Looking for a developer to build a pension savings calculator for a financial advisor site

I run a small financial consulting practice and want to add an interactive calculator to my website that helps visitors estimate how their retirement savings could grow over time. The tool should let a visitor enter their current age, a planned monthly contribution and an expected annual rate of return, then calculate the projected capital available at retirement age. Results need to be presented clearly, ideally with a chart that shows how the balance grows year by year, so a non-technical visitor immediately sees the effect of compounding and why starting early matters.

The calculator will sit on an existing website, so it needs to fit the current design and work well on both desktop and mobile. Correct financial math (compound interest, adjustable retirement age, maybe an inflation option) matters as much as the visual side. The chart is meant to be the centerpiece that convinces a visitor to book a consultation, not just a decorative widget. Clean, commented code I can hand to another developer later is a plus.

What I expect from the freelancer:
— a working interactive calculator with input validation
— an animated or at least responsive growth chart
— a short written explanation of the calculation method
— mobile-friendly layout matching the existing site style
— basic testing across major browsers