Find a calculator for your question
Explore the tools available today. Each calculator explains its inputs, assumptions, and limits so you can compare scenarios using your own numbers.
Assets and cash reserves
Emergency fund calculator
Estimate a cash target and time to fill the gap using your chosen expense coverage. No interest or reserve recommendation.
Net Worth Calculator
Add your asset values and debts to calculate net worth, including a negative balance. No account connections, valuations or saved records.
Saving and investment growth
Compare starting now or later
Compare the same budget and end date, holding savings as zero-interest cash during a delay. Fixed assumptions, not timing advice.
Portfolio Rebalancing Calculator
Calculate buys, sells or new-cash allocations for your own target weights. No allocation recommendations, taxes or trading.
Investment fee calculator
Compare two annual percentage fee assumptions with a zero-fee baseline. Separate direct deductions from the later compounding difference; no actual fund fees or recommendations.
Savings goal calculator
Solve for a month-end contribution to a future nominal target. Uses your fixed return assumption; no budget or product recommendations.
Savings and HYSA calculator
Explore balances, hypothetical interest, and purchasing power using your own APY. No live bank rates, account recommendations, or insurance claims.
S&P 500 investment calculator
Explore future value or solve for starting amount, return rate, or investment length. Uses fixed assumptions, not market predictions.
$10,000 invested in the S&P 500
Explore a $10,000 starting investment with editable assumptions. Historical returns do not determine future results.
$100,000 invested in the S&P 500
Compare growth and purchasing power for a larger starting amount. Fee examples are separate from the calculator.
$500,000 invested in the S&P 500
Model growth, time horizons, and purchasing power for a $500,000 lump sum. Fixed assumptions, not predictions.
Monthly S&P 500 investment calculator
Explore recurring contributions and see how much comes from your money versus hypothetical growth. No taxes or fees are included.
S&P 500 weekly investment calculator
Model $100 weekly and $200 biweekly contributions under an equal $5,200 annual budget with inflation adjustments.
S&P 500 compound interest calculator
Explore how compounding works on a lump sum versus recurring monthly contributions in the S&P 500.
S&P 500 million dollar calculator
Calculate how many years it takes to reach a $1,000,000 portfolio based on your starting capital and monthly contributions.
S&P 500 10-year scenario calculator
Compare a fixed 10-year scenario and adjust its assumptions. This does not forecast the next ten years.
S&P 500 30-year scenario calculator
Compare a 30-year timeline with starting principal, recurring monthly contributions, and inflation.
S&P 500 calculator with GBP display
Use pounds for display only. No currency conversion, UK tax, ISA, or SIPP rules are included.
Loans and uses of money
Pay off debt or invest calculator
Compare extra payments and investments with the same monthly budget and end date. Fixed rates only; no taxes, liquidity assessment, or route recommendation.
Loan calculator with extra payments
Calculate fixed-rate monthly payments, payoff time, and interest with an amortization table. No fees, variable rates, or lender quotes.
Retirement and housing scenarios
Coast FIRE calculator
Work backward to a current investment threshold from your spending and target-conversion assumptions, with no further contributions. No withdrawal simulation or retirement guarantee.
Retirement savings calculator
Compare accumulation at your chosen retirement age with your own target. Fixed assumptions only; no withdrawals or retirement success probability.
Rent vs buy calculator
Compare housing and investments under equal initial cash and monthly budgets. Assumes fixed parameters and a final home sale; no tax deductions or housing advice.
Understand the assumptions
Each tool explains its calculation model and limitations. Results depend on the assumptions you supply and are not financial advice.