Calculator
What the Real Return Calculator does
Real Return Calculator: calculates Real Return % and Nominal − Inflation from Nominal Return % and Inflation %. Example: nominal return % 12 and inflation % 6 gives real return % 5.66%.
The Real Return Calculator takes Nominal Return % and Inflation % and returns Real Return % and Nominal − Inflation. You can nudge a single number and watch the effect straight away.
Most people who open the Real Return Calculator are savers modelling a goal. Getting the arithmetic right before you sign is cheaper than discovering it afterwards.
Nothing about your finances is transmitted or logged. The arithmetic happens on your own device.
Further down the page: what each field expects, how the result is derived, and one example worked from the defaults.
What do the Real Return Calculator fields mean?
The Real Return Calculator uses 2 inputs. Pre-filled inputs double as documentation: each one shows what a reasonable value looks like.
| Field | What to enter | Default |
|---|---|---|
| Nominal Return % | accepts -50 to 50 | 12 |
| Inflation % | accepts -20 to 50 | 6 |
How does the Real Return Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
The guard clauses run before the formula does, which is why mistakes surface next to the field.
Worked example
These are the values the Real Return Calculator loads by default, and the result it produces from them. This is the worked example the page starts from, reproduced here so you can check the arithmetic.
| Nominal Return % | 12 |
|---|---|
| Inflation % | 6 |
| Real Return % | 5.66% |
|---|---|
| Nominal − Inflation | 6.00% |
Read next: Compound vs Simple Interest: Where the Difference Comes From
How to use it
- Put Nominal Return % (-50 to 50).
- Key in Inflation % (-20 to 50).
- The output refreshes live, so you can stop as soon as the number looks right.
- The results panel then shows Real Return % and Nominal − Inflation.
- Copy Link puts the current inputs in the URL, so bookmarking it brings the same numbers back.
What this tool does not do
- Lender rounding rules differ, so the final figure on your statement may differ by a small amount.
- Rates are treated as fixed for the whole term; a floating rate will change the outcome.
- Assumptions built into the method are stated above, but they are still assumptions.
- Check that each figure is in the unit the label asks for; that is the most common source of a wrong result.
Frequently asked questions
Nominal Return % and Inflation %. That is the whole form. Every box already holds a working value, which makes it easy to isolate the effect of a single variable.
Nominal Return % accepts -50 to 50. Values outside that range are rejected with a message naming the field, rather than producing something that looks valid but is not.
With the values loaded when the page opens, real return % comes out as 5.66%. The figure is derived from the inputs above, so it updates whenever they do.
Nothing leaves your machine. The only network traffic is loading the page itself.
No. There is no account, no usage cap and no trial period. The site is funded by advertising rather than by charging for the tools.
The result is reliable for the assumptions you entered, and those assumptions are the fragile part. A rate that changes mid-term will move the outcome more than any rounding here.