What does the lost client calculator work out?

What one lost client costs: their annual value multiplied by the years they would have stayed, plus the cost of winning a replacement.

What does the client concentration calculator show?

How much of your revenue sits with your five biggest clients, and how many ordinary clients it would take to replace one of them.

What does the growth calculator show?

How many clients you need to win in a year to grow by a chosen percentage once you account for the clients you lose, and how that number falls as you lose fewer.

What does the tax calculator show?

On 2026/27 UK rates, how much of a company's profit goes in corporation tax, National Insurance, income tax and dividend tax, and how much reaches the owner. Illustrative, not advice.

Calculators

Useful business calculators.

Four ways to put your own figures against the three things that decide how a business does. Illustrative, and not advice.

Calculator 1 What a lost client costs

What is one client walking away actually worth?

More than next month's invoice. It is every year they would have stayed, plus what it costs to find someone to replace them.

What a client is worth to you, a year £10,000

£1k £100k

More years they'd have stayed 3

1 10

What it costs you to win a replacement £2,000

£0 £25k

One client, worth £10,000 a year, leaves

Three more years they'd have stayed £30,000

Winning someone to replace them £2,000

What losing them cost £32,000

Illustrative. Put your own figures in.

Calculator 2 Client concentration

How much of your revenue sits with your five biggest clients?

A few clients usually matter far more than the rest. That's fine until one or more of them leaves. Set the two figures and see what the gap would look like.

Clients you have 40

6 150

Revenue share from your five biggest clients 60 %

5% 95%

5 clients bring in 60% The other 35 bring in 40%

12% of your revenue goes if one of the five leaves. One of your top five is worth about 11 of your other clients. That’s how many you’d need to win to get back to where you were.

Calculator 3 Clients you need to win to grow

How many clients do you need to win to grow?

Say you have 100 clients and want to grow by 10% this time next year. If you lose 25, the first 25 you win only get you back to 100.

Clients you have now 100

10 500

Client share you lose in a year 25 %

0% 50%

Growth you want this year 10 %

0% 50%

You will lose

25 clients this year, at that rate

So you need to win

35 25 to replace them, 10 to grow

Lose none, win 10, and the company grows by 10%. That’s 25 fewer sales than you need today.

Illustrative until you put your own figures in the sliders.

Calculator 4 What reaches you

How much of the profit actually reaches you?

The company pays corporation tax on the profit. If you draw dividends, you pay tax on that again.

Profit after all expenses are paid, before tax and before your own salary

Type an exact figure, or use the slider

£0 £1m £10m

What you pay yourself as salary

Type an exact figure, or use the slider

£0 £500,000

The rest of what you draw comes to you as dividends.

Profit

£200,000

→

Tax

£94,687

47% of the profit

→

What reaches you

£ 105,313

salary and dividends, after every tax

Yours Tax the company paid Tax you paid

See the full breakdown

Profit before tax £200,000

Salary £12,570

Income tax −£2,514

Employee National Insurance −£0

Employer National Insurance −£1,136

Corporation tax −£45,618

Dividends £140,676

Dividend tax −£45,420

Net to you £105,313

£45,420 is the tax on dividends, over and above what the company had already paid. Illustration only, on 2026/27 rates. Not advice. Whether money should stay in or come out depends on your circumstances and is a question for a qualified adviser.

Useful business calculators.

What is one client walking away actually worth?

How much of your revenue sits with your five biggest clients?

How many clients do you need to win to grow?

How much of the profit actually reaches you?

What are you doing to pay less tax ?

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