Example 1 — Typical mortgage
- Amount 400,000, 25 years
- Base 5.75% + margin 2.00%
Rate 7.75%
Margin share ≈ 26%
5.75 + 2.00 = 7.75. Margin is about a quarter of the combined rate.
Loan margin
Compute the total nominal rate (reference/base + lender margin), payment, and all-in cost. Compare two margins — without live market-rate feeds.
Total nominal rate = reference/base rate + lender margin. You enter the index from your offer (e.g. SOFR, EURIBOR, WIBOR) — we do not fetch live quotes. Educational margin and cost comparison, not a market tracker.
Result
Enter data and click Calculate.
How results are calculated
Total nominal rate = base + margin (or a custom override). Payment = annuity from amount, rate, and term.
Interest = total of payments − principal. All-in = total of payments + origination + monthly fee × months.
Margin / base share = component ÷ composed rate × 100%. With Scenario B we show payment and all-in differences.
How to use the calculator
- Enter the loan amount, reference/base rate from your offer, lender margin, and term in years.
- Optionally add fees or compare Scenario B with another margin.
- Read total nominal rate, payment, interest, all-in, and margin vs base share.
- With B active, see how much the margin gap costs in payment and lifetime all-in.
Usage examples
Example 2 — Margin 1.8% vs 2.3%
- 400,000, base 5.75%, 25 years
- A: margin 1.8% + fees
- B: margin 2.3%
Δ payment ≈ +132/mo.
Δ all-in ≈ +39,500
Half a percentage point of margin adds up over a long term.
Example 3 — Lower margin vs higher fee
- 300,000, base 5%, 30 years
- A: margin 2.5%
- B: margin 1.9% + origination 3,500
B cheaper all-in
despite the fee
A lower margin often beats a higher upfront fee over a long term — compare all-in.
How to interpret the result
- The result shows how base rate + lender margin translates into the nominal rate, instalment, and total cost in a simplified model.
- It is a useful way to see how even a small margin change can affect the monthly payment and long-term cost.
- It is not a statutory APR tool or a live market-rate tracker – it is meant to compare how sensitive an offer is to margin changes.
When to choose another tool
- Educational “margin × principal” sketch → Cost of loan margin sketch
- Fuller total-offer cost view → Total cost of loan
- Annual cost percentage style estimate → APR estimate
FAQ
What is loan margin?
The lender’s spread over the reference/base rate. Total nominal rate = base + margin — the rate used for the payment in this model.
Margin vs reference/base rate?
The reference/base rate (e.g. SOFR, EURIBOR, WIBOR) comes from your offer — you type it in. Margin is the lender’s fixed/negotiable spread. With a variable rate the base can move; margin usually stays in the contract.
Fixed vs variable context?
This calculator assumes a constant total rate over the term (educational). With a variable rate the real payment moves with the index — here you compare the effect of margin at a given base.
Why do small pp differences matter?
Interest accrues on the balance for many years. A 0.5 pp margin gap on a large principal can mean tens of thousands in all-in cost — that is why Scenario A vs B exists.
What is margin share of the combined rate?
Margin ÷ (reference rate + margin) × 100%. It shows how much of the combined rate is the lender’s spread.
Is the reference rate always WIBOR?
No — Poland often uses WIBOR/WIRON; elsewhere it may be SOFR, EURIBOR, etc. The field is a general base/reference rate.
Which related tools help next?
Simplified APR, loan instalment, and loan balance — to go from rate to cost, payment, and remaining principal.
When should you not rely on this alone?
When comparing full offer cost — you need fees, insurance, and APR/APRC, not margin by itself.