                 if (metricLabel && imperialLabel) {
@@ -1214,12 +1226,6 @@
                         weightInput.min = "0.2";
                         weightInput.step = "0.1";
                     }
-                    if (foodEnergyLabel) foodEnergyLabel.textContent = "Food Energy Content (kcal/oz):";
-                    if (foodEnergyInput) {
-                        foodEnergyInput.placeholder = "Enter kcal per oz";
-                        foodEnergyInput.min = "0.03";
-                        foodEnergyInput.step = "0.01";
-                    }
                     if (unitSelect) {
                         unitSelect.innerHTML = '<option value="oz">ounces (oz)</option>' +
                             '<option value="lb">pounds (lb)</option>' +
@@ -1233,12 +1239,6 @@
                         weightInput.min = "0.1";
                         weightInput.step = "0.1";
                     }
-                    if (foodEnergyLabel) foodEnergyLabel.textContent = "Food Energy Content (kcal/100g):";
-                    if (foodEnergyInput) {
-                        foodEnergyInput.placeholder = "Enter kcal per 100g";
-                        foodEnergyInput.min = "1";
-                        foodEnergyInput.step = "1";
-                    }
                     if (unitSelect) {
                         unitSelect.innerHTML = '<option value="g">grams (g)</option>' +
                             '<option value="kg">kilograms (kg)</option>' +
@@ -1250,7 +1250,6 @@
 
             convertExistingValues() {
                 const weightInput = document.getElementById('weight');
-                const foodEnergyInput = document.getElementById('foodEnergy');
 
                 if (weightInput && weightInput.value) {
                     const currentWeight = parseFloat(weightInput.value);
@@ -1262,17 +1261,6 @@
                         }
                     }
                 }
-
-                if (foodEnergyInput && foodEnergyInput.value) {
-                    const currentEnergy = parseFloat(foodEnergyInput.value);
-                    if (!isNaN(currentEnergy)) {
-                        if (this.isImperial) {
-                            foodEnergyInput.value = this.formatNumber(currentEnergy / 3.52739, 2);
-                        } else {
-                            foodEnergyInput.value = this.formatNumber(currentEnergy * 3.52739, 0);
-                        }
-                    }
-                }
             }
 
             getWeightInKg() {
@@ -1287,12 +1275,27 @@
 
             getFoodEnergyPer100g() {
                 const foodEnergyInput = document.getElementById('foodEnergy');
-                if (!foodEnergyInput || !foodEnergyInput.value) return null;
+                const energyUnitSelect = document.getElementById('energyUnit');
+                if (!foodEnergyInput || !foodEnergyInput.value || !energyUnitSelect) return null;
                 
                 const energy = parseFloat(foodEnergyInput.value);
                 if (isNaN(energy)) return null;
                 
-                return this.isImperial ? energy * 3.52739 : energy;
+                const unit = energyUnitSelect.value;
+                
+                // Convert all units to kcal/100g for internal calculations
+                switch (unit) {
+                    case 'kcal100g':
+                        return energy;
+                    case 'kcalkg':
+                        return energy / 10; // 1 kg = 10 × 100g
+                    case 'kcalcup':
+                        return energy / 1.2; // Assume 1 cup ≈ 120g for dry dog food
+                    case 'kcalcan':
+                        return energy / 4.5; // Assume 1 can ≈ 450g for wet dog food
+                    default:
+                        return energy;
+                }
             }
 
             calculateRER(weightKg) {
@@ -1351,8 +1354,34 @@
             }
 
             validateFoodEnergy() {
-                const energyPer100g = this.getFoodEnergyPer100g();
-                if (energyPer100g !== null && energyPer100g < 1) {
+                const energyInput = document.getElementById('foodEnergy');
+                const energyUnitSelect = document.getElementById('energyUnit');
+                
+                if (!energyInput || !energyInput.value) {
+                    this.showError('foodEnergyError', false);
+                    return;
+                }
+                
+                const energy = parseFloat(energyInput.value);
+                const unit = energyUnitSelect?.value || 'kcal100g';
+                
+                let minValue = 1;
+                switch (unit) {
+                    case 'kcal100g':
+                        minValue = 1;
+                        break;
+                    case 'kcalkg':
+                        minValue = 10;
+                        break;
+                    case 'kcalcup':
+                        minValue = 50;
+                        break;
+                    case 'kcalcan':
+                        minValue = 100;
+                        break;
+                }
+                
+                if (!this.validateInput(energy, minValue)) {
                     this.showError('foodEnergyError', true);
                 } else {
                     this.showError('foodEnergyError', false);
@@ -1430,7 +1459,7 @@
                 this.showError('foodEnergyError', false);
                 this.showError('daysError', false);
                 
-                if (!energyPer100g || energyPer100g < 1) {
+                if (!energyPer100g || energyPer100g < 0.1) {
                     const foodEnergyInput = document.getElementById('foodEnergy');
                     if (foodEnergyInput && foodEnergyInput.value) this.showError('foodEnergyError', true);
                     dailyFoodResults.style.display = 'none';