What Is a Financial Calculator?

A financial calculator has keys for the problems finance keeps asking: loan payments, savings goals, the value of future cash and whether a project is worth doing. It works with five linked values. Enter any four and it finds the fifth.

N: the number of payment periods.
I/Y: the interest rate per year.
PV: the present value, the amount today.
PMT: the payment each period.
FV: the future value, the amount at the end.

Which calculator should I use?

This calculator: if you know these keys, or you're studying for a finance course.
Time Value of Money calculator: to fill in labelled boxes and see a chart and a written explanation.
Mortgage and Amortization calculators: for a full loan schedule you can download.

How It Calculates

The five keys always balance this equation:

PV + (1 + i k) \times PMT \times \frac{1 - {(1 + i)}^{- N}}{i} + FV \times {(1 + i)}^{- N} = 0

PV + (1 + i k) \times PMT \times \frac{1 - {(1 + i)}^{- N}}{i}

+ FV \times {(1 + i)}^{- N} = 0

Where i is the rate per payment period, and k is 1 for payments at the start of each period (BGN) or 0 for payments at the end (END).

The sign rule

Money you receive is positive, and money you pay out is negative. A loan you receive has a positive PV, and your payments come out negative. If a rate or period can't be solved, check that the signs aren't all the same.

How to Use the Financial Calculator

"What is the monthly payment on a $300,000 mortgage at 6% over 30 years?" This calculator answers that.

Let's enter the numbers for this example, key by key:

P/Y: Press 2ND, I/Y, 12, ENTER, then 2ND, CPT, which sets 12 payments a year and leaves that screen. Compounding (C/Y) follows it automatically.
N: Enter 360 and press N, which is 30 years of monthly payments.
I/Y: Enter 6 and press I/Y, which is the yearly interest rate.
PV: Enter 300000 and press PV, which is the amount you borrow. It's positive because you receive it.
FV: Enter 0 and press FV, which is what you still owe at the end.
CPT, PMT: Press CPT and then PMT, which solves for the payment: −1,798.65. It's negative because you pay it.

Over 30 years, those payments add up to $647,514.57.

Loan balance after a year

With the same loan entered, press 2ND, PV (AMORT). Enter 1, ENTER, ↓, 12, ENTER, then ↓. The balance after 12 payments is 296,315.96. Press ↓ twice more for the interest paid that year: −17,899.78.

NPV and IRR

Suppose you invest $1,000, then receive $300, $400 twice, and $500. Press these keys:

CF: Press CF, enter 1000, +|−, ENTER, which is the starting cash flow, negative because it's paid out.
C01 and F01: Press ↓, enter 300, ENTER, then ↓ twice to pass F01, which stays at 1 because it happens once.
C02 and F02: Enter 400, ENTER, ↓, 2, ENTER, because $400 comes twice.
C03: Press ↓, enter 500, ENTER.
NPV: Press NPV, enter 10, ENTER, ↓, CPT, which gives 245.34 at a 10% rate.
IRR: Press IRR, CPT, which gives 20.02%.

The other functions

Each one is printed above its key. Press 2ND first:

BGN (above PMT): switches payments between the end and the start of each period, using 2ND, ENTER (SET).
xP/Y (above N): multiplies a number of years by the payments per year.
ICONV (above 2): converts between nominal and effective rates.
Δ% (above 5): percent change, including over several periods.
PROFIT (above 3): cost, selling price and margin. Enter any two and compute the third.
BRKEVN (above 6): fixed cost, variable cost, price, profit and quantity.
FORMAT (above the decimal point): the number of decimal places shown, from 0 to 9. Calculations keep full precision.
STO and RCL: store and recall a number. Press STO or RCL, then a digit from 0 to 9.

Calculate and Clear

Arithmetic runs left to right as you press keys, so 2 + 3 × 4 = gives 20. Use parentheses when you want 14. The panel of stored values slides out when you press a key, and the arrow on the calculator's side opens or closes it. Values stay until you clear them or leave the page.

→: deletes the last digit.
CE/C: clears what you're typing or an error, but keeps stored values. With nothing typed, it also leaves a worksheet and clears the screen to zero.
2ND, FV (CLR TVM): clears the five time value keys. Do this before a new problem.
2ND, CE/C (CLR WORK): clears the worksheet you're in, such as the cash flows.
RESET, then ENTER: resets everything.

Using your keyboard

Click the calculator, then type digits and + - * / ^ ( ) . %. The ↑ and ↓ arrows move between rows, Backspace deletes, and Esc clears. Enter stores a value in a worksheet and finishes a sum otherwise.

For learning and general use. It's not financial advice, and for exams or important decisions you should check results with an approved calculator or a professional. Lenders may round payments differently.