Circuits
Enter any two electrical values and solve the other two, then check resistor networks and power-rating safety margins.
Calculator
Every input updates the result, visual proof, report, code snippets and printable worksheet in the browser.
Network equivalent: 200 ohm from 2 resistor(s).
12 V, 3 A, 4 ohm and 36 W.
Use it in code
V = 12
I = 3
R = V / I
P = V * I
print(f"voltage={V:.6g}")
print(f"current={I:.6g}")
print(f"resistance={R:.6g}")
print(f"power={P:.6g}")The snippets use the current inputs and print the same headline result.
Print room
The worksheet records the inputs, formula, result and a short check prompt.
CalculationTime Phase 4 worksheet
12 V, 3 A, 4 ohm and 36 W.
| Input A | 12 |
|---|---|
| Input B / mode | 3 |
| Input C | |
| Input D | 4 |
| Voltage | 12 V |
|---|---|
| Current | 3 A |
| Resistance | 4 ohm |
| Power | 36 W |
| 2x power rating | 72 W |
Confirm units, constants, rounding and the real-world assumption before using the number outside this worksheet.
Method
Search intent: Best answer for V, I, R and P from any two known electrical quantities.
Nearest sibling: Different from an energy or power converter because it models a circuit relationship and resistor network, not just a unit conversion.
Ohm's law ties voltage, current and resistance together: V = I x R. Power then follows from P = V x I, with equivalent forms P = I^2 x R and P = V^2 / R. The page accepts any two known values and shows which formula path it used, so the user can tell whether the answer came from a direct voltage-current pair, a resistance-power pair, or another valid combination.
Series and parallel resistors answer a different but common circuit question. Series resistances add directly. Parallel resistances add by reciprocals, which is why 100 ohm in parallel with 100 ohm gives 50 ohm. The live circuit drawing changes with the mode and the V-I line marks the operating point so slope, current and voltage remain connected.
The power-rating check is intentionally conservative. If the circuit dissipates 36 W in a resistor, the page says the resistor should be rated at least 72 W for a simple 2x planning margin. Real designs also need temperature, enclosure, tolerance and safety standards.
The SI prefix controls matter because real circuit work moves between milliamps, amps, kilohms and megohms constantly. Treating every input as a bare base unit invites errors such as reading 4.7 k ohm as 4.7 ohm or 20 mA as 20 A. The calculator keeps the displayed entry separate from the base-unit solve, so the report can show the actual V, A, ohm and W values used by the formula.
The page follows the CalculationTime five-beat pattern: name the inputs, state the intent, calculate the result, show proof, then make the output portable. The live diagram is not decoration; it is another view of the same state, so changing an input must visibly change the geometry. The code snippets are the second audit trail. They use the current numbers and standard libraries where available, which lets a reader repeat the result without trusting the browser UI alone. The report button turns the current state into plain Markdown, which is useful for classroom notes, lab records, engineering comments, tutoring answers and audit trails because it carries inputs, assumptions and results together instead of leaving a screenshot with no method. The worksheet does a different job: it slows the calculation down enough for a person to check units, copy the formula, circle assumptions and compare the output with an official document or source. Those two outputs are deliberately boring and portable because boring portable proof is what survives after the browser tab is closed.
The source boundary is also part of the design. Constants that are exact by definition, such as inch-to-metre, pound-to-kilogram, byte prefixes and standard gravity, are separated from approximations and rules of thumb. Security pages distinguish checksums, encodings and encryption because those words are often misused in search results. Physics pages name their model limits before giving a crisp answer because a clean drag-free arc or ideal energy transfer can be mathematically correct while still being incomplete for a real projectile, falling object or electrical assembly. This is why every page carries both a direct answer and a method section: the answer is fast, but the method tells the user when the answer is allowed to matter. A good calculator page also has to survive the second question, not just the first. After the headline result, users ask what changed, what was assumed, how to repeat it, and whether a neighbouring page would have answered a different intent. Phase 4 pages therefore keep the controls, visual, code, worksheet and sources close together so the user can trace the same state through several forms of proof without hunting around the site. That repeated structure is intentional: once a visitor learns where the proof, copy button and worksheet live on one technical calculator, the next technical page becomes faster to audit and harder to misuse.
Common mistakes
Every page names the units, constants and model boundary. Change those first if your real problem uses a different standard, gravity, encoding or electrical configuration.
The interface rounds for readability. Use the code panel or copied report when you need repeatable decimal places for a calculation log.
One URL should answer one intent. Use the page that matches the job: a universal converter for units, Ohm's law for circuits, hash generator for checksums, and Base64 for encoding.
Projectile motion ignores drag, hashes are not encryption, Base64 is not security, and electrical safety needs rated parts and competent review.
Sources
Questions people ask
No. These Phase 4 tools compute in the browser from local formula and reference tables.
The snippets are a second proof path. They use the current inputs and print the same headline result so the arithmetic can be checked outside the page.
Definitions such as inch, pound, atmosphere, byte prefixes and standard gravity are labelled from standards sources. Approximations are described as planning examples.
It copies Markdown with the page URL, input values, assumptions and displayed results, plus CSV for table-friendly results.
No. These pages explain and check calculations, but they are not a substitute for standards compliance, engineering review, lender documents or security practice.
Need this as JSON? See the CalculationTime API developer portal: https://byebilly.github.io/calculationtime-web/
Certification notes
Phase 4 browser-only calculator page with live proof, code snippets, report copy and worksheet. Reviewed 2026-09-22.
The page is an educational browser calculator. It does not replace standards documents, engineering judgement, financial documents, security review or professional advice.
Use the canonical URL, the page title “Ohm's Law Calculator - CalculationTime”, and the review date 2026-09-22.