diff --git a/Sources/DatabaseClient/EffectiveLength.swift b/Sources/DatabaseClient/EffectiveLength.swift
new file mode 100644
index 0000000..cf72d10
--- /dev/null
+++ b/Sources/DatabaseClient/EffectiveLength.swift
@@ -0,0 +1,158 @@
+import Dependencies
+import DependenciesMacros
+import Fluent
+import Foundation
+import ManualDCore
+
+extension DatabaseClient {
+  @DependencyClient
+  public struct EffectiveLengthClient: Sendable {
+    public var create: @Sendable (EffectiveLength.Create) async throws -> EffectiveLength
+    public var delete: @Sendable (EffectiveLength.ID) async throws -> Void
+    public var fetch: @Sendable (Project.ID) async throws -> EffectiveLength?
+    public var get: @Sendable (EffectiveLength.ID) async throws -> EffectiveLength?
+  }
+}
+
+extension DatabaseClient.EffectiveLengthClient: TestDependencyKey {
+  public static let testValue = Self()
+
+  public static func live(database: any Database) -> Self {
+    .init(
+      create: { request in
+        let model = try request.toModel()
+        try await model.save(on: database)
+        return try model.toDTO()
+      },
+      delete: { id in
+        guard let model = try await EffectiveLengthModel.find(id, on: database) else {
+          throw NotFoundError()
+        }
+        try await model.delete(on: database)
+      },
+      fetch: { projectID in
+        guard
+          let model = try await EffectiveLengthModel.query(on: database)
+            .filter("projectID", .equal, projectID)
+            .first()
+        else {
+          throw NotFoundError()
+        }
+
+        return try model.toDTO()
+      },
+      get: { id in
+        try await EffectiveLengthModel.find(id, on: database).map { try $0.toDTO() }
+      }
+    )
+  }
+}
+
+extension EffectiveLength.Create {
+
+  func toModel() throws -> EffectiveLengthModel {
+    try validate()
+    return try .init(
+      name: name,
+      type: type.rawValue,
+      straightLengths: straightLengths,
+      groups: JSONEncoder().encode(groups),
+      projectID: projectID
+    )
+  }
+
+  func validate() throws(ValidationError) {
+    guard !name.isEmpty else {
+      throw ValidationError("Effective length name can not be empty.")
+    }
+  }
+}
+
+extension EffectiveLength {
+
+  struct Migrate: AsyncMigration {
+    let name = "CreateEffectiveLength"
+
+    func prepare(on database: any Database) async throws {
+      try await database.schema(EffectiveLengthModel.schema)
+        .id()
+        .field("name", .string, .required)
+        .field("type", .string, .required)
+        .field("straightLengths", .array(of: .int))
+        .field("groups", .data)
+        .field("createdAt", .datetime)
+        .field("updatedAt", .datetime)
+        .field("projectID", .uuid, .required, .references(ProjectModel.schema, "id"))
+        .unique(on: "projectID", "name", "type")
+        .create()
+    }
+
+    func revert(on database: any Database) async throws {
+      try await database.schema(EffectiveLengthModel.schema).delete()
+    }
+  }
+}
+
+final class EffectiveLengthModel: Model, @unchecked Sendable {
+
+  static let schema = "effective_length"
+
+  @ID(key: .id)
+  var id: UUID?
+
+  @Field(key: "name")
+  var name: String
+
+  @Field(key: "type")
+  var type: String
+
+  @Field(key: "straightLengths")
+  var straightLengths: [Int]
+
+  @Field(key: "groups")
+  var groups: Data
+
+  @Timestamp(key: "createdAt", on: .create, format: .iso8601)
+  var createdAt: Date?
+
+  @Timestamp(key: "updatedAt", on: .update, format: .iso8601)
+  var updatedAt: Date?
+
+  @Parent(key: "projectID")
+  var project: ProjectModel
+
+  init() {}
+
+  init(
+    id: UUID? = nil,
+    name: String,
+    type: String,
+    straightLengths: [Int],
+    groups: Data,
+    createdAt: Date? = nil,
+    updatedAt: Date? = nil,
+    projectID: Project.ID
+  ) {
+    self.id = id
+    self.name = name
+    self.type = type
+    self.straightLengths = straightLengths
+    self.groups = groups
+    self.createdAt = createdAt
+    self.updatedAt = updatedAt
+    $project.id = projectID
+  }
+
+  func toDTO() throws -> EffectiveLength {
+    try .init(
+      id: requireID(),
+      projectID: $project.id,
+      name: name,
+      type: .init(rawValue: type)!,
+      straightLengths: straightLengths,
+      groups: JSONDecoder().decode([EffectiveLength.Group].self, from: groups),
+      createdAt: createdAt!,
+      updatedAt: updatedAt!
