Calculate installment amounts, total interest, and a full payment schedule for any payment plan — with or without interest
Payment Plan Calculator — Model any installment arrangement in seconds:
Businesses on Xero and QuickBooks can automate payment plans end-to-end with Paidnice Payment Plans.
Each row shows how much of the payment goes to principal vs interest, and the remaining balance.
| # | Due Date | Payment | Principal | Interest | Balance |
|---|
What this means: The calculator uses the standard amortization formula. With interest, each payment covers a mix of principal and interest — early payments are mostly interest, later payments are mostly principal. For 0% plans, each payment is equal principal.
For business payment plans, remember to factor in opportunity cost (working capital tied up) and default risk when deciding whether to offer interest-free terms.
Offering payment plans to your customers?
Paidnice automates the entire payment plan workflow inside Xero and QuickBooks — proposal, acceptance, scheduled invoices, automated reminders, and default handling. No spreadsheets, no manual follow-up.
See how Paidnice Payment Plans works →This calculator provides estimates using the standard amortization formula. Actual fees, taxes, and late-payment charges are not included.
A payment plan (also called an installment plan, installment agreement, or payment schedule) is a structured arrangement where a total amount owed is broken into smaller, scheduled payments over a defined period. Instead of paying $10,000 upfront, a customer or borrower might pay $850 per month for twelve months — or $200 per fortnight for a year, depending on the terms.
Payment plans appear in almost every part of personal and business finance:
The math is identical across every context. What changes is the principal, the interest rate, the term length, and the payment frequency.
Payment = P × [ r(1+r)n ÷ ((1+r)n − 1) ]
For 0% interest plans: Payment = P ÷ n
Where: P = the principal (the amount financed, after any down payment)
And: r = the periodic interest rate (annual rate ÷ payments per year)
And: n = the total number of payments across the full term
A wholesale supplier agrees to let a customer pay down a $10,000 invoice over 12 months at 0% interest, with a 10% down payment:
The same $10,000 invoice with an 8% annual interest rate over 24 months, no down payment:
Because the same formula governs every type of plan, it's easier to build intuition by seeing real scenarios side by side:
| Scenario | Amount | Rate | Term | Payment | Total Interest |
|---|---|---|---|---|---|
| B2B invoice plan (0%) | $5,000 | 0% | 6 mo | $833.33 | $0 |
| B2B plan with finance fee | $10,000 | 8% | 24 mo | $452.27 | $854.40 |
| IRS short-term installment | $8,000 | 8% | 12 mo | $695.87 | $350.41 |
| Personal loan (good credit) | $15,000 | 12% | 36 mo | $498.22 | $2,935.92 |
| Auto loan (new car) | $25,000 | 6% | 60 mo | $483.32 | $3,999.20 |
| Credit card payoff | $5,000 | 22% | 24 mo | $259.52 | $1,228.48 |
The same principal amount can produce dramatically different outcomes depending on rate and term — which is why the calculator at the top of this page is more useful than rules of thumb.
The interest rate is the single biggest lever on total plan cost. A 2% difference in APR on a $25,000 loan over five years can easily mean $1,500 in extra interest.
Twelve percent is a useful mid-range benchmark. On a $10,000 loan:
The pattern is consistent: lower monthly payments come from longer terms, but total interest climbs non-linearly.
26.99% is a common credit card APR. On a $5,000 balance:
At the 60-month mark, you'd pay nearly twice the original balance — which is why credit card debt is often worth consolidating into a lower-rate installment loan.
