Ohm's Law Calculator - 無料オンライン電卓
Ohm's law links voltage, current, resistance and power. Fill in any two and the other two are calculated.
- 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
12 V
Current
2 A
Resistance
6 Ω
Power
24 W
一部のコンテンツはまだ英語で表示されます。
Ohm's Law 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 Ohm's Law 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 Ohm's Law 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.
Ohm's Law Calculatorの使い方（3ステップ）
Enter two of the four values.
Leave the other two boxes empty.
Read the calculated values.
Ohm's Law Calculatorのしくみ
Voltage equals current times resistance, and power equals voltage times current. Combining them gives every pair of relationships.
V = I x R | P = V x I | P = I^2 x R | P = V^2 / R
- Vvolts
- Iamperes
- Rohms
- Pwatts
Ohm's Law Calculatorが結果を出す方法
The Ohm's Law 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 Ohm's Law 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.
Ohm's Law 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 Ohm's Law 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 Ohm's Law Calculator page if you use it more than once a week.
- Pair the Ohm's Law 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.
Ohm's Law Calculatorに関するよくある質問
Why do I need exactly two values?
Two independent values fix the other two. Three would be redundant or inconsistent.
Does it work for AC?
Yes for resistive loads. Reactive loads need impedance and power factor.
Small tools that save real time
Date math, password generation, QR codes, IP subnets, base64 encoding, dew point, dice rolls, age calculations - none of these are 'big' problems individually, but they are the small frictions that interrupt your day. This tool runs entirely in your browser, has no popup, no chat widget and no tracking inside the calculation, so you can finish the task and move on.
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 Ohm's Law 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.