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FinToolSuite
Updated May 14, 2026 · Planning · Educational use only ·

Will Planning Calculator

What a will really costs.

Calculate will planning cost — solicitor versus DIY comparison — to weigh the savings against the risk of getting it wrong.

What this tool does

This tool calculates and compares the total cost of creating a will through a solicitor versus preparing one yourself. It takes your solicitor fees, DIY costs, and an estimate of how complex your estate is, then spreads these expenses across the years your will remains valid. The result shows the annualised cost for each approach and the difference between them. Solicitor costs are adjusted by your complexity factor—more intricate estates typically involve higher fees—while DIY costs remain static. This comparison helps illustrate the cost structure of both methods over time. The calculation assumes your will remains valid for the period you specify and doesn't account for future updates, legal challenges, or changes in fee structures.

Enter Values

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Formula Used
Solicitor cost
Complexity factor

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Calculations or display — let us know.

Disclaimer

Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.

Making a will costs 150-500 for basic solicitor service, 30-90 for DIY online services. For simple estates, DIY is usually fine. Complex estates (business ownership, trusts, multiple properties) benefit from solicitor guidance despite higher cost.

400 solicitor will lasting 10 years amortises to 40/year. DIY 60 lasting 10 years = 6/year. The 340 upfront gap represents peace of mind and reduced error risk. This calculator shows both sides.

Review wills every 5-7 years or after major life events (marriage, divorce, birth, significant inheritance). Letting a will become outdated causes more problems than any saving from the DIY route.

A worked example

Try the defaults: solicitor will cost of 400, diy will cost of 60, complexity factor of 1, years will is valid of 10. The tool returns 400.00. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Solicitor Will Cost, DIY Will Cost, Complexity Factor, and Years Will Is Valid. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

The formula behind this

Solicitor lifetime = cost × complexity. Annualised = lifetime / years. Difference vs DIY shown. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

The annual review habit

Plug new numbers in every year. Income changes, expenses shift, markets move. A plan that isn't revisited quietly drifts out of date. This tool is cheap to re-run — so re-run it.

What this doesn't capture

Real plans get re-run against new information every year or two. The result here is a reasonable direction, not a destination. It is a starting point for thinking, not a commitment to a specific future.

Example Scenario

Solicitor ££400 × 1x vs DIY ££60 = 400.00.

Inputs

Solicitor Will Cost:£400
DIY Will Cost:£60
Complexity Factor:1
Years Will Is Valid:10 years
Expected Result400.00

This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.

Sources & Methodology

Methodology

Solicitor lifetime = cost × complexity. Annualised = lifetime / years. Difference vs DIY shown.

Frequently Asked Questions

When does DIY not work?
Businesses to pass, multiple properties, trusts for minor children, complex family arrangements (step-children, unmarried partners), significant assets overseas. Any of these makes solicitor advice worthwhile.
What does the complexity factor actually represent?
The complexity factor is a multiplier that reflects how much more involved a solicitor's work becomes when an estate includes things like business interests, multiple beneficiaries, or overseas assets. A factor of 1 represents a straightforward estate, while higher values scale the solicitor cost upward to approximate the additional time and expertise typically involved. DIY costs are unaffected because template-based tools don't adjust for complexity in the same way.
Why does the calculator spread costs across years?
Annualising the cost puts both approaches on a comparable footing, since a will is a long-term document rather than a one-off transaction. Dividing the total spend by the number of years the will is expected to remain valid shows what each method effectively costs per year of coverage. This framing makes it easier to weigh a higher upfront solicitor fee against a lower DIY cost when both are viewed over the same time horizon.
How do I estimate how long my will remains valid?
A will generally stays legally valid until it is revoked, replaced, or invalidated by a life event such as marriage or divorce, so there is no fixed expiry date. For this calculator, the years field represents the period over which you expect the current will to remain in use before a significant update would be needed. Common assumptions range from five to fifteen years, though major life changes often prompt revisions sooner.

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