compound
Savings Goal Calculator — 3-Unknown Solver
The Savings Goal Calculator solves backwards for any one of three unknowns: given a target (e.g. $100,000), specify any two of {starting amount, monthly contribution, time} and we'll solve the third exactly. Use it for down payments, emergency funds, college savings, or any long-term goal.
Updated:
How to use
- Pick the unknown. Monthly contribution, time, or starting amount.
- Enter the other two. Plus the target and assumed annual rate.
- Read the result. We show the value you need to reach the goal.
Key features
Solve for contribution
Have target + start + time → required monthly?
Solve for time
Have target + start + monthly → how long?
Solve for start
Have target + monthly + time → starting amount needed?
Monthly compounding
Standard FV formula — not an approximation.
Contributed vs interest
Shown separately to clarify growth composition.
8 currencies
USD, EUR, GBP, SGD, INR, AUD, CAD, VND.
Why Treasury.to?
- ✓3 different solver modes
- ✓Closed-form + bisection
- ✓Multi-currency
- ✓Instant
- ✓Free
- ✓Mobile-first
Frequently asked questions
Is the solver penny-accurate?
Yes — contribution and start modes use the closed-form FV annuity formula. The time solver uses 200-iteration bisection accurate to under 0.05 months.
What compounding does it use?
Monthly by default, matching savings accounts and ETF DCA. For other frequencies, use the Compound Interest Calculator.
Can I model irregular contributions?
Not here — this tool assumes a constant monthly amount. Use the Compound Interest Calculator with 'both deposits & withdrawals' for irregular flows.