Calculator workbench
Financial ideas, made measurable
Start with what is left each month, assign the next dollar a job, then let time and uncertainty onto the page. Every projection exposes its assumptions.
Desk index
11 instruments
4 decision stages
0 uploads
01
Establish the base
Give the next dollar a job before giving it a return assumption.
Tool 01 · 3 minutes
What's left over each month
How much can I actually put to work?
- You'll need
- Take-home pay and your recurring monthly costs
- You'll see
- One monthly figure that the debt and savings calculators can use as a starting point
Working sketchINPUT → RESULTInflow is divided among obligations, minimums, and room still available. $1,350 remains after obligations in the illustration.
Tool 02 · 3 minutes
Account purpose guide
What job should the next dollar be assigned before choosing a product?
- You'll need
- What the money is for, when it may be needed, and whether the balance can fall
- You'll see
- A purpose-first route and the trade-offs to verify before opening or funding an account
Working sketchINPUT → RESULTMoney moves through obligations, reserves, near-term goals, and long-term growth. Current · reserve · near-term · long-term.
02
Choose the next use
Debt, a dated goal, and liquid reserves compete for the same monthly room.
Tool 03 · 4 minutes
Debt or investing
Should the extra money pay down debt, or get invested?
- You'll need
- A balance, its interest rate, and the minimum payment
- You'll see
- The return where the two paths tie — so you can judge the risk instead of guessing at it
Working sketchINPUT → RESULTDebt payoff and hypothetical investment paths meet at a break-even return. The debt rate becomes the guaranteed side of the comparison.
Tool 04 · 5 minutes
Which debt to clear first
What order should I pay these off in?
- You'll need
- Each balance, its rate, and its minimum payment
- You'll see
- What highest-rate-first actually saves against smallest-balance-first, in interest and in months
Working sketchINPUT → RESULTBalances collapse in sequence as each cleared payment rolls to the next. Three balances collapse as each cleared payment rolls forward.
Tool 05 · 2 minutes
Reaching a savings goal
How much a month, or how long?
- You'll need
- A target amount and either a deadline or a monthly amount
- You'll see
- A monthly figure and a date, and how much of it is growth
Working sketchINPUT → RESULTMonthly deposits stack beneath a modeled growth curve toward a marked target. $15k after three years in the illustration.
Tool 06 · 4 minutes
Cash or market?
Which job does this money need to do before return enters the question?
- You'll need
- An amount, monthly deposit, time horizon, savings APY, and hypothetical return
- You'll see
- Two projections beside the liquidity, certainty, and loss-risk trade-offs that the balances omit
Working sketchINPUT → RESULTCash certainty, savings interest, and a hypothetical market path share one horizon. $63k savings · $70k hypothetical market.
03
See what time changes
Separate deposits from growth, mark the first milestones, and price ongoing costs.
Tool 07 · 3 minutes
Compound growth explorer
What can time, deposits, and an assumed return build together?
- You'll need
- A starting amount, monthly deposit, horizon, and assumed return
- You'll see
- Deposits, growth, and inflation-adjusted purchasing power on one measured timeline
Working sketchINPUT → RESULTDeposits build the base; modeled growth gradually occupies more of the balance. $292k modeled total; $130k deposited.
Tool 08 · 2 minutes
The first $100,000
When does growth begin doing more of the work?
- You'll need
- A starting amount, monthly deposit, and hypothetical return
- You'll see
- A milestone ledger showing the month, deposits, and modeled growth at each mark
Working sketchINPUT → RESULTEach $25,000 mark records the changing share built by deposits and growth. $100k is modeled in 8y 4m.
Tool 09 · 3 minutes
Fee drag
What does a small ongoing fee remove over a long horizon?
- You'll need
- A balance, monthly deposit, horizon, gross assumed return, and annual fee
- You'll see
- Fees paid, growth lost, and the full difference in ending value
Working sketchINPUT → RESULTTwo nearly identical paths separate as ongoing costs compound through time. $152k modeled gap from a 1% ongoing fee.
04
Test a larger decision
Housing and cards hide costs in different places; put all of them on the page.
Tool 10 · 6 minutes
Renting against buying
Am I better off buying, or renting and investing the difference?
- You'll need
- A price, a rent, and the rates you'd expect
- You'll see
- Which assumption the answer actually turns on — usually appreciation, not the monthly payment
Working sketchINPUT → RESULTTwo net-worth paths move through the assumptions that separate them. Two net-worth paths expose the assumption separating them.
Tool 11 · 4 minutes
Which card is worth carrying
Is a rewards card actually worth it for how I pay?
- You'll need
- Roughly what you spend where, and whether you carry a balance
- You'll see
- Why carrying a balance outweighs almost any reward, and what a card is worth after fees
Working sketchINPUT → RESULTRewards flow in while annual fees and carried-balance interest flow out. $445 illustrative rewards after the annual fee—before interest.