The family loan calculator between us.
Lending to your kids, borrowing from your brother, helping a mate with a car? Put in the numbers and see how long it takes to repay, what the interest comes to, and how much you both keep compared with a bank.
- Total interest
- $1,501.96
- Total repaid
- $21,501.96
The same repayments on a bank loan at 11% would cost $5,032.68 in interest and take 7 months longer. Keeping it in the family saves $3,530.72.
| Year | Interest | Repaid | Balance |
|---|---|---|---|
| 2026 | $70.10 | $1,000.00 | $19,070.10 |
| 2027 | $684.88 | $6,000.00 | $13,754.98 |
| 2028 | $469.85 | $6,000.00 | $8,224.82 |
| 2029 | $243.03 | $6,000.00 | $2,467.86 |
| 2030 | $34.10 | $2,501.96 | $0.00 |
Now keep it honest,
between us.
Start a shared ledger for this loan. You both see the same balance, every repayment is recorded, and the interest runs on exactly these numbers.
Questions people ask
Can you charge interest on a loan to a friend or family member?
In most places, yes — two people can agree on any reasonable rate for a private loan, including 0%. Interest the lender receives is usually taxable income, and some tax offices have rules for larger family loans, so check how it works where you live before you lend a big amount.
What is a fair interest rate for a family loan?
A common rule of thumb is to land somewhere between what the lender earns on savings and what the borrower would pay a bank. If savings pay 4% and a personal loan costs 11%, anything in between leaves you both better off. Plenty of families simply choose 0%.
How does this calculator work out the interest?
Interest accrues every day at the annual rate divided by 365, and is added to the balance on the 1st of each month. Repayments come off on the same day each month as the loan started, and the final repayment is worked out to the day. It is the same engine that runs every betweenus ledger.
Is betweenus a bank or a lender?
No. betweenus is a record-keeping and calculation tool. It does not lend money, assess credit, or give financial advice — it keeps a shared ledger so both of you see the same numbers.