diff --git a/Package.swift b/Package.swift
index 549d483..9c49dbf 100644
--- a/Package.swift
+++ b/Package.swift
@@ -29,7 +29,10 @@ let package = Package(
     ),
     .testTarget(
       name: "ManualDClientTests",
-      dependencies: ["ManualDClient"]
+      dependencies: [
+        "ManualDClient",
+        .product(name: "DependenciesTestSupport", package: "swift-dependencies"),
+      ]
     ),
     .testTarget(
       name: "swift-manual-dTests",
diff --git a/Sources/ManualDClient/Helpers.swift b/Sources/ManualDClient/Helpers.swift
index 0cacd78..51f1c7d 100644
--- a/Sources/ManualDClient/Helpers.swift
+++ b/Sources/ManualDClient/Helpers.swift
@@ -4,3 +4,9 @@ import ManualDCore
 extension ComponentPressureLosses {
   var totalLosses: Double { values.reduce(0) { $0 + $1 } }
 }
+
+extension Array where Element == EffectiveLengthGroup {
+  var totalEffectiveLength: Int {
+    reduce(0) { $0 + $1.effectiveLength }
+  }
+}
diff --git a/Sources/ManualDClient/Live.swift b/Sources/ManualDClient/Live.swift
index c070bd0..81c089a 100644
--- a/Sources/ManualDClient/Live.swift
+++ b/Sources/ManualDClient/Live.swift
@@ -1,4 +1,5 @@
 import Dependencies
+import Foundation
 import ManualDCore
 
 extension ManualDClient: DependencyKey {
@@ -13,6 +14,31 @@ extension ManualDClient: DependencyKey {
       let availableStaticPressure = request.externalStaticPressure - totalComponentLosses
       let frictionRate = availableStaticPressure * 100.0 / Double(request.totalEffectiveLength)
       return .init(availableStaticPressure: availableStaticPressure, frictionRate: frictionRate)
+    },
+    totalEffectiveLength: { request in
+      let trunkLengths = request.trunkLengths.reduce(0) { $0 + $1 }
+      let runoutLengths = request.runoutLengths.reduce(0) { $0 + $1 }
+      let groupLengths = request.effectiveLengthGroups.totalEffectiveLength
+      return trunkLengths + runoutLengths + groupLengths
+    },
+    equivalentRectangularDuct: { request in
+      let width = (Double.pi * (pow(Double(request.roundSize) / 2.0, 2.0))) / Double(request.height)
+      guard let widthStr = numberFormatter.string(for: width),
+        let widthInt = Int(widthStr)
+      else {
+        throw ManualDError(
+          message: "Failed to convert to to rectangular duct size, width: \(width)"
+        )
+      }
+      return .init(height: request.height, width: widthInt)
     }
   )
 }
+
+private let numberFormatter: NumberFormatter = {
+  let formatter = NumberFormatter()
+  formatter.maximumFractionDigits = 0
+  formatter.minimumFractionDigits = 0
+  formatter.roundingMode = .ceiling
+  return formatter
+}()
diff --git a/Sources/ManualDClient/ManualDClient.swift b/Sources/ManualDClient/ManualDClient.swift
index 3c6ddf3..3ec5106 100644
--- a/Sources/ManualDClient/ManualDClient.swift
+++ b/Sources/ManualDClient/ManualDClient.swift
@@ -5,6 +5,9 @@ import ManualDCore
 @DependencyClient
 public struct ManualDClient: Sendable {
   public var frictionRate: @Sendable (FrictionRateRequest) async throws -> FrictionRateResponse
+  public var totalEffectiveLength: @Sendable (TotalEffectiveLengthRequest) async throws -> Int
+  public var equivalentRectangularDuct:
+    @Sendable (EquivalentRectangularDuctRequest) async throws -> EquivalentRectangularDuctResponse
 }
 
