Savings calculator
Project savings growth after tax on interest and inflation, to see what the money is really worth.
About the savings calculator
Project savings growth after tax on interest and inflation, to see what the money is really worth.
Part of SmartCalcy’s investing & savings tools. It runs in your browser with no account, uses your own currency and units (change them at the top of the page), and gives estimates for information only, so check official guidance before you rely on a result.
How to use the savings calculator
What it calculates and when to use it
Projects how a savings account grows after tax on interest and shows what the balance is worth after inflation.
How to use it, step by step
- Enter your balance, monthly deposit, interest rate and years.
- Add the tax rate on interest, or leave it blank for a tax-free account.
- Enter expected inflation and read the nominal and real balance.
What each input means
- Interest rate (AER/APY) – The yearly rate after compounding.
- Tax on interest – Applied to the interest as it is earned.
- Inflation – Used to convert the balance into today’s money.
How to read the results
- Savings after tax – The final balance.
- In today’s money – The balance deflated by inflation.
- Real yearly return – Rate after tax and inflation.
The formula
Net rate = rate × (1 − tax). Monthly rate = (1 + net)^(1 ÷ 12) − 1. Balance = PV × (1 + m)^n + deposit × ((1 + m)^n − 1) ÷ m. Real return = (1 + net) ÷ (1 + inflation) − 1.
A worked example
5,000 plus 250 a month at 4.2% for 10 years with 2.5% inflation grows to 44,594 with 35,000 paid in. In today’s money that is 34,836, and the real return is 1.66%.
Assumptions and limits
- Rates stay fixed, which savings rates rarely do.
- Interest is taxed as earned, which simplifies allowances such as the UK Personal Savings Allowance.
Common mistakes
- Ignoring inflation when judging whether your savings are growing in real terms.
Frequently asked questions
What is AER?
The annual equivalent rate: the yearly rate including compounding. It is the same idea as APY in the US.
Related tools
Details
- Total deposits
- £35,000.00
- Interest after tax
- £9,593.56
- In today’s money
- £34,836.42after 2.5% inflation
- Real yearly return
- 1.66%after tax and inflation
Year by year
| Year | Deposits | Balance | In today’s money |
|---|---|---|---|
| 1 | £3,000 | £8,267 | £8,066 |
| 2 | £6,000 | £11,672 | £11,109 |
| 3 | £9,000 | £15,219 | £14,133 |
| 4 | £12,000 | £18,916 | £17,137 |
| 5 | £15,000 | £22,768 | £20,123 |
| 6 | £18,000 | £26,781 | £23,093 |
| 7 | £21,000 | £30,963 | £26,048 |
| 8 | £24,000 | £35,321 | £28,990 |
| 9 | £27,000 | £39,862 | £31,919 |
| 10 | £30,000 | £44,594 | £34,836 |