Mortgage calculator
A Spitzer schedule is the annuity method: the payment stays the same, and the share that pays interest falls as the balance falls. Equal principal keeps the principal portion fixed, so the payment itself falls over time.
The page shows every month, not a yearly summary. It ignores fees, insurance, taxes, and linked or variable tracks. A lender’s quote is the number that matters for a real mortgage.
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Use a comma or a dot for the decimal, as in 12.5 or 12,5. Type thousands as 1000 or 1 000. A single comma or dot is the decimal mark, so 1,000 means 1.
Results
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How to use this calculator
- Enter the amount, the annual interest rate, and the term in whole years.
- Choose Spitzer (fixed payment) or equal principal.
- Read the first and last payments, then scroll the full schedule.
Formula
Payments are monthly. For Spitzer, i is the monthly rate and n is the number of months.
payment = P × i × (1 + i)^n / ((1 + i)^n − 1)
Equal principal pays P / n of the balance each month, plus interest on what is left. A zero rate makes both methods an even split. Money is rounded to the nearest hundredth, and the last row clears the balance.
Worked example
100,000 at 6 percent for one year
There are 12 monthly payments. The Spitzer payment is about 8,606.64.
Equal principal pays 8,333.33 of principal every month. The first payment is higher because the whole balance is still earning interest.
Spitzer: about 8,606.64 each month. Equal principal starts higher and then declines.
Questions
Is Spitzer only an Israeli method?
The name is used for Israeli mortgages. The arithmetic is the standard fixed payment, also called an annuity or French amortization.
Why is the first equal-principal payment higher?
Interest is charged on the full balance in month one. The principal slice does not shrink, so the total payment is largest at the start.
Does this include insurance or a linked index?
No. Those change the amount you actually pay. This is the interest-and-principal schedule only.
Sources
Last reviewed November 12, 2026