 extension ManualDClient: TestDependencyKey {
@@ -48,3 +51,46 @@ extension ManualDClient {
     }
   }
 }
+
+// MARK: Total Effective Length
+extension ManualDClient {
+  public struct TotalEffectiveLengthRequest: Codable, Equatable, Sendable {
+
+    public let trunkLengths: [Int]
+    public let runoutLengths: [Int]
+    public let effectiveLengthGroups: [EffectiveLengthGroup]
+
+    public init(
+      trunkLengths: [Int],
+      runoutLengths: [Int],
+      effectiveLengthGroups: [EffectiveLengthGroup]
+    ) {
+      self.trunkLengths = trunkLengths
+      self.runoutLengths = runoutLengths
+      self.effectiveLengthGroups = effectiveLengthGroups
+    }
+  }
+}
+
+// MARK: Equivalent Rectangular Duct
+extension ManualDClient {
+  public struct EquivalentRectangularDuctRequest: Codable, Equatable, Sendable {
+    public let roundSize: Int
+    public let height: Int
+
+    public init(round roundSize: Int, height: Int) {
+      self.roundSize = roundSize
+      self.height = height
+    }
+  }
+
+  public struct EquivalentRectangularDuctResponse: Codable, Equatable, Sendable {
+    public let height: Int
+    public let width: Int
+
+    public init(height: Int, width: Int) {
+      self.height = height
+      self.width = width
+    }
+  }
+}
diff --git a/Tests/ManualDClientTests/ManualDClientTests.swift b/Tests/ManualDClientTests/ManualDClientTests.swift
index dc9db5a..402281b 100644
--- a/Tests/ManualDClientTests/ManualDClientTests.swift
+++ b/Tests/ManualDClientTests/ManualDClientTests.swift
@@ -1,12 +1,19 @@
 import Dependencies
+import DependenciesTestSupport
 import Foundation
 import ManualDClient
 import ManualDCore
 import Testing
 
-@Suite("ManualDClient Tests")
+@Suite(
+  .dependencies {
+    $0.manualD = ManualDClient.liveValue
+  }
+)
 struct ManualDClientTests {
 
+  @Dependency(\.manualD) var manualD
+
   var numberFormatter: NumberFormatter {
     let formatter = NumberFormatter()
     formatter.minimumFractionDigits = 2
@@ -17,7 +24,6 @@ struct ManualDClientTests {
 
   @Test
   func frictionRate() async throws {
-    let manualD = ManualDClient.liveValue
     let response = try await manualD.frictionRate(
       .init(
         externalStaticPressure: 0.5,
@@ -32,7 +38,6 @@ struct ManualDClientTests {
   @Test
   func frictionRateFails() async throws {
     await #expect(throws: ManualDError.self) {
-      let manualD = ManualDClient.liveValue
       _ = try await manualD.frictionRate(
         .init(
           externalStaticPressure: 0.5,
@@ -42,4 +47,29 @@ struct ManualDClientTests {
       )
     }
   }
+
+  @Test
+  func totalEffectiveLength() async throws {
+    let response = try await manualD.totalEffectiveLength(
+      .init(
+        trunkLengths: [25],
+        runoutLengths: [10],
+        effectiveLengthGroups: [
+          // NOTE: These are made up and may not correspond to actual manual-d group tel's.
+          EffectiveLengthGroup(group: 1, letter: "a", effectiveLength: 20, category: .supply),
+          EffectiveLengthGroup(group: 2, letter: "a", effectiveLength: 30, category: .supply),
+          EffectiveLengthGroup(group: 3, letter: "a", effectiveLength: 10, category: .supply),
+          EffectiveLengthGroup(group: 12, letter: "a", effectiveLength: 10, category: .supply),
+        ]
+      )
+    )
+    #expect(response == 105)
+  }
+
+  @Test
+  func equivalentRectangularDuct() async throws {
+    let response = try await manualD.equivalentRectangularDuct(.init(round: 7, height: 8))
+    #expect(response.height == 8)
+    #expect(response.width == 5)
+  }
 }