Voltage Drop Calculator - 無料オンライン電卓
A cable has resistance, so some voltage is lost along its length. Check that a wire size is thick enough for your current and distance.
- 計算式をページに表示
- ブラウザ内で動作
- 入力内容は非公開
Voltage drop
3.93 V
Percentage drop
1.71%
Voltage at load
226.1 V
Power lost in cable
79 W
The drop is within the usual 3% guideline.
DC resistance method at 20 degrees C. Real AC circuits add reactance for long or large cables. Follow your local wiring code.
一部のコンテンツはまだ英語で表示されます。
Voltage Drop Calculatorとは
Some tasks are specific enough that you'd normally reach for a separate app or browser extension - but really only come up once in a while. The Voltage Drop Calculator is the browser-based version: free, no account needed, works on any device, and the result is there in a few seconds. Nothing you enter is sent anywhere; everything happens on your device.
If the Voltage Drop Calculator is something you use regularly, bookmark it. Most of our utilities continue working offline once the page has loaded, which is handy when you're on a slow connection or need to get something done quickly without waiting for a server. The URL stays stable, so you can share it with anyone who needs the same tool.
Voltage Drop Calculatorの使い方（3ステップ）
Choose the circuit type, conductor and size.
Enter the one-way length and load current.
Check that the percentage drop is below about 3%.
Voltage Drop Calculatorのしくみ
Resistance equals resistivity times length divided by cross-section. The current flows out and back, so single-phase doubles the length.
Vd = 2 x I x R (single-phase) | Vd = 1.732 x I x R (three-phase)
- Rconductor resistance = rho x L / A
- Icurrent in amperes
Voltage Drop Calculatorが結果を出す方法
The Voltage Drop Calculator runs entirely in your browser. There's no upload, no remote server, no analytics on your inputs. For utilities that need fresh data (timezones, weather, currency rates), the calculator fetches from a public API - but only the bare query is sent, nothing about who you are.
Privacy and speed are the two design goals. The Voltage Drop Calculator is statically rendered so the page loads in under a second on most connections, and the actual computation happens on your device - typically in milliseconds. There's no spinner, no "calculating...", no waiting on someone else's server.
Voltage Drop Calculatorを使う場面
- One-off needs that don't justify installing an app or signing up for a service.
- Privacy-sensitive computations where you'd rather not send data to a third-party server.
- Quick checks on a phone or shared computer where installing software isn't an option.
- Teaching or demonstrating - the URL works the same on every device and platform.
よくある間違いと落とし穴
- Assuming a utility tool replaces a security audit. Password generators are good defaults, but truly sensitive accounts need a dedicated password manager.
- Treating output of a generator as a guarantee. Random number generators, dice rollers and similar tools use cryptographically-strong randomness, but you should still verify behaviour for any high-stakes use case.
- Forgetting that browser-side tools are subject to the device they run on. A compromised browser can leak inputs even if the tool itself doesn't transmit them.
- Not bookmarking the page if you'll use the Voltage Drop Calculator regularly - the URL is the cheapest way to find it again.
このツールを使いこなす
- Bookmark the Voltage Drop Calculator page if you use it more than once a week.
- Pair the Voltage Drop Calculator with other utilities on this site - many are designed to work together (e.g., date difference + age calculator, password generator + secure storage tools).
- Most utilities work offline after first load. Useful when you're on a flight or in patchy network conditions.
- Share the URL with anyone who needs the same tool - no install, no signup, just a link.
Voltage Drop Calculatorに関するよくある質問
What drop is acceptable?
Many codes recommend under 3% for a branch circuit and 5% overall.
How do I reduce voltage drop?
Use a larger conductor, shorten the run or reduce the current.
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Many tools in the Daily Utilities category complement each other - date difference + day counter + day-of-the-week, or password generator + QR code + base64 encoder. The related-tool grid links them together so you can move between adjacent problems in a click.
The Voltage Drop Calculator is part of the Daily Utilities suite on Online Calculator Tools, alongside 5 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.