Free tool
Website ROI Calculator: Estimate What Better Performance Is Worth
Seed Light built this free website ROI calculator so you can enter your own build cost. It shows how many months of extra gross profit a better converting website needs to pay for itself.
Enter a quoted build cost and see how many months of extra gross profit would cover it.
Your website, before and after
A rough number is fine. Google Analytics has it if you use it.
A call, a form, a WhatsApp message. Two is normal.
Be careful here. One extra point is a real result.
Your close rate. An estimate from your own records is fine.
One order or one job.
The margin left after the direct cost of delivering the product or service.
Put in the actual quote you were given. We do not fill this in for you.
Your result
Enter your numbers and your result will appear here. The calculation runs in your browser.
Book a free 15-minute call and we will help you read the numbers and decide what is worth improving first.
We record the result band you reach, not the numbers you enter.
Free to use, with no sign up. The calculation runs in your browser, so the values you enter are not sent to our server or stored.
The maths
How this calculator works
- 01
Two versions of the same month
Your visitors are held still. The tool runs them through your current contact rate, then through the rate you expect after the rebuild, and takes the difference.
- 02
Extra leads become extra sales
Those extra leads are multiplied by your close rate. The rebuild only changes how many people get in touch, so your sales process is left exactly as it is.
- 03
Extra sales become gross profit
Each extra sale is worth your average customer spend, then your gross margin is applied. What is left is the extra gross profit a month, which is the money a build can be paid back from.
- 04
The cost is divided by that
Your build cost divided by the extra gross profit each month is the payback in months. If the rebuild adds nothing, the tool says so rather than inventing a number.
A worked example
A clinic gets 1,500 visits a month, turns two in a hundred into calls, and closes three in ten. The rebuild is expected to reach three in a hundred, and 40 in every 100 of sales is gross profit. All money is shown in units so the shape stays clear. Example only. Replace these assumptions with your own numbers.
- Visitors a month
- 1,500
- Get in touch today
- 2 in 100, so 30 leads
- Get in touch after
- 3 in 100, so 45 leads
- Extra leads a month
- 15
- Extra sales a month
- 4.5, at a 30 in 100 close rate
- Extra revenue a month
- 9,000 units, at 2,000 units a sale
- Extra gross profit a month
- 3,600 units, at a 40 in 100 gross margin
- Build cost of 36,000 units
- Paid back in 10 months
Straight answers
Common questions
Common questions about the calculation and how to use the result.
Keep going
Other tools to try

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Open the toolLet’s talk
Ready to get more
customers?
Tell us what you want to grow or improve. We’ll reply within one working day with honest advice, even if we do not work together.
Prefer email or a call? hello@seed-light.com · +60 16-411 9138
Results so far
Results from real clients100+
Brands worked with
28,441+
Leads generated
$4.1M+
Sales generated for clients
Up to 13x
Return on Meta ad spend
Tallied from client ad accounts and store reports.
Monthly leads

