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Pay now or in installments: which is better?

Compare a discount for paying now with splitting the price into installments. The calculator shows the hidden interest, what your money would earn in the period and which option is cheaper in today’s money.

Educational simulation. Not investment advice. Results are estimates based on the data you enter and do not replace advice from a qualified professional.

Reviewed on Oct 31, 2026

Example: a $1,200 item with 5% off if you pay now, or 12 “interest-free” installments.

Price and paying now
Price if you pay now—
Installments

How do you want to simulate?

Installment—
Total in installments—
What your money would earn

The savings rate is what your money earns where you keep it today; “another return” is an alternative you could use, such as a bond fund.

Your inputs stay only on this browser and are not sent anywhere. Untick to delete them.

—Best option
—

What if you pay in installments and keep the money invested?

The pay-now price stays invested and each installment comes out of it on its due date. If the line ends above zero, installments paid off; below zero, the money ran out.

Tap the chart to see the values.

What each option costs in today’s money

The installments brought to today’s value at the return your money would earn, compared with paying now.

Tap the chart to see the values.

With another discount or number of installments

Which option wins in each combination and by how much, at your savings rate. Your simulation is in the center; tap a cell to center on it.

paying now winsinstallments win· value = advantage in today’s money
Installment by installment

The pay-now price invested, paying each installment when due. Each row closes like this: Starting balance + Interest − Installment = Ending balance.

Before you buy: do you need it now?

The best way to pay does not turn an unnecessary purchase into a good one. Before choosing how to pay, answer honestly:

  • Would I buy it if I had to pay it all today? If not, the installments are making it easy to buy something that does not fit your budget.
  • Wait 24 to 72 hours. Impulse buys tend to lose their appeal after a day or two; if you still want it, the purchase probably makes sense.
  • Add this payment to the ones you already have. Small payments add up and tie up the coming months. A common guideline is to keep all debt payments below 30% of monthly income.
  • Do not use your emergency fund for purchases that can wait, and do not split payments if it pushes your card to its limit.
  • Compare prices at other stores: sometimes the “discount” is just a return to the normal price.

The summary lists your inputs, results, formulas, assumptions and sources. The full report also includes the charts and interpretations, in color. In the print dialog, choose Save as PDF.

Method, assumptions and sources

Formulas

Pay-now price = price × (1 − discount)
Real cost: rate i such that installment × [1 − (1 + i)^−n] ÷ i = pay-now price (×(1 + i) if the 1st installment is at purchase)
Net monthly return = [(1 + yearly rate)^(1/12) − 1] × (1 − tax rate)
Advantage of installments = pay-now price − present value of the installments

Assumptions and limits

  • The official cost is the one stated by the store or lender. This is not purchase advice.
  • Equal monthly installments; equivalent rates by compound interest; monthly return from the yearly rate entered, less a flat tax. Card fees, rewards and cash back are ignored.

Official sources and references

Frequently asked questions

Is it better to pay now or in installments?

It depends on two numbers: the hidden interest of the installments compared with the pay-now price, and what your money earns after tax. If the hidden interest is higher, paying now is cheaper; if it is lower and you really keep the money invested, installments come out ahead.

Do “interest-free” installments have interest?

When there is a discount for paying now, yes: the difference between the full price and the discounted price is the interest built into the installments.

How do I read the default example?

A $1,200 item costs $1,140 if you pay now, or 12 installments of $100. Giving up the 5% discount is like borrowing at about 0.80% a month; a 4.5% savings rate taxed at 20% earns much less, so paying now wins. The page shows the advantage in today’s money.

Where do I get the rates?

The savings rate is the yearly rate your account or certificate of deposit actually pays. “Another return” is an alternative you would use. For the tax, type the rate that applies to interest income for you, or 0% for a tax-free account.

What does “in today’s money” mean?

Each future installment is discounted at the return your money would earn until it is due. Adding these present values shows what the installments really cost today, so they can be compared with paying now.

What does the calculator leave out?

Card fees, late interest, foreign transaction fees, rewards points and cash back. If you would not really keep the money invested, or might carry a card balance, paying now is usually safer.

Should I use my emergency fund to pay now?

No. The emergency fund is for the unexpected. If paying now would empty it, splitting an interest-free purchase may be the prudent choice, even if it costs a little more in theory.

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Pay now or in installments: how to know which is cheaper

Stores often offer two prices: a discount if you pay the full amount today, or the full price split into “interest-free” installments. If there is a discount for paying now, the installments are not really free: the discount you give up is the interest. The question is whether that hidden interest is higher or lower than what your money would earn if you kept it.

The hidden interest rate

Find the monthly rate that makes the installments equal to the pay-now price. A 5% discount on a $1,200 item paid in 12 monthly installments of $100 hides a rate of about 0.80% a month, or 10% a year. If your savings earn less than that, after tax, paying now is cheaper.

Compare in today’s money

Installments are paid in the future, so adding them up is misleading. Bring each payment to today’s value using the return your money would earn, add them, and compare the total with the pay-now price. The calculator does this and also simulates keeping the pay-now amount invested and paying each installment from it.

When installments make sense

When there is no discount for paying now, when the discount is small compared with what your savings earn, or when paying now would drain your emergency fund. It only works if you pay the card bill in full and on time: credit card interest wipes out any advantage.