Financie

Kalkulačka ISA

ISA Calculator (Stocks & Shares)

Monthly contribution (£)

Ročný výnos

Years to invest

Existing ISA balance (£)

What is ISA Calculator?

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An ISA (Individual Savings Account) is a tax-free wrapper for savings and investments. Any growth, interest, or dividends earned within an ISA are completely free from Income Tax and Capital Gains Tax — forever. The annual allowance is £20,000 per person (2024/25). Unused allowance cannot be carried forward.

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f(x)Compound growth formula: FV = PV × (1+r)^n + PMT × ((1+r)^n − 1)/r

Variable Legend

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Symbol	Meno	Jednotka	Popis
FV	PV × (1+r)^n + PMT × ((1+r)^n − 1)/r	—	PV × (1+r)^n + PMT × ((1+r)^n − 1)/r
PV	PV value	—	Variable used in the calculation
PMT	PMT value	—	Variable used in the calculation

How to ISA Calculator

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1Contribute up to £20,000 per tax year (April 6 – April 5)
2Stocks and Shares ISA: invest in funds, shares, ETFs — suitable for 5+ year horizons
3Cash ISA: earn interest tax-free — better than regular savings account for higher-rate taxpayers
4Lifetime ISA (LISA): 25% government bonus on up to £4,000/year — for first home or retirement
5Compound growth formula: FV = PV × (1+r)^n + PMT × ((1+r)^n − 1)/r

Worked Examples

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Example 1

Given:£500/month for 20 years at 7% return

Výsledok:~£248,000 projected

£120,000 contributed, £128,000 tax-free growth

Example 2

Given:£20,000 lump sum for 30 years at 7%

Výsledok:~£152,000

All gains completely tax-free

Real-World Applications

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Personal financial planning and budget setting

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Comparing loan options before signing agreements

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Understanding the true cost of borrowing over time

ISA Types 2024/25

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ISA Type	Annual Limit	Tax on Growth	Best For
Cash ISA	£20,000	None	Short-term savings, high earners
Stocks & Shares ISA	£20,000	None	Long-term wealth building
Lifetime ISA	£4,000	None + 25% bonus	First home / retirement (under 40)
Innovative Finance ISA	£20,000	None	Peer-to-peer lending (higher risk)
Junior ISA	£9,000	None	Saving for children

Frequently Asked Questions

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What is Isa?

How accurate is the Isa calculator?

The calculator uses the standard published formula for isa. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Isa calculator use?

This calculator works with inches, British pounds, percentages. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Isa calculator use?

The calculator applies the standard formula for this type of calculation. See the 'How It Works' steps above for the detailed formula breakdown.

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Pro Tip

The Lifetime ISA (LISA) bonus of 25% on contributions up to £4,000 = £1,000 free per year. However, withdrawing for any reason other than first home purchase or retirement (age 60+) incurs a 25% government withdrawal charge — effectively a loss.

References

Len na informačné účely. Tento nástroj nepredstavuje finančné poradenstvo. Pred investičnými alebo finančnými rozhodnutiami sa poraďte s kvalifikovaným finančným poradcom.

Deep Dive

Read the full guide on how to use this calculator effectively

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Accuracy-checked

Reviewed October 2026

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