diff --git a/docs/plan/#18-goal-task-stats/checklist.md b/docs/plan/#18-goal-task-stats/checklist.md
new file mode 100644
index 0000000..f85dc93
--- /dev/null
+++ b/docs/plan/#18-goal-task-stats/checklist.md
@@ -0,0 +1,12 @@
+# Goal 타입 달성률/통계 검증 체크리스트
+
+## 필수 항목
+- [x] 아키텍처 원칙 준수 (docs/architecture.md 기준)
+- [x] 레이어 의존성 규칙 위반 없음
+- [x] BC 간 참조 규칙 준수 (Task BC가 Goal 타입 필드 resolve)
+- [x] 테스트 코드 작성 완료 (Domain, Application 필수)
+- [x] 모든 테스트 통과
+- [x] 기존 테스트 깨지지 않음
+
+## 선택 항목
+- [x] DataLoader로 N+1 방지 확인
diff --git a/docs/plan/#18-goal-task-stats/plan.md b/docs/plan/#18-goal-task-stats/plan.md
new file mode 100644
index 0000000..a3cddc6
--- /dev/null
+++ b/docs/plan/#18-goal-task-stats/plan.md
@@ -0,0 +1,22 @@
+# Goal 타입에 달성률/통계 computed fields 추가 계획
+
+> Issue: #18
+
+## 설계 방향
+
+- Goal GraphQL 타입에 `completedTaskCount`, `totalTaskCount`, `achievementRate` 필드 추가
+- DB 저장 없이 응답 시 Task 데이터 기반으로 계산
+- DataLoader로 N+1 방지 (Goal 목록 조회 시 한 번의 batch 쿼리)
+- **BC 간 참조 규칙 준수**: Task BC의 DataFetcher가 Goal 타입의 통계 필드를 resolve
+  - Goal BC는 Task BC를 참조하지 않음
+  - Task BC의 Presentation 레이어에서 `@DgsData(parentType = "Goal")` 사용
+
+## 단계
+
+- [x] 1단계: GraphQL 스키마 — Goal 타입에 통계 필드 추가
+- [x] 2단계: Domain — GoalTaskStats 모델 + TaskRepository에 `countByGoalIds` 추가 (TDD)
+- [x] 3단계: Application — TaskService에 `getStatsByGoalIds` 메서드 추가 (TDD)
+- [x] 4단계: Infrastructure — ExposedTaskRepository에 집계 쿼리 구현
+- [x] 5단계: Presentation — GoalTaskStatsDataLoader + GoalTaskStatsDataFetcher 구현
+- [x] 6단계: 전체 테스트 통과 확인 및 검증
+- [ ] 7단계: 리팩토링 — 집계 로직을 Infrastructure에서 Application으로 이동
diff --git a/src/main/kotlin/kr/io/team/loop/goal/presentation/datafetcher/GoalDataFetcher.kt b/src/main/kotlin/kr/io/team/loop/goal/presentation/datafetcher/GoalDataFetcher.kt
index eab46ee..54126c6 100644
--- a/src/main/kotlin/kr/io/team/loop/goal/presentation/datafetcher/GoalDataFetcher.kt
+++ b/src/main/kotlin/kr/io/team/loop/goal/presentation/datafetcher/GoalDataFetcher.kt
@@ -70,5 +70,8 @@ class GoalDataFetcher(
             title = title.value,
             createdAt = createdAt.toString(),
             updatedAt = updatedAt?.toString(),
+            totalTaskCount = 0,
+            completedTaskCount = 0,
+            achievementRate = 0.0,
         )
 }
diff --git a/src/main/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDto.kt b/src/main/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDto.kt
new file mode 100644
index 0000000..5570916
--- /dev/null
+++ b/src/main/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDto.kt
@@ -0,0 +1,12 @@
+package kr.io.team.loop.task.application.dto
+
+import kr.io.team.loop.common.domain.GoalId
+
+data class GoalTaskStatsDto(
+    val goalId: GoalId,
+    val totalCount: Int,
+    val completedCount: Int,
+) {
+    val achievementRate: Double
+        get() = if (totalCount == 0) 0.0 else (completedCount.toDouble() / totalCount) * 100.0
+}
diff --git a/src/main/kotlin/kr/io/team/loop/task/application/service/TaskService.kt b/src/main/kotlin/kr/io/team/loop/task/application/service/TaskService.kt
index 9df1635..163f549 100644
--- a/src/main/kotlin/kr/io/team/loop/task/application/service/TaskService.kt
+++ b/src/main/kotlin/kr/io/team/loop/task/application/service/TaskService.kt
@@ -1,11 +1,14 @@
 package kr.io.team.loop.task.application.service
 
