仕組みと動作原理
NETWORKDAYS関数はExcel業務を効率化する代表的な関数です。開始日と終了日の間の実働日数（土日・祝日を除く稼働日数）を計算します。 複雑な集計や参照処理を簡素化し、データ分析の精度と生産性を飛躍的に高めます。
💡 わかりやすい要約
Counts the number of working days between two dates, automatically skipping weekends (Saturdays & Sundays) and holidays.
"Think of this like counting school days. It counts the days you have school, automatically skipping weekends and holidays."
構文.
標準Excel表記法=NETWORKDAYS(開始日, 終了日, [祭日])引数一覧.
この関数で指定できるすべての引数について詳しく解説します。
The starting date of the period.
指定例:A2The ending date of the period.
指定例:B2A range containing holiday dates to exclude.
指定例:E2:E3具体的な計算例
ステップ別の実務シナリオCalculate Project Working Days
Calculate the total billable working days between a project start and end date, excluding holidays.
| Start Date | End Date | Work Days | Holidays List | Holiday Date |
|---|---|---|---|---|
| 2026-08-03 | 2026-08-14 | — | Christmas | 2026-08-10 |
| 2026-08-05 | 2026-08-25 | — | New Year | 2026-08-21 |
| 2026-08-10 | 2026-08-21 | — | — | — |
=NETWORKDAYS(A2, B2, E2:E3)Evaluates NETWORKDAYS over the sample table cells, placing the verified output in cell C2:C6.
数式ジェネレーター
ウィザードを開く引数を入力するだけで、シートにそのまま貼り付けて使える数式を作成できます。
=NETWORKDAYS()出力される値の特性
Returns "Calculated output" based on sample evaluation criteria and active cell references.
実務上のベストプラクティス
- To calculate working days with custom weekend schedules (like Saturdays only or Friday/Saturdays), use the advanced `=NETWORKDAYS.INTL()` function instead.
よくあるミスと注意点
- Ensure your date values are real Excel serial dates or formatted text cells, rather than plain text that Excel fails to parse.
各プラットフォーム対応表
実際のExcelおよびGoogleスプレッドシートの計算エンジン仕様に基づいた検証結果です。
Core standard function supported across all modern and legacy Microsoft Excel versions (365, 2021, 2019, 2016, 2013, 2010), as well as Excel for the Web and Mac.
100% compatible with Google Sheets. Uses identical argument order, data types, and standard calculation logic.
よくある質問と回答
技術解説Can I use NETWORKDAYS across different worksheets in Excel?↓
Yes. You can reference cells located on other sheets by including the sheet name followed by an exclamation mark, for example: =NETWORKDAYS(Sheet2!A2:A10). If the sheet name contains spaces, enclose it in single quotes: ='Q1 Report'!A2:A10.
What is the most common reason for errors in NETWORKDAYS?↓
Ensure your date values are real Excel serial dates or formatted text cells, rather than plain text that Excel fails to parse.
Does NETWORKDAYS work identically in Google Sheets?↓
Yes, NETWORKDAYS is supported in both Microsoft Excel and Google Sheets with standard evaluation behavior.