DocomintSparzielrechner
Berechne, wie viele Monate es dauert, ein Sparziel mit regelmäßigen Einzahlungen zu erreichen.
What is a Sparzielrechner?
Works backward from a target — a down payment, an emergency fund, a trip — to tell you how long regular monthly contributions will take to get there, optionally factoring in interest on the growing balance (a high-yield savings account earns a bit extra along the way, which shortens the timeline slightly).
How to use the Sparzielrechner
- Enter your goal amount, current savings, monthly contribution, and an optional interest rate
- Press Calculate
- The number of months to reach the goal appears instantly, simulated on your device
Formula
Balance(this month) = Balance(last month) × (1 + monthly rate) + Contribution, simulated month by month until Balance ≥ Goal
A starting balance plus recurring contributions plus compounding doesn't reduce to one clean formula, so this simulates the balance growing month by month instead.
Example
Starting from $1,000 with a $300/month contribution at 2% annual interest, reaching a $10,000 goal takes 30 months (2 years, 6 months) — dropping the interest rate to 0% barely changes that timeline, since the effect is small over a relatively short 2.5-year span.
Common mistakes
- Expecting an instant closed-form answer the way Compound Interest Calculator gives one — a starting balance plus ongoing contributions genuinely needs simulation, not a single formula.
- Setting both monthly contribution and interest rate to 0, which makes the goal mathematically unreachable (the balance would never move).
- Not accounting for taxes on any interest earned along the way, which this doesn't factor into the projected balance.
Frequently asked questions
Does the interest rate matter much for a short-term savings goal?
Not much — over a timeframe of a year or two, a typical savings-account interest rate contributes only a small fraction of the total balance compared to your own contributions. Interest matters far more over decade-long horizons, like retirement savings.
What if my contribution is too small to ever reach the goal?
This calculator simulates up to 100 years of monthly contributions and returns an error if the goal still isn't reached — a sign the monthly contribution needs to be larger, or the goal needs to be smaller, for a realistic timeline.
Why isn't there a simple formula for this like compound interest?
Compound interest alone (a lump sum growing on its own) has a clean closed-form formula. Adding a starting balance plus recurring monthly contributions plus compounding all together doesn't reduce the same way, so this simulates the balance growing month by month instead of solving it algebraically.
What if I want to know the required monthly contribution instead of the time?
This tool solves for time given a fixed contribution — for the reverse (a fixed timeline, solving for the contribution needed), try a few contribution amounts here and see which one reaches your goal within your target number of months.
Is my numbers uploaded anywhere?
No — Sparzielrechner runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.