proportion calculadora — the short version

If you want a proportion calculadora without the sales pitch, the Proportion calculadora keeps the maths honest and the steps visible, the way a spreadsheet would if you'd built it yourself.

We built Proportion calculadora because the other tools for this job either cost a subscription or came with a consent banner the size of a small novel.

This is the kind of problem where a stray decimal costs you the mark. Think of one worked example you can reuse — then crunch the numbers and the rest of this page explains what the answer means.

Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

On this page you will see Proportion, Direct proportion and Inverse proportion treated as first-class terms — each one is linked to the calculators and references that use it, so you can follow the thread without retyping queries into a search bar.

If it helps, jump straight to the Maths hub or compare with the Ratio calculadora and the Rule of Three Calculator — those two calcs are the ones readers usually open right after this page.

From inputs to answer, in full

Consider a realistic scenario and follow it through:

Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

Scenarios where Proportion calculadora pays off

Proportion calculadora is aimed at people arriving with questions like these:

"Direct proportion"
"Inverse proportion"
"Solve proportion"
"Proportion formula"
"What is proportion"
"How to calculate proportion"

When it isn't the right tool

Every tool has an edge where it stops being the right answer. Proportion calculadora is no exception:

For legally binding tax or medical decisions — cross-check with HMRC, NHS or a qualified professional.
For very large or very small extremes the rounding error outgrows the useful precision.
When the underlying rate or threshold has changed since the page was last reviewed — always verify with the primary source.
When the input you have is already a derived figure (net of something) — feeding it in as "gross" will double-subtract.

Watch-outs before you trust the number

Every time you crunch the numbers for a new scenario, one of these creeps in — it's worth knowing them ahead of time.

Flipping the numerator and denominator — half the "wrong" answers on this type of calculation are an inverted ratio.
Not noticing that one input is already pre-rounded by the source that gave it to you.
Forgetting that negative inputs behave differently — the formula assumes positive magnitudes unless the tool says otherwise.
Running the calculation once and believing it. Always sanity-check against an order-of-magnitude estimate done in your head.
Copying numbers from a PDF and picking up hidden thousands separators as decimal points.

The sources behind the numbers

Where the maths needs an external authority, we cross-check against:

BBC Bitesize
MathsIsFun

Works well alongside

If this question keeps coming up for you, the same cluster of tools usually comes next:

Ratio calculadora — Simplify ratios, scale them up or down, and split a quantity in a given ratio — ideal for recipes, mixing fluids or sharing costs fairly.
Rule of Three Calculator — Solve a proportion by cross-multiplication — the classic rule-of-three used for recipe scaling, unit pricing and percent conversions.
Fraction calculadora — Add, subtract, multiply and divide fractions, convert decimals to fractions, and simplify to lowest terms — with each step shown clearly.
Percentage Calculator — Work out a percentage of a value, the percentage between two values, and percentage increases or decreases — with the formula shown.

How we keep this accurate

Our calculadoras run on pure, unit-tested functions — the same logic lives in the browser and in the CI test suite. When tax rates, thresholds or official figures move, the update lands within 24 hours of the announcement. You can read the editorial policy and corrections policy.

Found an out-of-date number on Proportion calculadora or anywhere else in the Maths toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.

Frequently asked questions

Direct proportion?

Practically speaking, feed the figures into the Proportion calculadora widget and it'll show the working. Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

Inverse proportion?

Here's the plain-English summary: open the Proportion calculadora widget at the top of the page. Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

Solve proportion?

In one line: this question usually arrives alongside Ratio calculadora, Rule of Three Calculator, Fraction calculadora. The Proportion calculadora handles the specific case above; the others cover adjacent ground.

Proportion formula?

Put simply, every figure is cross-checked against BBC Bitesize and the wider data. If you notice a stale rate, email the editorial desk and we'll patch it in under 24 hours.

What is proportion?

The direct take: yes, everything runs in your browser. No inputs are sent to our servers or any third party, nothing is logged and nothing persists after you close the tab.

How to calculate proportion?

Straightforward answer: Proportion calculadora is free to use, free to share and free to embed — pass the URL around a class, a slack channel or a family chat. The editorial policy covers attribution.

Proportion example?

Without the jargon, the short method: write the inputs in the units shown, run the calculation, then sense-check the answer against an order-of-magnitude estimate in your head.

Proportion worked example?

Tldr: if the result surprises you, run it a second time with slightly different inputs — small swings often reveal a unit or rounding issue in the original figures.

Proportion explained?

The useful way to think about it: a calculadora is a sanity check, not a verdict. For anything legally binding — contracts, tax filings, medical decisions — bring the figure to a qualified professional as a starting point.

Proportion definition?

Cutting to it, Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step. The page walks through the method in full so you can answer follow-up questions without guessing.

Proportion meaning?

Short answer: open the Proportion calculadora widget at the top of the page. Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

Proportion step by step?

Quick version: open the Proportion calculadora widget at the top of the page. Solve proportions of the form a/b = c/d for any missing term, with direct and inverse proportion worked through step by step.

How it works