+    )
+  }
+}
diff --git a/Sources/DatabaseClient/Interface.swift b/Sources/DatabaseClient/Interface.swift
index ea6a11e..afff9cf 100644
--- a/Sources/DatabaseClient/Interface.swift
+++ b/Sources/DatabaseClient/Interface.swift
@@ -17,6 +17,7 @@ public struct DatabaseClient: Sendable {
   public var rooms: Rooms
   public var equipment: Equipment
   public var componentLoss: ComponentLoss
+  public var effectiveLength: EffectiveLengthClient
 }
 
 extension DatabaseClient: TestDependencyKey {
@@ -25,7 +26,8 @@ extension DatabaseClient: TestDependencyKey {
     projects: .testValue,
     rooms: .testValue,
     equipment: .testValue,
-    componentLoss: .testValue
+    componentLoss: .testValue,
+    effectiveLength: .testValue
   )
 
   public static func live(database: any Database) -> Self {
@@ -34,7 +36,8 @@ extension DatabaseClient: TestDependencyKey {
       projects: .live(database: database),
       rooms: .live(database: database),
       equipment: .live(database: database),
-      componentLoss: .live(database: database)
+      componentLoss: .live(database: database),
+      effectiveLength: .live(database: database)
     )
   }
 }
@@ -58,6 +61,7 @@ extension DatabaseClient.Migrations: DependencyKey {
         ComponentPressureLoss.Migrate(),
         EquipmentInfo.Migrate(),
         Room.Migrate(),
+        EffectiveLength.Migrate(),
       ]
     }
   )
diff --git a/Sources/ManualDCore/EffectiveLength.swift b/Sources/ManualDCore/EffectiveLength.swift
new file mode 100644
index 0000000..379d4cb
--- /dev/null
+++ b/Sources/ManualDCore/EffectiveLength.swift
@@ -0,0 +1,87 @@
+import Foundation
+
+// TODO: Not sure how to model effective length groups in the database.
+//       thinking perhaps just have a 'data' field that encoded / decodes
+//       to swift types??
+public struct EffectiveLength: Codable, Equatable, Identifiable, Sendable {
+
+  public let id: UUID
+  public let projectID: Project.ID
+  public let name: String
+  public let type: EffectiveLengthType
+  public let straightLengths: [Int]
+  public let groups: [Group]
+  public let createdAt: Date
+  public let updatedAt: Date
+
+  public init(
+    id: UUID,
+    projectID: Project.ID,
+    name: String,
+    type: EffectiveLength.EffectiveLengthType,
+    straightLengths: [Int],
+    groups: [EffectiveLength.Group],
+    createdAt: Date,
+    updatedAt: Date
+  ) {
+    self.id = id
+    self.projectID = projectID
+    self.name = name
+    self.type = type
+    self.straightLengths = straightLengths
+    self.groups = groups
+    self.createdAt = createdAt
+    self.updatedAt = updatedAt
+  }
+}
+
+extension EffectiveLength {
+
+  public struct Create: Codable, Equatable, Sendable {
+
+    public let projectID: Project.ID
+    public let name: String
+    public let type: EffectiveLengthType
+    public let straightLengths: [Int]
+    public let groups: [Group]
+
+    public init(
+      projectID: Project.ID,
+      name: String,
+      type: EffectiveLength.EffectiveLengthType,
+      straightLengths: [Int],
+      groups: [EffectiveLength.Group]
+    ) {
+      self.projectID = projectID
+      self.name = name
+      self.type = type
+      self.straightLengths = straightLengths
+      self.groups = groups
+    }
+  }
+
+  public enum EffectiveLengthType: String, CaseIterable, Codable, Sendable {
+    case `return`
+    case supply
+  }
+
+  public struct Group: Codable, Equatable, Sendable {
+
+    public let group: Int
+    public let letter: String
+    public let value: Double
+    public let quantity: Int
+
+    public init(
+      group: Int,
+      letter: String,
+      value: Double,
+      quantity: Int = 1
+    ) {
+      self.group = group
+      self.letter = letter
+      self.value = value
+      self.quantity = quantity
+    }
+  }
+}
diff --git a/Sources/ManualDCore/Routes/ApiRoute.swift b/Sources/ManualDCore/Routes/ApiRoute.swift
index 762fe11..35f53b2 100644
--- a/Sources/ManualDCore/Routes/ApiRoute.swift
+++ b/Sources/ManualDCore/Routes/ApiRoute.swift
@@ -192,3 +192,48 @@ extension SiteRoute.Api {
     }
   }
 }
+
+extension SiteRoute.Api {
+  public enum EffectiveLengthRoute: Equatable, Sendable {
+    case create(EffectiveLength.Create)
+    case delete(id: EffectiveLength.ID)
+    case fetch(projectID: Project.ID)
+    case get(id: EffectiveLength.ID)
+
+    static let rootPath = "effectiveLength"
+
+    public static let router = OneOf {
+      Route(.case(Self.create)) {
+        Path {
+          rootPath
+          "create"
+        }
+        Method.post
+        Body(.json(EffectiveLength.Create.self))
+      }
+      Route(.case(Self.delete(id:))) {
+        Path {
+          rootPath
+          EffectiveLength.ID.parser()
+        }
+        Method.delete
+      }
+      Route(.case(Self.fetch(projectID:))) {
+        Path {
+          rootPath
+        }
+        Method.get
+        Query {
+          Field("projectID") { Project.ID.parser() }
+        }
+      }
+      Route(.case(Self.get(id:))) {
+        Path {
+          rootPath
+          EffectiveLength.ID.parser()
+        }
+        Method.get
+      }
+    }
+  }
+}