+import kr.io.team.loop.common.domain.GoalId
 import kr.io.team.loop.common.domain.MemberId
 import kr.io.team.loop.common.domain.exception.AccessDeniedException
 import kr.io.team.loop.common.domain.exception.EntityNotFoundException
+import kr.io.team.loop.task.application.dto.GoalTaskStatsDto
 import kr.io.team.loop.task.domain.model.Task
 import kr.io.team.loop.task.domain.model.TaskCommand
 import kr.io.team.loop.task.domain.model.TaskQuery
+import kr.io.team.loop.task.domain.model.TaskStatus
 import kr.io.team.loop.task.domain.repository.TaskRepository
 import org.springframework.stereotype.Service
 import org.springframework.transaction.annotation.Transactional
@@ -34,6 +37,21 @@ class TaskService(
         return taskRepository.updateStatus(command)
     }
 
+    @Transactional(readOnly = true)
+    fun getStatsByGoalIds(goalIds: Set<GoalId>): Map<GoalId, GoalTaskStatsDto> {
+        val tasks = taskRepository.findAllByGoalIds(goalIds)
+        return tasks
+            .groupBy { it.goalId }
+            .map { (goalId, goalTasks) ->
+                goalId to
+                    GoalTaskStatsDto(
+                        goalId = goalId,
+                        totalCount = goalTasks.size,
+                        completedCount = goalTasks.count { it.status == TaskStatus.DONE },
+                    )
+            }.toMap()
+    }
+
     @Transactional
     fun delete(
         command: TaskCommand.Delete,
diff --git a/src/main/kotlin/kr/io/team/loop/task/domain/repository/TaskRepository.kt b/src/main/kotlin/kr/io/team/loop/task/domain/repository/TaskRepository.kt
index 1c33bf0..25fca01 100644
--- a/src/main/kotlin/kr/io/team/loop/task/domain/repository/TaskRepository.kt
+++ b/src/main/kotlin/kr/io/team/loop/task/domain/repository/TaskRepository.kt
@@ -1,5 +1,6 @@
 package kr.io.team.loop.task.domain.repository
 
+import kr.io.team.loop.common.domain.GoalId
 import kr.io.team.loop.common.domain.TaskId
 import kr.io.team.loop.task.domain.model.Task
 import kr.io.team.loop.task.domain.model.TaskCommand
@@ -15,4 +16,6 @@ interface TaskRepository {
     fun findAll(query: TaskQuery): List<Task>
 
     fun findById(id: TaskId): Task?
+
+    fun findAllByGoalIds(goalIds: Set<GoalId>): List<Task>
 }
diff --git a/src/main/kotlin/kr/io/team/loop/task/infrastructure/persistence/ExposedTaskRepository.kt b/src/main/kotlin/kr/io/team/loop/task/infrastructure/persistence/ExposedTaskRepository.kt
index 98ec23c..6757f5b 100644
--- a/src/main/kotlin/kr/io/team/loop/task/infrastructure/persistence/ExposedTaskRepository.kt
+++ b/src/main/kotlin/kr/io/team/loop/task/infrastructure/persistence/ExposedTaskRepository.kt
@@ -15,6 +15,7 @@ import org.jetbrains.exposed.v1.core.SortOrder
 import org.jetbrains.exposed.v1.core.and
 import org.jetbrains.exposed.v1.core.eq
 import org.jetbrains.exposed.v1.core.greaterEq
+import org.jetbrains.exposed.v1.core.inList
 import org.jetbrains.exposed.v1.core.lessEq
 import org.jetbrains.exposed.v1.jdbc.deleteWhere
 import org.jetbrains.exposed.v1.jdbc.insert
@@ -81,6 +82,15 @@ class ExposedTaskRepository : TaskRepository {
             .singleOrNull()
             ?.toTask()
 