34.9% APR sits near the top of the legal consumer credit range in most US states and the UK. For context:
A 34.9% APR is expensive but not predatory in the consumer context. In business-to-business payment plans, though, it would be well outside the norm — typical B2B plans run between 0% and 8%. If you're charging more than that on an invoice plan, you're likely better served by treating the debt as a collections matter and using a Late Payment Interest Calculator to work out statutory interest instead.
| Plan Type | Typical Interest Range | Notes |
|---|---|---|
| B2B customer payment plan | 0–8% | Often 0% to preserve relationships |
| Early payment discount (implied cost) | 18–37% effective APR | See the Early Payment Discount Calculator |
| IRS installment agreement | 7–10% | Federal short-term rate + 3%, adjusted quarterly |
| Personal loan (good credit) | 6–12% | Unsecured; rate depends on credit score and lender |
| Credit card | 18–30% | Higher for cash advances and penalty rates |
| Auto loan (new, good credit) | 4–8% | Secured by the vehicle |
Every payment plan involves a trade-off between how much is paid per period and how much is paid overall. Longer terms feel more comfortable per payment but cost more in total. Shorter terms are harder on monthly cash flow but cheaper end to end.
A longer term spreads the principal and interest across more payments:
A shorter term concentrates payments into a smaller window:
A rough rule of thumb: for individuals, total debt service (all payment plans combined) should stay under about 35% of net monthly income. For businesses offering payment plans to customers, keeping a given customer's plan obligation under 5% of their observable monthly revenue is a reasonable guardrail against default.
For businesses on Xero or QuickBooks, offering customers a structured payment plan has become a common alternative to either full payment or a write-off. Done well, it preserves the customer relationship, protects the receivable, and accelerates cash compared to a prolonged collections process. Done poorly, it creates administrative sprawl and pushes default risk down the road.
10–30% upfront is typical for a first-time plan customer. It reduces your exposure, confirms the customer's intent to pay, and meaningfully improves collection rates on the remaining installments.
Tie the term to the customer's natural cash cycle. Monthly plans of 3–12 months are most common in B2B. Anything beyond 12 months starts to look more like a loan than a payment plan, and opens questions about licensing and usury.
0% is the norm for short B2B plans. If you're holding the receivable longer than 6 months, consider charging interest to offset your cost of capital — but keep it modest (4–8%) to preserve the relationship. The Net 30 Calculator is useful for comparing against your standard terms.
A signed agreement, not just an email thread. Include the schedule, default provisions, acceleration clauses (the full balance becomes due on missed payment), and late-payment fees. Most disputes stem from unclear terms, not genuine disagreement.
Manual tracking of payment plans is where they go to die. Scheduled invoices, automated reminders ahead of each due date, and a clear escalation path for missed payments keep the plan running without consuming AR-team time.
Decide in advance what happens on a missed payment. Common approaches: a 5-day grace period, then a late fee and a formal notice. After two missed payments, acceleration of the full balance. Pair this with an AR aging review to catch slipping plans early.
Excel and Google Sheets both include a built-in PMT function that handles the payment plan formula directly:
=PMT(rate, nper, pv)
Where:
rate = periodic interest rate (annual rate ÷ payments per year)nper = total number of paymentspv = present value, entered as a negative number so the payment displays positiveExample: $10,000 at 8% annual interest, monthly payments over 24 months:
Returns $452.27, matching the calculator above. For a 0% interest plan, skip PMT entirely and use:
For a full amortization schedule, add columns for period number, interest portion (previous balance multiplied by the periodic rate), principal portion (payment minus interest), and running balance. Or skip the spreadsheet work and use the calculator at the top of this page — it generates the full schedule and exports to CSV.
Manual payment plans are a second job. Paidnice Payment Plans handles the whole workflow inside Xero and QuickBooks — proposal, customer acceptance, scheduled invoices, automated reminders, late fees, and default escalation. Your team sets the terms once; Paidnice runs the plan. See the Paidnice ROI Calculator to model what this is worth to your business.
See Paidnice Payment Plans →To calculate monthly loan installments, use the standard amortization formula:
Payment = P × [r(1+r)n ÷ ((1+r)n − 1)]
Where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments.
For a $10,000 loan at 8% annual interest over 24 months: r = 0.08 / 12 = 0.00667, n = 24, so the monthly payment comes out to $452.27. If the loan has no interest, the formula simplifies to P ÷ n — $10,000 ÷ 24 = $416.67 per month.
