Cable Sizing Calculator
Wire size from current and voltage drop
🔒 On-device · Method · · Disclaimer · Cable Sizing Calculator
Cable Sizing Calculator turns the numbers behind wire size from current and voltage drop into a result, step by step. You supply Current (A), Cable Length (m) and Max Voltage Drop (%) to Cable Sizing; the answer follows at once. Cable Sizing displays each intermediate figure as well. Cable Sizing replaces guesswork. No account is needed for Cable Sizing. The browser does the arithmetic. Cable Sizing is part of the Engineering collection on CalcProMaster, alongside cable sizing calculator wire ampacity voltage drop, free online cable sizing calculator and more. Cable Sizing is designed for real people. Labels stay plain. Open Cable Sizing and enter your numbers.
What does the Cable Sizing Calculator do?
Cable Sizing Calculator works out the min area from the Current, Cable Length, and Max Voltage Drop, using Engineering conventions. With the defaults, cable sizing calculator gives a min area of 5.0 mm².
- Inputs: Current, Cable Length, and Max Voltage Drop.
- Output: the min area, and the operations that led to it.
- Method: the Engineering formula, applied to Current, Cable Length, and Max Voltage Drop inside the browser tab.
Quick answer
cable sizing calculator returns a min area of 5.0 mm² with the default inputs (current of 20, cable length of 50, max voltage drop of 3).
How does the Cable Sizing Calculator work?
Cable Sizing Calculator computes the min area directly from your inputs — the Current, Cable Length, and Max Voltage Drop feed the formula. The min area is worked out on the device, so nothing about your inputs is transmitted.
How it works
Cable Sizing Calculator is built for cable sizing questions that need a defensible number: the working is always visible, the inputs accept your own values, and the figure updates as you type.
Using the Cable Sizing Calculator
- Current — the Engineering field that most often arrives from another document; re-check its scale.
- Cable Length — read literally by the cable sizing formula, so a placeholder produces a placeholder answer.
- Max Voltage Drop — the field the rest of the cable sizing case hangs on; revisit it to move the min area.
- Start at the result on Cable Sizing Calculator and work down through the intermediate lines; the first figure that disagrees with your expectation is the one to investigate.
- Rerun Cable Sizing Calculator with the Current, Cable Length, and Max Voltage Drop rounded up, then rounded down — the spread is what a single figure hides.
The formula behind the result
If a term carries units, Cable Sizing Calculator shows where they cancel, and the figure inherits whatever unit survives the Engineering expression.
Worked example: with current of 20, cable length of 50, max voltage drop of 3, this cable sizing calculation returns Min area: 5.0 mm². The same run reports Max R = 0.3450 Ω | Drop ≤ 6.9 V.
The steps it follows:
- Max drop = 230 × 3% = 6.9 V
- Max resistance = 6.9/20 = 0.3450 Ω
- Copper ρ = 0.0172 Ω·mm²/m
- Area = ρ×L×2/R = 5.0 mm²
Understanding the result
Read the min area from Cable Sizing Calculator alongside the intermediate values — a step that looks off usually explains a headline that looks wrong.
Where it helps
Cable Sizing Calculator suits day-to-day planning, holding everything else equal while one value moves, and verifying a figure without opening a spreadsheet — the kind of question that arrives once a week and deserves a defensible number.
Common mistakes
Changing the Current, Cable Length, and Max Voltage Drop and assuming the rest rescaled is a frequent slip — every field on the cable sizing page is independent.
Tip: Cable Sizing Calculator returns Min area: 5.0 mm² at its defaults; double the Current (A) and it returns Min area: 10.0 mm².
Assumptions and limitations
The figure Cable Sizing Calculator reports is only as complete as the inputs: anything the page does not ask for sits outside the calculation.
Why use this calculator
Because Cable Sizing Calculator works the same on phone and desktop, keeps working offline after the first visit, and never asks for a sign-up.
Frequently Asked Questions
Which figure does cable sizing calculator produce?
At its core, Cable Sizing Calculator takes the Current, Cable Length, and Max Voltage Drop and evaluates the standard formula step by step, so the result can be checked rather than trusted on faith. Because a wrong answer is easy to catch: the steps on the cable sizing page show where a mistyped value entered the figure, which a bare result never reveals.
How is the min area calculated?
The first steps are max drop = 230 × 3% = 6.9 v, then max resistance = 6.9/20 = 0.3450 ω. The engine behind Cable Sizing Calculator evaluates the inputs in a single pass — no hidden iterations or adjustments — so the result you see is exactly what the formula produces for the values you entered.
What should I have ready for Cable Sizing Calculator?
Cable Sizing Calculator needs Current, Cable Length, and Max Voltage Drop and nothing else.
What if the Current (A) were twice as large?
At the defaults Cable Sizing Calculator returns Min area: 5.0 mm²; doubling Current (A) to 40 moves it to Min area: 10.0 mm².
What does the result from this tool tell you?
The main number the cable sizing calculator returns is the min area for your exact inputs. Cable Sizing Calculator returns a point estimate for the values shown and says nothing about how confident you should be in those values.
Where does the page fit in day-to-day work?
Common ground for Cable Sizing Calculator: day-to-day planning, holding everything else equal while one value moves, and verifying a figure without opening a spreadsheet, and any moment when a figure needs to be explained rather than announced. If the min area surprises you, change nothing and re-read the labels first; a unit mismatch is far more common than a wrong formula.
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