+    override fun findAllByGoalIds(goalIds: Set<GoalId>): List<Task> {
+        if (goalIds.isEmpty()) return emptyList()
+        val goalIdValues = goalIds.map { it.value }
+        return TaskTable
+            .selectAll()
+            .where { TaskTable.goalId inList goalIdValues }
+            .map { it.toTask() }
+    }
+
     private fun ResultRow.toTask(): Task =
         Task(
             id = TaskId(this[TaskTable.taskId]),
diff --git a/src/main/kotlin/kr/io/team/loop/task/presentation/datafetcher/GoalTaskStatsDataFetcher.kt b/src/main/kotlin/kr/io/team/loop/task/presentation/datafetcher/GoalTaskStatsDataFetcher.kt
new file mode 100644
index 0000000..142af18
--- /dev/null
+++ b/src/main/kotlin/kr/io/team/loop/task/presentation/datafetcher/GoalTaskStatsDataFetcher.kt
@@ -0,0 +1,32 @@
+package kr.io.team.loop.task.presentation.datafetcher
+
+import com.netflix.graphql.dgs.DgsComponent
+import com.netflix.graphql.dgs.DgsData
+import com.netflix.graphql.dgs.DgsDataFetchingEnvironment
+import kr.io.team.loop.codegen.types.Goal
+import kr.io.team.loop.task.application.dto.GoalTaskStatsDto
+import java.util.concurrent.CompletableFuture
+
+@DgsComponent
+class GoalTaskStatsDataFetcher {
+    @DgsData(parentType = "Goal", field = "totalTaskCount")
+    fun totalTaskCount(dfe: DgsDataFetchingEnvironment): CompletableFuture<Int> {
+        val goal = dfe.getSource<Goal>()!!
+        val dataLoader = dfe.getDataLoader<Long, GoalTaskStatsDto>("goalTaskStats")!!
+        return dataLoader.load(goal.id.toLong()).thenApply { it?.totalCount ?: 0 }
+    }
+
+    @DgsData(parentType = "Goal", field = "completedTaskCount")
+    fun completedTaskCount(dfe: DgsDataFetchingEnvironment): CompletableFuture<Int> {
+        val goal = dfe.getSource<Goal>()!!
+        val dataLoader = dfe.getDataLoader<Long, GoalTaskStatsDto>("goalTaskStats")!!
+        return dataLoader.load(goal.id.toLong()).thenApply { it?.completedCount ?: 0 }
+    }
+
+    @DgsData(parentType = "Goal", field = "achievementRate")
+    fun achievementRate(dfe: DgsDataFetchingEnvironment): CompletableFuture<Double> {
+        val goal = dfe.getSource<Goal>()!!
+        val dataLoader = dfe.getDataLoader<Long, GoalTaskStatsDto>("goalTaskStats")!!
+        return dataLoader.load(goal.id.toLong()).thenApply { it?.achievementRate ?: 0.0 }
+    }
+}
diff --git a/src/main/kotlin/kr/io/team/loop/task/presentation/dataloader/GoalTaskStatsDataLoader.kt b/src/main/kotlin/kr/io/team/loop/task/presentation/dataloader/GoalTaskStatsDataLoader.kt
new file mode 100644
index 0000000..71c332d
--- /dev/null
+++ b/src/main/kotlin/kr/io/team/loop/task/presentation/dataloader/GoalTaskStatsDataLoader.kt
@@ -0,0 +1,21 @@
+package kr.io.team.loop.task.presentation.dataloader
+
+import com.netflix.graphql.dgs.DgsDataLoader
+import kr.io.team.loop.common.domain.GoalId
+import kr.io.team.loop.task.application.dto.GoalTaskStatsDto
+import kr.io.team.loop.task.application.service.TaskService
+import org.dataloader.MappedBatchLoader
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.CompletionStage
+
+@DgsDataLoader(name = "goalTaskStats")
+class GoalTaskStatsDataLoader(
+    private val taskService: TaskService,
+) : MappedBatchLoader<Long, GoalTaskStatsDto> {
+    override fun load(keys: Set<Long>): CompletionStage<Map<Long, GoalTaskStatsDto>> =
+        CompletableFuture.supplyAsync {
+            val goalIds = keys.map { GoalId(it) }.toSet()
+            val stats = taskService.getStatsByGoalIds(goalIds)
+            stats.map { (goalId, goalTaskStats) -> goalId.value to goalTaskStats }.toMap()
+        }
+}
diff --git a/src/main/resources/schema/goal.graphqls b/src/main/resources/schema/goal.graphqls
index 4a2f8c5..ff50282 100644
--- a/src/main/resources/schema/goal.graphqls
+++ b/src/main/resources/schema/goal.graphqls
@@ -24,6 +24,12 @@ type Goal {
     createdAt: String!
     "수정일시"
     updatedAt: String
+    "해당 목표의 전체 할일 수"
+    totalTaskCount: Int!
+    "해당 목표의 완료된 할일 수"
+    completedTaskCount: Int!
+    "해당 목표의 달성률 (0.0 ~ 100.0, 할일이 없으면 0.0)"
+    achievementRate: Float!
 }
 
