diff --git a/Package.resolved b/Package.resolved
index de67425..98debd1 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "b6e6af1076a5bcce49e1231c44be25d770eaef278e2d1ce1c961446d49cb2d00",
+  "originHash" : "9668a267c19bc66e844dc3e46718c4415359171b587f26c2a592bc347bd5446a",
   "pins" : [
     {
       "identity" : "async-http-client",
@@ -172,6 +172,15 @@
         "version" : "1.2.1"
       }
     },
+    {
+      "identity" : "swift-argument-parser",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-argument-parser.git",
+      "state" : {
+        "revision" : "c5d11a805e765f52ba34ec7284bd4fcd6ba68615",
+        "version" : "1.7.0"
+      }
+    },
     {
       "identity" : "swift-asn1",
       "kind" : "remoteSourceControl",
diff --git a/Package.swift b/Package.swift
index 0001219..0c4b14a 100644
--- a/Package.swift
+++ b/Package.swift
@@ -6,6 +6,7 @@ let package = Package(
   name: "swift-manual-d",
   products: [
     .executable(name: "App", targets: ["App"]),
+    .executable(name: "ductcalc", targets: ["CLI"]),
     .library(name: "AuthClient", targets: ["AuthClient"]),
     .library(name: "CSVParser", targets: ["CSVParser"]),
     .library(name: "DatabaseClient", targets: ["DatabaseClient"]),
@@ -20,6 +21,7 @@ let package = Package(
     .library(name: "ViewController", targets: ["ViewController"]),
   ],
   dependencies: [
+    .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.7.0"),
     .package(url: "https://github.com/vapor/vapor.git", from: "4.110.1"),
     .package(url: "https://github.com/vapor/fluent.git", from: "4.9.0"),
     .package(url: "https://github.com/vapor/fluent-sqlite-driver.git", from: "4.6.0"),
@@ -54,6 +56,13 @@ let package = Package(
         .product(name: "VaporRouting", package: "vapor-routing"),
       ]
     ),
+    .executableTarget(
+      name: "CLI",
+      dependencies: [
+        .target(name: "ManualDClient"),
+        .product(name: "ArgumentParser", package: "swift-argument-parser"),
+      ]
+    ),
     .target(
       name: "AuthClient",
       dependencies: [
diff --git a/Sources/CLI/Cli.swift b/Sources/CLI/Cli.swift
new file mode 100644
index 0000000..b716c36
--- /dev/null
+++ b/Sources/CLI/Cli.swift
@@ -0,0 +1,14 @@
+import ArgumentParser
+
+@main
+struct DuctCalcCli: AsyncParsableCommand {
+  static let configuration: CommandConfiguration = .init(
+    commandName: "ductcalc",
+    abstract: "Perform duct calculations.",
+    subcommands: [
+      ConvertCommand.self,
+      SizeCommand.self,
+    ],
+    defaultSubcommand: SizeCommand.self
+  )
+}
diff --git a/Sources/CLI/Commands/Convert.swift b/Sources/CLI/Commands/Convert.swift
new file mode 100644
index 0000000..4f04df0
--- /dev/null
+++ b/Sources/CLI/Commands/Convert.swift
@@ -0,0 +1,35 @@
+import ArgumentParser
+import Dependencies
+import ManualDClient
+
+struct ConvertCommand: AsyncParsableCommand {
+
+  static let configuration = CommandConfiguration(
+    commandName: "convert",
+    abstract: "Convert to an equivalent recangular size."
+  )
+
+  @Option(
+    name: .shortAndLong,
+    help: "The height"
+  )
+  var height: Int
+
+  @Argument(
+    // name: .shortAndLong,
+    help: "The round size."
+  )
+  var roundSize: Int
+
+  func run() async throws {
+    @Dependency(\.manualD) var manualD
+
+    let size = try await manualD.rectangularSize(
+      round: .init(roundSize),
+      height: .init(height)
+    )
+
+    print("\(size.width) x \(height)")
+  }
+
+}
diff --git a/Sources/CLI/Commands/Size.swift b/Sources/CLI/Commands/Size.swift
new file mode 100644
index 0000000..e553c15
--- /dev/null
+++ b/Sources/CLI/Commands/Size.swift
@@ -0,0 +1,35 @@
+import ArgumentParser
+import Dependencies
+import ManualDClient
+
+struct SizeCommand: AsyncParsableCommand {
+  static let configuration = CommandConfiguration(
+    commandName: "size",
+    abstract: "Calculate the required size of a duct."
+  )
+
+  @Option(
+    name: .shortAndLong,
+    help: "The design friction rate."
+  )
+  var frictionRate: Double = 0.06
+
+  @Argument(
+    help: "The required CFM for the duct."
+  )
+  var cfm: Int
+
+  func run() async throws {
+    @Dependency(\.manualD) var manualD
+
+    let size = try await manualD.ductSize(cfm: cfm, frictionRate: frictionRate)
+    print(
+      """
+      Calculated: \(size.calculatedSize.string(digits: 2))
+      Final Size: \(size.finalSize)
+      Flex Size: \(size.flexSize)
+      """
+    )
+
+  }
+}
diff --git a/Tests/DatabaseClientTests/Resources/rooms.csv b/Tests/DatabaseClientTests/Resources/rooms.csv
index 5f7eb3e..cf9b958 100644
--- a/Tests/DatabaseClientTests/Resources/rooms.csv
+++ b/Tests/DatabaseClientTests/Resources/rooms.csv
@@ -1,4 +1,3 @@
-
 Name,Heating Load,Cooling Total,Cooling Sensible,Register Count,Delegated To
 Bed-1,12345,1234,1321,1,
 Entry,3456,2345,1234,1,