Four calculators for costs, budget and alternatives
Four calculators cover loan costs, repayment headroom, refinancing and overdraft comparison, all running locally in your browser without transmitting your inputs.
On this page
All Finanzierung-Guenstiger calculators run in your browser. Inputs are not transmitted to Thinkstars. Results are calculation models, not loan offers.
Which calculator fits?
Start with your budget, then calculate loan costs. For existing debts you compare the full remaining costs; for short-term shortfalls, the overdraft comparison helps.
- Maximum repayment: free headroom
- Loan costs: repayment and total amount
- Refinancing: old versus new
- Loan vs. overdraft: cost model
Each model is set out on its own page
Three of the four calculators use the same annuity formula: from the effective annual rate p, a monthly rate i = (1 + p/100)^(1/12) − 1 is derived, and from that the constant repayment K · i / (1 − (1 + i)^(−n)). The budget calculator uses simple subtraction. Each calculator page spells out its model in full, including the assumptions and what is not included. That is deliberate: a figure whose origin you cannot check is worthless as a basis for a decision.
What none of the calculators can do
None of them knows your personal offer. Advertised interest rates depend on your credit rating, and the repayment and total amount only become reliable with a specific offer. So wherever possible, enter figures from real offers, not from advertising. The models also do not reflect premium adjustments, downgrades or voluntary add-on products. Voluntary payment protection insurance, for example, lies outside the effective rate under § 16 Abs. 4 Nr. 2 PAngV — it increases your payments without changing the percentage you enter into the calculator.
In this section
Loan vs. overdraft
Compare the interest cost of a permanently used overdraft with an instalment loan and see the scale of the difference.
Read moreLoan costs
Model the monthly repayment, interest cost and total amount for a loan amount, effective rate and term – directly in your browser, without data transfer.
Read moreMaximum repayment
Combine income, spending, current repayments and a safety reserve into a monthly amount that is free on paper – locally in your browser.
Read moreRefinancing
Set the remaining cost of your current financing against the total cost of a new loan and see the actual difference.
Read moreFrequently asked questions
How accurate are loan calculators?
The maths is exact; the inputs rarely are. Our calculators use the standard annuity formula and disclose it — if you enter real figures from an offer, the result is correct. If you calculate with an advertised rate, you are working with a figure you may never get.
Is a loan enquiry made when I calculate here?
No. The calculators run entirely in your browser. Nothing is sent to a bank, nothing to the SCHUFA credit bureau and nothing to us. Only when you deliberately load our partner's comparison and enter data there does anything leave your device.
Why does my offer differ from the calculated result?
Because the interest rate depends on your credit rating, which the calculator does not know. On top of that there are items that may lie outside the effective rate — voluntary payment protection insurance, for example, does not appear there but increases what you pay. So always compare the total amount, not just the percentage.