 "목표 생성 입력"
diff --git a/src/test/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDtoTest.kt b/src/test/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDtoTest.kt
new file mode 100644
index 0000000..2a35251
--- /dev/null
+++ b/src/test/kotlin/kr/io/team/loop/task/application/dto/GoalTaskStatsDtoTest.kt
@@ -0,0 +1,43 @@
+package kr.io.team.loop.task.application.dto
+
+import io.kotest.core.spec.style.BehaviorSpec
+import io.kotest.matchers.shouldBe
+import kr.io.team.loop.common.domain.GoalId
+
+class GoalTaskStatsDtoTest :
+    BehaviorSpec({
+
+        Given("GoalTaskStatsDto 달성률 계산 시") {
+            When("할일이 있으면") {
+                val stats = GoalTaskStatsDto(goalId = GoalId(1L), totalCount = 10, completedCount = 7)
+
+                Then("달성률을 백분율로 반환한다") {
+                    stats.achievementRate shouldBe 70.0
+                }
+            }
+
+            When("모든 할일이 완료되면") {
+                val stats = GoalTaskStatsDto(goalId = GoalId(1L), totalCount = 5, completedCount = 5)
+
+                Then("달성률 100.0을 반환한다") {
+                    stats.achievementRate shouldBe 100.0
+                }
+            }
+
+            When("할일이 없으면") {
+                val stats = GoalTaskStatsDto(goalId = GoalId(1L), totalCount = 0, completedCount = 0)
+
+                Then("달성률 0.0을 반환한다") {
+                    stats.achievementRate shouldBe 0.0
+                }
+            }
+
+            When("완료된 할일이 없으면") {
+                val stats = GoalTaskStatsDto(goalId = GoalId(1L), totalCount = 3, completedCount = 0)
+
+                Then("달성률 0.0을 반환한다") {
+                    stats.achievementRate shouldBe 0.0
+                }
+            }
+        }
+    })
diff --git a/src/test/kotlin/kr/io/team/loop/task/application/service/TaskServiceTest.kt b/src/test/kotlin/kr/io/team/loop/task/application/service/TaskServiceTest.kt
index 57b443e..f348d04 100644
--- a/src/test/kotlin/kr/io/team/loop/task/application/service/TaskServiceTest.kt
+++ b/src/test/kotlin/kr/io/team/loop/task/application/service/TaskServiceTest.kt
@@ -129,6 +129,49 @@ class TaskServiceTest :
             }
         }
 
+        Given("목표별 할일 통계 조회 시") {
+            val goalId1 = GoalId(1L)
+            val goalId2 = GoalId(2L)
+
+            fun task(
+                goalId: GoalId,
+                status: TaskStatus,
+            ) = savedTask.copy(goalId = goalId, status = status)
+
+            When("할일이 있는 목표들이면") {
+                val goalIds = setOf(goalId1, goalId2)
+                val tasks =
+                    listOf(
+                        task(goalId1, TaskStatus.TODO),
+                        task(goalId1, TaskStatus.DONE),
+                        task(goalId1, TaskStatus.DONE),
+                        task(goalId2, TaskStatus.DONE),
+                    )
+                every { taskRepository.findAllByGoalIds(goalIds) } returns tasks
+
+                val result = taskService.getStatsByGoalIds(goalIds)
+
+                Then("목표별 통계를 반환한다") {
+                    result[goalId1]!!.totalCount shouldBe 3
+                    result[goalId1]!!.completedCount shouldBe 2
+                    result[goalId2]!!.totalCount shouldBe 1
+                    result[goalId2]!!.completedCount shouldBe 1
+                    result[goalId2]!!.achievementRate shouldBe 100.0
+                }
+            }
+
+            When("빈 goalIds이면") {
+                val goalIds = emptySet<GoalId>()
+                every { taskRepository.findAllByGoalIds(goalIds) } returns emptyList()
+
+                val result = taskService.getStatsByGoalIds(goalIds)
+
+                Then("빈 맵을 반환한다") {
+                    result shouldBe emptyMap()
+                }
+            }
+        }
+
         Given("할일 삭제 시") {
             When("본인 할일이면") {
                 val command = TaskCommand.Delete(taskId = TaskId(1L))