小数時間から時刻変換ツール
小数時間（7.5など）を時:分:秒形式（7:30:00）に変換し、またその逆も可能です。タイムシート時間（7.5）を時刻値（7:30:00）に変換する際に便利です。
入力
時間数。例：7.5は7時間30分を意味します。
出力
| Unit | Value |
|---|---|
| No data yet | |
このツールを使う他の方法
REST API
curl -X POST https://api.iotools.cloud/v1/tool/decimal-to-time-converter \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"mode": "toTime",
"decimalHours": "7.5"
}'ご自身のアカウントのキーに差し替えてください。ツールのフィールドがそのままリクエストボディになります——ラッパーはありません。
AIエージェントに依頼する
Use the IOTools `decimal-to-time-converter` tool (Decimal to Time Converter) on this input:
YOUR_INPUT_HEREIOTools MCPサーバーに接続された任意のエージェントにこれを貼り付け、入力内容を追加してください。
埋め込みウィジェット
<iframe
src="https://iotools.cloud/embed/decimal-to-time-converter/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="小数時間から時刻変換ツール — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>ご自身のページに貼り付けるだけ——無料、キー不要、リンクを掲載するだけです。
| API/MCP 1回あたりの費用 | 5クレジットから |
|---|---|
| クレジットが足りませんか? | 料金を見る |
次の方法でも利用可能
ガイド
The Decimal to Time Converter turns decimal hours (like 7.5) into a clock value (7:30:00), and — unlike a one-way converter — also works in reverse: give it a clock time and it returns the equivalent decimal hours.
Why decimal hours need converting
Timesheets, payroll systems, and billing software often log time as decimal hours because they're easy to sum and multiply by an hourly rate. People, on the other hand, think and enter time as hours:minutes:seconds. Converting between the two by hand is easy to get wrong — 7.5 hours is 7 hours and 30 minutes, not 7 hours and 50 minutes, because the fractional part is a fraction of an hour (60 minutes), not of 100.
How to use it
- Pick a direction: Decimal hours → time or Time → decimal hours.
- Enter the value — a decimal number of hours (e.g.
7.5), or a clock time asH:MM:SSorH:MM(e.g.7:30:00or7:30). - Read the converted result, plus a full breakdown (hours/minutes/seconds, or decimal hours/minutes and total seconds).
How the conversion works
Decimal hours are multiplied by 3600 and rounded to the nearest whole second before being split into hours, minutes, and seconds — rounding at the second level (rather than rounding hours or minutes independently) avoids off-by-one artifacts like 7.999999 hours showing as 8:00:01. Converting the other way sums the clock value into whole seconds first, then divides by 3600 to get decimal hours, rounded to 6 decimal places.
Frequently asked questions
Why does 7.5 hours become 7:30:00, not 7:50:00? Because 0.5 of an hour is 30 minutes (half of 60), not 50. A quick way to check: multiply the decimal part by 60 — 0.5 × 60 = 30.
Can I convert negative values? No — this tool is built for timesheet and duration use, where hours are always zero or positive. For arithmetic on signed durations, see the Time Duration Formatter.
Is my input sent anywhere? No. The conversion runs entirely in your browser. Nothing you type is uploaded.