Savings Goal Calculator — How Much to Save Each Month
Free savings-goal calculator — set a target amount and a time horizon, get the monthly contribution you need at any interest rate. Accounts for an initial deposit.
Enter the amount you want to have saved, the time horizon, the annual interest rate you expect, and (optionally) how much you’ve already put aside. The calculator returns the monthly contribution you need.
The math
PMT = (FV − PV(1 + r)ⁿ) · r ÷ ((1 + r)ⁿ − 1)
Where:
- FV = future value (your goal)
- PV = present value (initial deposit)
- r = monthly interest rate (annual ÷ 12, expressed as a decimal)
- n = number of months (years × 12)
The initial deposit grows on its own — by month n it’s worth PV(1 + r)ⁿ — so the monthly contributions only have to cover the remaining gap. At a zero rate the whole thing collapses to (goal − initial) ÷ months.
Why time matters more than rate
For most reasonable horizons, another five years of saving moves the needle more than another percentage point of return. A $100,000 goal at 6%:
| Horizon | Monthly contribution |
|---|---|
| 5 years | $1,433.27 |
| 10 years | $610.21 |
| 20 years | $216.43 |
| 30 years | $99.55 |
Compounding eats most of the work after about year 10. The practical implication: start small, start now. Doubling your monthly contribution later helps less than starting a few years earlier.
Real vs nominal
Two ways to think about a $100,000 goal in 30 years:
- Nominal: literally a hundred thousand future dollars. Use the nominal interest rate (say 7%).
- Real / inflation-adjusted: a hundred thousand of today’s dollars’ worth of purchasing power. Use the real rate (nominal minus inflation, say 4%). The monthly contribution rises, but the dollar amount you’re aiming at will mean what you expect.
Pick one and stay consistent. Mixing nominal goals with real rates (or vice versa) is the most common source of “why is my retirement number so off” surprises.
Worked examples
-
$50,000 in 10 years at 6%, starting from zero
Save $305.10/month for 10 years to reach $50,000.00 — $36,612.30 contributed, $13,387.70 from interest.
-
$50,000 in 10 years at 6%, with $10,000 already saved
Save $194.08/month for 10 years to reach $50,000.00 — $33,289.84 contributed, $16,710.16 from interest.
-
Zero-rate (cash under the mattress): $10,000 in 5 years
Save $166.67/month for 5 years to reach $10,000.00 — $10,000.00 contributed, $0.00 from interest.
Frequently asked questions
What interest rate should I use?
For a **high-yield savings account / money market**, use the current account rate (typically 3–5% in 2026 in the US). For a **brokerage / retirement account invested in a broad index fund**, a long-term planning rate of 5–7% real (after inflation) is the conventional assumption. For **cash you actually keep in cash**, use 0. The calculator doesn't care which — it just runs the math on whatever you enter, so you can sanity-check both pessimistic and optimistic scenarios.
Does this account for inflation?
No — the calculator works in nominal dollars. If you want the goal expressed in *today's* dollars, subtract expected inflation from the interest rate before entering it (e.g. 7% nominal, 3% inflation → enter 4% real). That gives you the contribution needed to hit a goal whose purchasing power matches today's.
What about taxes?
Interest earned in a taxable account is generally taxed each year; in a tax-advantaged account (US: 401(k), IRA, Roth IRA, HSA; Brazil: previdência privada, alguns CDBs/LCIs) the tax treatment is different. For simplicity the calculator assumes the rate you enter is the *net* growth rate. If you're using it for a regular brokerage account, knock the rate down a bit to roughly approximate after-tax returns.
How does the initial deposit help?
Money you already have starts compounding immediately. With 10 years at 6%, every $1,000 you start with grows to about $1,819 by the end — so each dollar of starting capital does the work of roughly $1.82 of future contributions. That's why the calculator subtracts the *future value* of your initial deposit from the goal, not just the deposit amount.
Why does the calculator say my deposit already meets the goal?
When your initial deposit (compounded forward at the rate you entered) ends up at or above the goal, no monthly contribution is needed — the existing balance plus interest gets you there. Either your goal is modest relative to what you've already saved, or your assumed rate is high. Worth double-checking the rate.