Interactive finance tools you can drag
Things you can drag. Each one runs in your browser, works on a phone, and is free to embed on your own site with a link back. An AI assistant can quote a formula. It cannot drag a rate.
Start by dragging something
Growth and time
Compound growth curve you can drag
Drag the balance curve to set the annual return and watch the gap open between the money you paid in and the interest that compounding added on top.
How your savings rate sets the timeline
Drag the savings rate and watch the years of saving fall. The curve is steep at low rates, so the first few points added are worth far more than the last few.
What inflation does to buying power
Drag an inflation rate and a savings rate to watch buying power fall. Shows the share of today's buying power left each year and how long it takes to lose half.
What a yearly fee costs over decades
Drag the fee up and watch two growth curves separate. A 1 percent yearly fee is not a 1 percent cost: over 30 years it takes close to a fifth of the ending balance.
Invest all at once or spread it out?
Drag the market trend and the buying window to see which path finishes ahead. A rising market favours investing at once, a falling one favours spreading the same sum.
Why the order of returns matters
Drag ten fixed yearly returns from worst first to best first. Take nothing out and the ending balance never moves. Take a fixed sum out and the order decides it.
Debt
Debt snowball vs avalanche simulator
Drag the total monthly payment and compare two payoff curves, highest rate first against smallest balance first. Shows months to debt free and what each order costs.
Extra payment curve you can drag
Drag extra monthly principal on a fixed loan and watch months remaining and interest saved. The curve flattens: the first extra dollars cut more time than the later ones.
Amortisation explorer: drag the rate
Drag a rate up or down and watch every loan payment split into interest and principal. Marks the payment where principal first overtakes interest.
Credit utilization: drag the balance
Drag a reported balance against a total credit limit to see utilisation as a percentage and the band it falls in, with the direction of effect rather than a score.
Investing
Risk against return scatter plot
Drag a portfolio point along the curve between two assets and watch expected return move in a straight line while risk does not. Illustrative teaching values, plotted.
How diversification cuts portfolio risk
Drag the correlation and the number of holdings to watch portfolio risk fall towards a floor. Shows the risk diversification removes and the shared risk it cannot.
How a stock and bond mix shifts with age
Drag a glide path to see stock and bond shares change with age, read the mix at any age, and watch an illustrative risk level move with it.
Bond price against the market rate
Drag along the price-yield curve to set the market rate and watch the bond price move the other way. Par, premium and discount are marked, and longer maturity tips the curve steeper.
Yield curve shapes: drag the curve
Drag a control point at each maturity to build a yield curve and see it named normal, flat, inverted or humped, with what each shape is usually read as.
Household planning
Budget allocation explorer
Drag five spending bands to see where take-home pay goes. Each band is a share of take-home, the five plus the unassigned remainder always total 100 percent, and the saving rate is the headline.
Rent against buy: the break-even year
Drag the horizon and watch rent paid so far meet the cost of owning, counting interest, tax, upkeep and the cost of buying and selling. Illustrative figures.
Retirement projection you can drag
Drag the monthly contribution and the expected return, and watch a retirement balance redraw with a fan showing the same plan 2 points either side of your rate.
Employer match curve you can drag
Drag the share of pay you defer and watch the employer match rise until the cap, then go flat. Past the cap, extra deferral is your money alone.
Marginal against effective tax rate
Drag an income marker across illustrative tax bands to see the rate on the next dollar, the effective rate on the whole income, and why a raise still lifts take-home pay.