GuacaFree tool
Savings goal calculator
Enter the goal you want to hit, what you already have saved and how many years you have, and the calculator tells you exactly how much to save per month — and how much of the journey growth covers for you. Free, and nothing to sign up for.
$
The amount you want to end up with.$
What you have already saved toward this goal.%
Effective annual rate (APY) of wherever the money sits. Use 0 for cash.How long you have to reach the goal.
All amounts above are in this currency.
Enter your savings goal and a horizon of at least one year to see how much you need to put away each month.
Assumes a constant rate compounded monthly and a flat monthly contribution. Estimates only — not financial advice.
Typing these numbers by hand? Guaca tracks them for you — accounts, investments and exchange rates update automatically, every day.
Start freeWhy start from the goal, not from what's left over
Most people save backwards: pay for the month first, then put away whatever is left. The problem is that nothing is ever left — expenses have a way of expanding to fill the space available. That is why the useful question is not “how much can I save?” but “how much do I need to save per month to get what I want?”: the house down payment, the emergency fund, next year’s trip, the car bought without a loan. When the goal leads, saving stops being a leftover and becomes one more fixed payment — except this one you pay to yourself.
That is exactly what this calculator does: it starts from the goal, the deadline and the rate, and solves for the monthly amount. The number it produces has real psychological power, because it turns a vague dream (“someday I’ll buy a place”) into a concrete instruction (“$702 every month, automatic transfer on payday”). If the number feels too big, do not abandon the goal: add years, trim the target or improve the rate, and watch it change. Playing with those three levers until you find a monthly amount you can actually sustain is, in practice, how you design a savings plan.
The rate changes how much you need to save
A round-number example you can verify above: you want $50,000 in 5 years, starting from zero. Under the mattress — a 0% rate — you need $833 a month: the goal divided by 60 months, with no help from anyone. But if that same money sits in an account earning 7% APY, the required amount drops to about $702 a month: you contribute roughly $42,100 and growth covers the other $7,900. The rate just handed you $130 of monthly budget back, every month, for five years.
Look at it the other way too: keep saving the full $833 a month at 7% and you do not land on $50,000 but on about $59,300 — more than $9,000 past the goal. That is the mechanics of compound interest pointed at a concrete goal: every contribution earns a return, and those returns earn returns. The longer the horizon, the more the rate carries and the less your wallet does — which is the mathematical reason to start this month instead of next year.
How much to save per month for the most common goals
Emergency fund: the classic recommendation is 3 to 6 months of expenses. It is a short-term goal, so use a modest rate (high-yield savings) and a 1 to 2 year horizon: here liquidity matters more than yield. House down payment: usually the biggest goal — often 10% to 20% of the price — with horizons of 3 to 8 years; this is where the rate helps you most, and where it is worth running the calculator with two or three scenarios. A trip or a big purchase: a small goal with a fixed date; the point is not the return but avoiding paying for it later on a credit card at 25% APR.
The structure is the same in every case: goal, deadline, rate, monthly amount. What changes is how aggressive you can be with the rate — short horizons call for stable products, long horizons tolerate funds that swing. If you have several goals at once, run each one separately in the calculator and add up the monthly amounts: seeing the total tells you immediately whether the plan fits your income or whether some goals need to be staggered in time.
How Guaca helps
This calculator gives you the plan; Guaca shows you whether you are keeping it. In the app you see all your accounts and savings in one place, with balances and exchange rates updating on their own, and your net worth recalculating every day — so you know without spreadsheets whether this month’s contribution actually landed and whether the snowball is growing on schedule. And when one goal starts feeling small, the FIRE calculator shows you the endgame: the day your returns pay your bills for you.
This calculator is an educational tool and is not investment advice.
Frequently asked questions
How much should I save per month?
The generic rules say 10% to 20% of your income, and the popular 50/30/20 rule earmarks 20% for savings and debt payoff. But those rules answer the question backwards: they tell you what you are 'supposed' to save, not what you actually need. This calculator's approach is to start from the goal — the down payment, the emergency fund, the trip — and let the math produce the exact monthly amount. If that number is below your 20%, you have slack; if it is above, you have three levers: a longer deadline, a smaller goal or a better rate. What matters most is that the amount comes from a plan rather than from whatever is left at the end of the month, because at the end of the month there is rarely anything left.
What rate should I enter — APY or APR?
Enter an effective annual rate, which is what APY (annual percentage yield) measures — the real yearly growth after compounding is accounted for. If the money will sit in a regular checking account, be honest and enter something near 0%; a high-yield savings account has hovered around 4–5% APY in recent years, and a CD gives you a fixed rate you know in advance. For long-horizon goals invested in index funds there is no advertised rate; 7% nominal is a common long-run estimate for a diversified portfolio, but run a conservative scenario too, because no future return is guaranteed. And remember inflation eats part of the yield: a 5% rate with 3% inflation moves you toward the goal in dollars, but those dollars will buy less.
What if I can't afford the monthly amount the calculator shows?
You have three levers, and it pays to pull them in this order. First the deadline: it is the most powerful and cheapest lever, because every extra year both spreads the goal over more months and gives compounding more time to help — try moving from 3 to 5 years in the calculator and watch the required amount drop. Second the goal itself: sometimes the down payment can be slightly smaller or the trip slightly leaner without breaking the plan. Third the rate, but carefully: chasing higher returns means taking more risk, and a short-term goal should never depend on the market having a good year. What does not work is giving up and saving 'whatever you can': a small automatic contribution beats a large occasional one almost every time.
Where should I keep the money for a savings goal?
It depends almost entirely on the deadline. For goals under 2 years — the trip, the car down payment, the emergency fund — prioritize liquidity and stability: a high-yield savings account, a CD maturing near your date, or a money market fund; a market dip three months before the deadline can wipe out years of discipline. For goals 5 or more years out you can accept more volatility in exchange for higher expected growth, with diversified index funds or ETFs. The classic trap is the reverse: short-term money in stocks 'so it grows', or long-term money in a 0% account 'to be safe'. This page is educational and is not investment advice — for big decisions, consider talking to a professional.
Does the calculator account for inflation?
Not directly: the goal and the monthly amount are computed in nominal dollars, with no inflation adjustment. For short goals — 1 or 2 years — that barely matters, because inflation cannot move the target much. For long goals it does: a down payment that costs $50,000 today may cost noticeably more in 8 years. You have two ways to handle it: inflate the goal yourself (estimate what the goal will cost on the target date and use that number), or enter a real rate — your APY minus expected inflation — and read the result in today's money. The second is more elegant; the first is easier to explain at the dinner table.
Track this automatically with Guaca
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