The calculator at the top of this page does the math automatically and also supports weekly, fortnightly, and quarterly frequencies.
Installment payments are calculated using the amortization formula: Payment = P × [r(1+r)n ÷ ((1+r)n − 1)], where P is the principal, r is the periodic interest rate, and n is the number of payments.
The steps:
=PMT(rate, nper, -pv) in ExcelThe output is the amount due each period. Multiply by the number of payments and add any down payment to get total cost.
Twelve percent usually refers to an annual interest rate (APR) of 12%. On a monthly-payment loan, the periodic rate becomes 1% per month (12% ÷ 12).
For a $10,000 loan at 12% APR:
Twelve percent APR sits at the upper end of good-credit personal loans and the lower end of credit card rates. It's a useful benchmark when comparing offers.
26.99% APR is a typical credit card rate. Applied to a $5,000 balance:
At five years, the total interest almost equals the original balance. Paying more than the minimum dramatically shortens the payoff and cuts the interest cost — on most credit card products, even modest extra principal payments help.
34.9% APR is expensive but not necessarily predatory in the consumer lending context. It sits near the top of the legal consumer credit range in the UK and most US states, and is commonly seen on sub-prime credit cards and secondary-market personal loans.
For context:
If you're being offered 34.9% APR, it's usually a sign your credit profile is being treated as higher risk. Before accepting, check whether a secured loan, a co-signer, or a balance-transfer card could lower the rate. For business payment plans, 34.9% would be far outside the norm — B2B plans typically run 0–8%.
It depends on the interest rate and term. Some common combinations for a $10,000 loan:
Longer terms lower the monthly payment but increase total interest. A $10,000 loan at 10% paid over 60 months costs $12,748 in total — an extra $2,748 compared to the $10,000 principal. The calculator at the top of this page shows the full amortization schedule for any combination.
A payment plan calculator is a free tool that works out the periodic payment amount, total interest, and full amortization schedule for an installment arrangement. You enter the total amount, any down payment, the interest rate (or leave it at 0% for interest-free plans), the number of installments, and the payment frequency. The calculator returns the payment per period, total paid over the life of the plan, and a row-by-row breakdown showing how each payment splits between principal and interest.
Payment plan calculators are used by consumers comparing loan offers, businesses offering installment terms to their customers, taxpayers setting up installment agreements with the IRS or ATO, and anyone modeling a credit card or debt payoff schedule.
A business payment plan on Xero or QuickBooks typically works like this:
Manually running this process consumes significant AR-team time. Paidnice Payment Plans automates the whole workflow — proposal, acceptance, scheduled invoicing, reminders, fees, and escalation — directly inside Xero and QuickBooks.
0% interest plans are standard in short-duration B2B payment arrangements — typically under 6 months. They preserve the customer relationship, signal goodwill, and convert what might otherwise become a write-off into full-value revenue collected over time.
The hidden cost of a 0% plan is your opportunity cost on the working capital tied up. If your cost of capital is 8% per year and you extend a $10,000 plan over 6 months, you're effectively giving up about $200 in opportunity value. Whether that's acceptable depends on the alternative — losing the customer entirely is almost always worse.
For plans longer than 6 months, consider charging a modest finance fee (4–8%) to partially offset your cost of capital while still keeping the plan competitive against consumer credit options.
The interest rate is the cost of borrowing the principal, expressed as a percentage of the outstanding balance per year. The APR (Annual Percentage Rate) includes the interest rate plus certain fees — origination fees, application fees, and any required insurance — expressed as an annualized percentage.
For a loan with no fees, the APR equals the interest rate. For a loan with $500 in origination fees on a $10,000 principal, the APR will be noticeably higher than the stated interest rate because the fee is amortized across the loan's life.
When comparing offers, APR is the more useful number because it captures the full cost of credit. The calculator on this page uses interest rate directly, so if you want to model APR, use the APR value as the input.
Payment plans are one piece of a healthy accounts receivable process. These free tools pair well with this calculator:
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