How it works
What this calculadora actually does
The ROI calculadora works out your roi calculadora in seconds, using the 2026 figures most UK households actually check against.
Most Business tools bury the calculation. ROI calculadora shows it. Punch in your figures, read the working, share the URL if you need a second opinion.
Rules of thumb lie at scale — the arithmetic holds up to a whiteboard argument. Decide whether you want gross or net, and commit — then model the numbers and the rest of this page explains what the answer means.
Work out ROI on any project, campaign or investment — net return divided by cost, with annualised and cumulative views.
On this page you will see Return on investment and ROI 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 Business hub or compare with the Break-Even calculadora and the Payback Period calculadora — those two calcs are the ones readers usually open right after this page.
Following the method end to end
Here's what happens when you plug real numbers in.
Work out ROI on any project, campaign or investment — net return divided by cost, with annualised and cumulative views.
Scenarios where ROI calculadora pays off
ROI calculadora is aimed at people arriving with questions like these:
- "ROI formula"
- "Marketing ROI"
- "Annualised ROI"
- "What is roi"
- "How to calculate roi"
- "Roi formula"
When it isn't the right tool
Every tool has an edge where it stops being the right answer. ROI 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.
The snags that cost people the answer
Every time you model 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:
- Harvard Business Review
- Sebrae
Works well alongside
If this question keeps coming up for you, the same cluster of tools usually comes next:
- Break-Even calculadora — Work out how many units or how much revenue covers fixed and variable costs for a product or service.
- Payback Period calculadora — Compute simple and discounted payback period in months from upfront cost and recurring cash flows.
- Gross Margin calculadora — Work out gross margin and gross-margin percentage from revenue and COGS, with category benchmarks for SaaS, retail and services.
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 ROI calculadora or anywhere else in the Business toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.