Breakdown
Contributions vs Interest Earned (Savings Goal Breakdown)
Your projected end balance can be split into what you started with, what you added, and any modeled growth. This guide explains each part and shows how to see the breakdown in the calculator.
Published: December 22, 2025 · Updated: December 22, 2025 · By FinToolSuite Editorial
Open the calculator
See how your balance breaks down by starting amount, contributions, and any modeled growth.
Open the Savings Goal Timeline CalculatorQuick answer
Starting balance = what’s already there. Contributions = what you add. Growth = modeled extra from the rate assumption (if used).
Growth can snowball later in a constant rate model because it’s calculated on a larger balance.
Definitions: savings goal timeline glossary.
Disclaimer
Educational purposes only; not financial advice. Growth estimates depend on assumptions; real outcomes vary and results aren’t guaranteed. Fees, taxes, inflation, and rules vary by country and provider.
The three parts of your result
Starting balance
What you already have. It gets the full modeled duration to grow if a rate is included.
Contributions
What you add over time. For most short-to-medium goals, this is the biggest driver.
Growth / interest / earnings
Modeled extra from the rate assumption, if you set one. It’s optional and not guaranteed.
Why growth can accelerate
Growth is calculated on the current balance. As contributions build the balance, there’s more to grow. In a constant rate model, the growth portion can rise faster later even if the rate stays the same.
See the math: savings goal timeline formula.
Mini examples (illustrative)
Example 1: 0% baseline (all contributions)
- Goal: £2,400
- Start: £0
- Save: £200/month
- Rate: 0%
Takeaway: progress is purely contributions; the breakdown is straightforward.
Try it in the calculatorExample 2: Starting balance helps
- Goal: £5,000
- Start: £1,000
- Save: £150/month
- Rate: 0% baseline
Takeaway: a head start reduces what you need to add and can shorten the timeline.
Try it in the calculatorExample 3: Add an assumption (growth appears)
- Goal: £5,000
- Start: £1,000
- Save: £150/month
- Rate: low/base assumption you choose (illustrative)
Takeaway: a “growth” slice appears, but it depends on assumptions and isn’t guaranteed.
Try it in the calculatorHow to interpret the breakdown view
- Contribution total: how much you put in over the horizon.
- Growth total: modeled extra from your rate assumption (if any).
- Percent shares (if shown): see how much comes from you vs modeled growth.
For visuals, see savings goal timeline chart explained.
Common misreads
- Treating “growth” as guaranteed.
- Confusing contributions with earnings.
- Assuming a higher rate is “better” without considering uncertainty.
- Comparing scenarios where multiple inputs changed at once.
FAQ
What counts as “contributions”?
Your starting balance plus all deposits you add over time.
Is interest earned guaranteed?
No. It depends on the rate assumption and real outcomes can differ.
Why does growth look small early on?
Early balances are smaller, so the growth portion is smaller in a constant rate model.
Why does growth grow faster later?
As the balance rises, the same rate applies to a larger amount, so growth can accelerate.
Does weekly vs monthly change the breakdown?
Timing differences can shift totals slightly; the calculator will show the breakdown for your chosen frequency.
Should I run a 0% baseline?
Yes, it’s a clear view of pure contributions before adding any rate assumption.
Do fees, taxes, or inflation affect the breakdown?
They can reduce net growth. A lower rate assumption can be a simple illustrative buffer.
Where can I learn the math and definitions?
See the formula page and the glossary.
Run two scenarios
Test a 0% baseline and a low/base assumption to see how the breakdown shifts.
Open the Savings Goal Timeline Calculator