How to Use a Financial Calculator: N, I/Y, PV, PMT and FV

Learn the five time value of money keys, the sign convention that trips everyone up, and how to solve loan, savings and payoff problems.

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Free tool: Financial Calculator (TVM)

Financial calculators like the BA II Plus and HP 12C solve almost any loan or savings problem with five keys. Once you know what each one means and how the signs work, you can find a payment, a balance, an interest rate or the time to reach a goal in seconds. This guide explains the method with four common examples, using the free Financial Calculator (TVM).

The five keys

  • N: the number of periods (payments).
  • I/Y: the yearly interest rate.
  • PV: present value, the amount at the start.
  • PMT: the payment each period.
  • FV: future value, the amount at the end.

Enter any four and solve for the fifth. P/Y (payments per year) and C/Y (compounding per year) set the period length, usually 12 for monthly.

The sign convention

Money you receive is positive and money you pay out is negative. A loan you take out is a positive PV (you receive it) and negative payments. A savings plan has a negative PV and negative payments (you pay in), and a positive FV (you get it back). Most errors come from getting a sign wrong.

Example 1: a car loan payment

N = 60, I/Y = 6, PV = 25,000, FV = 0, solve for PMT: −$483.32 a month. You'd pay $28,999.20 in total, $3,999.20 of it interest.

Example 2: a savings goal

N = 240, I/Y = 7, PV = −10,000, PMT = −500, solve for FV: $300,850.72 after 20 years.

Example 3: a loan's interest rate

A $300,000 loan with 360 payments of $1,896.20: N = 360, PV = 300,000, PMT = −1,896.20, FV = 0, solve for I/Y: 6.5%.

Example 4: months to pay off a card

A $5,000 credit card balance at 22.9% with $200 monthly payments: I/Y = 22.9, PV = 5,000, PMT = −200, FV = 0, solve for N: about 34.3 months.

Payment timing

Most loans and many savings plans pay at the end of each period (END). Rent and leases are often paid at the start (BGN). Paying at the start earns or costs one extra period of interest on each payment.

Common uses

The same five keys handle mortgages and refinancing, retirement and college savings, bond-style cash flows and annuities. For dedicated tools with charts, see the Loan Calculator and Future Value Formula Explained.

How to use the Financial Calculator

  1. Open the Financial Calculator (TVM), or start from one of the presets: car loan payment, savings goal, loan interest rate or months to pay off a card.
  2. Choose what to solve for: N, I/Y, PV, PMT or FV.
  3. Enter the other four values, using negative numbers for money you pay out.
  4. Set payments and compounding per year and the payment timing.
  5. Read the results: the solved value, the rate per payment period, the total of all payments and the total interest, with a chart of the balance after each period and a balance-by-year table.

Frequently asked questions

What do N, I/Y, PV, PMT and FV mean?

Number of periods, yearly interest rate, present value, payment and future value. Enter four and the calculator solves the fifth.

Why is my payment negative?

Because it's money you pay out. The calculator follows the standard sign convention: money in is positive, money out is negative.

What is the difference between P/Y and C/Y?

P/Y is how many payments you make a year; C/Y is how many times interest compounds. They're usually both 12, but Canadian mortgages, for example, compound semi-annually with monthly payments.

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