Financial scenario simulator
See how life's big decisions play out, before you make them.
Buy the house? Retire at 55? Take a year off? All of those, together?
ifso plays it out year by year, in plain English, with real tax, mortgage, and market math underneath, so you can see what each choice means before you make it.
Opens right in your browser with a sample plan ready to edit, with no account needed. No email, no credit card. Create an account only if you want to keep your plan.
Your biggest money questions don’t fit in a calculator.
The spreadsheet
You could build it yourself: amortization schedules, tax brackets, inflation adjustments, a tab per scenario… people do. It takes a weekend. Then a formula gets dragged one row too far, nothing errors, and every number from that row onwards is wrong.
And after all that work, the last row still doesn’t answer the question you opened it for: “so am I okay?”
One-off calculators
A mortgage calculator knows your payment. It doesn’t know your 401(k), your raise next year, or what buying the house does to retiring at 55. Every answer is an island.
Full planning suites
Built for advisors. All the depth is there, but you’re the one operating it: every input, every rebuild to compare two choices, every chart to interpret.
There’s a gap between “vibes and a spreadsheet” and $2,000 for a financial advisor. ifso lives in that gap.
What ifso can model
You say what you’d do. ifso works out what it means: the mortgage, the taxes, the ripple through every year after, and whether the money lasts. All of it in one connected model, and you can open any year to see the math.
Everything you own and owe
8 typesSavings and checking · Brokerage · 401(k) and IRA, Roth or traditional · Employer match · Your home · Your car · Any loans
The decisions you’re weighing
Buy or sell a home or car · Retire · Claim Social Security · Take a raise or a pay cut · Make a big one-time purchase
Taxes, done properly
Federal brackets · Payroll tax · Capital gains · State tax · Filing jointly · The home-sale exclusion · Contribution limits
Will the money last?
What you can safely spend · Bridging the years before 59½ · Which accounts to draw first · When to claim Social Security
The answer, in plain English
Does the money last, and to what age? · What can you actually spend? · If it falls short, when?
Compare two futures
ProTwo plans on one chart · The difference in dollars · Which one comes out ahead, and why
How likely is it to work?
Pro1,000 possible market futures · Your odds of success · The best and worst decades, not just the average one
From “what if” to an answer in three steps.
Tell it about your money
Age, income, accounts, the house, the car loan. Guided setup, plain questions, a few minutes. No bank passwords; ifso never connects to your accounts.
Add a decision to your timeline
Click an age. Buy a home, retire early, claim Social Security, add a kid’s expenses. One event, and ifso handles the mortgage amortization, the taxes on the down payment, the ripple effects through every year after.
At age 34...
…and a dozen more: sell the car, open an account, claim Social Security
Get the answer. Then compare.
The plan comes back as a sentence: “Funds retirement through age 90, spending $93k/yr.” Duplicate it, change one thing, and see both futures on the same chart with the difference in dollars.
Opens right in your browser with a sample plan ready to edit, with no account needed. No email, no credit card. Create an account only if you want to keep your plan.
Watch a plan come together.
A full walkthrough: build a plan, get the answer, then duplicate it and compare a second future side by side.
Spin up a fresh plan and name it. Here, it's “Retire at 65.”
One sentence tells you if the plan works.
At the top of every plan: does the money last, to what age, and what you can actually spend. If a plan falls short, ifso tells you when, “savings run out at 81,” so you know exactly what you’re fixing.
When you compare two plans, it tells you which one comes out ahead and why: a plan that keeps you funded beats one that ends with a bigger house but runs out of cash.
The same header, two different plans. One change can flip it.
You add one event. ifso does the rest.
Add “Buy a $450k home at 34” and ifso quietly does what a financial analyst would:
- Amortizes the mortgage month by month: principal, interest, property tax, insurance
- Pulls the down payment from your investments and pays the capital-gains tax on the way out
- Grows the home’s value, tracks your equity, and frees up cash flow when the loan ends
- Models the whole household: two incomes, married filing jointly, per-person 401(k) limits
- Re-runs your entire future (taxes, contributions, retirement) through age 90
You see one event on your timeline. ifso handles the hundreds of calculations behind it.
And not just the house: anything can change at any age, from raises and expenses to Social Security claimed anywhere from 62 to 70. Change one number, and every year after it recalculates: taxes, amortization, growth, withdrawals, and the answer up top.
“Probably fine” is not a plan. Get the odds.
Markets don’t return 7% every year. Run your plan through a Monte Carlo simulation, 1,000 market histories each drawing randomized year-by-year returns around your own growth assumptions, and get a straight answer: an 87% chance the money lasts. See the range of futures, great decade or terrible decade, not just the average one.
The full engine and one saved plan are free, forever. Pro adds unlimited plans, side-by-side Compare, and Monte Carlo odds for $69/year.
See it before you decide.
ifso is what you open at a real fork in the road: the house, the year off, the earlier retirement. Put in your real numbers, and in about ten minutes you’ll know what the choice actually costs.
Opens right in your browser with a sample plan ready to edit, with no account needed. No email, no credit card. Create an account only if you want to keep your plan.