diff --git a/lib/ai/formula_screen.dart b/lib/ai/formula_screen.dart
new file mode 100644
index 0000000..502af7e
--- /dev/null
+++ b/lib/ai/formula_screen.dart
@@ -0,0 +1,227 @@
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import '../formula_models.dart';
+import '../formula_evaluator.dart';
+import '../corpus.dart';
+import 'unit_dropdown.dart';
+
+class FormulaScreen extends StatefulWidget {
+  final Formula formula;
+  final UnitCorpus corpus;
+
+  const FormulaScreen({
+    super.key,
+    required this.formula,
+    required this.corpus,
+  });
+
+  @override
+  State<FormulaScreen> createState() => _FormulaScreenState();
+}
+
+class _FormulaScreenState extends State<FormulaScreen> {
+  final _formKey = GlobalKey<FormState>();
+  final Map<String, TextEditingController> _inputControllers = {};
+  final Map<String, String?> _selectedUnits = {};
+  String? _result;
+  String? _selectedOutputUnit;
+
+  @override
+  void initState() {
+    super.initState();
+    // Initialize controllers and units
+    for (final input in widget.formula.input) {
+      _inputControllers[input.name] = TextEditingController();
+      _selectedUnits[input.name] = input.magnitude;
+    }
+    _selectedOutputUnit = widget.formula.output.magnitude;
+  }
+
+  @override
+  void dispose() {
+    // Clean up controllers
+    for (final controller in _inputControllers.values) {
+      controller.dispose();
+    }
+    super.dispose();
+  }
+
+  void _evaluateFormula() {
+    if (!_formKey.currentState!.validate()) return;
+
+    try {
+      final inputValues = <String, dynamic>{};
+      for (final input in widget.formula.input) {
+        final value = double.tryParse(_inputControllers[input.name]!.text) ?? 0.0;
+
+        // Convert input to base unit if needed
+        if (_selectedUnits[input.name] != input.magnitude) {
+          inputValues[input.name] = widget.corpus.convert(
+            value,
+            _selectedUnits[input.name]!,
+            input.magnitude,
+          );
+        } else {
+          inputValues[input.name] = value;
+        }
+      }
+
+      final evaluator = FormulaEvaluator();
+      final result = evaluator.evaluate(widget.formula, inputValues);
+
+      // Convert output to selected unit if needed
+      if (_selectedOutputUnit != widget.formula.output.magnitude) {
+        _result = widget.corpus.convert(
+          result,
+          widget.formula.output.magnitude,
+          _selectedOutputUnit!,
+        ).toStringAsFixed(2);
+      } else {
+        _result = result.toStringAsFixed(2);
+      }
+
+      setState(() {});
+    } catch (e) {
+      e
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text('Evaluation error: ${e.toString()}'),
+          backgroundColor: Theme.of(context).colorScheme.error,
+        ),
+      );
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.formula.name),
+      ),
+      body: Form(
+        key: _formKey,
+        child: Padding(
+          padding: const EdgeInsets.all(16.0),
+          child: Column(
+            children: [
+              Expanded(
+                child: ListView(
+                  children: [
+                    _buildInputSection(),
+                    const SizedBox(height: 24),
+                    _buildOutputSection(),
+                  ],
+                ),
+              ),
+              ElevatedButton(
+                onPressed: _evaluateFormula,
+                child: const Text('Calculate'),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildInputSection() {
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Text(
+          'Input Variables',
+          style: Theme.of(context).textTheme.titleMedium?.copyWith(
+            fontWeight: FontWeight.bold,
+          ),
+        ),
+        const SizedBox(height: 8),
+        ...widget.formula.input.map((variable) => _buildVariableRow(variable)),
+      ],
+    );
+  }
+
+  Widget _buildOutputSection() {
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Text(
+          'Result',
+          style: Theme.of(context).textTheme.titleMedium?.copyWith(
+            fontWeight: FontWeight.bold,
+          ),
+        ),
+        const SizedBox(height: 8),
+        Row(
+          children: [
+            Text(widget.formula.output.name),
+            const Spacer(),
+            SizedBox(
+              width: 100,
+              child: TextFormField(
+                readOnly: true,
+                controller: TextEditingController(text: _result),
+                decoration: const InputDecoration(
+                  border: UnderlineInputBorder(),
+                ),
+              ),
+            ),
+            const SizedBox(width: 8),
+            UnitDropdown(
+              corpus: widget.corpus,
+              variable: widget.formula.output,
+              selectedUnit: _selectedOutputUnit,
+              onUnitChanged: (unit) {
+                setState(() {
+                  _selectedOutputUnit = unit;
+                });
+              },
+            ),
+          ],
+        ),
+      ],
+    );
+  }
+
+  Widget _buildVariableRow(VariableSpec variable) {
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: 8.0),
+      child: Row(
+        children: [
+          Text(variable.name),
+          const Spacer(),
+          SizedBox(
+            width: 100,
+            child: TextFormField(
+              controller: _inputControllers[variable.name],
+              keyboardType: TextInputType.number,
+              inputFormatters: [
+                FilteringTextInputFormatter.allow(RegExp(r'[0-9\.\-]')),
+              ],
+              decoration: const InputDecoration(
+                border: UnderlineInputBorder(),
+              ),
+              validator: (value) {
+                if (value == null || value.isEmpty) {
+                  return 'Required';
+                }
+                return null;
+              },
+            ),
+          ),
+          const SizedBox(width: 8),
+          UnitDropdown(
+            corpus: widget.corpus,
+            variable: variable,
+            selectedUnit: _selectedUnits[variable.name],
+            onUnitChanged: (unit) {
+              setState(() {
+                _selectedUnits[variable.name] = unit;
+              });
+            },
+          ),
+        ],
+      ),
+    );
+  }
+}
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