Simple Calculator Online: Free Basic Calculator

Need a quick answer? This free simple calculator handles everyday arithmetic, brackets and percentages, and keeps a history of your recent calculations. Tap the keys or type with your keyboard; the answer appears as you type.

How to use it

• Type or tap numbers and the operations \( + \), \( - \), \( \times \), \( \div \).
• Press = (or Enter) to finish a calculation. Keep typing an operation to continue from the result.
• ⌫ deletes the last character; AC clears everything.
• History (below the keys) lists your last 10 results. Tap one to reuse it.
• Brackets and percentages work anywhere in an expression.

Order of operations (PEMDAS / BODMAS)

The calculator uses the standard order: Parentheses, Exponents, Multiplication and Division (left to right), Addition and Subtraction (left to right).

Expression	Answer	Why
\( 2 + 3\times4 \)	14	multiply first
\( (2 + 3)\times4 \)	20	brackets first
\( 8 - 2\times3 + 1 \)	3	multiply, then left to right
\( 100\div5\div2 \)	10	divide left to right
\( 3\times(4 + 6)\div5 \)	6	brackets, then left to right
\( 12\div3\times2 \)	8	left to right, not \( 12\div6 \)

Two details trip people up most often.

Multiplication doesn’t come before division. They have equal priority and are done left to right, and the same goes for addition and subtraction. The “M before D” in PEMDAS is only the order of the letters. So \( 12\div3\times2 \) is \( 4\times2 = 8 \), not \( 12\div6 = 2 \).

Ambiguous expressions need brackets. Puzzles like \( 6\div2(1 + 2) \) circulate online because people read them differently. This calculator treats the implied multiplication like an ordinary ×, working left to right, so it gives 9. If you meant \( 6\div\big(2(1 + 2)\big) = 1 \), type the extra brackets. When in doubt, bracket the part you want done first: brackets always win.

A handy habit is to estimate before you press =. For \( 3\times(4 + 6)\div5 \), think “3 times 10 is 30, a fifth of that is 6.” If the calculator shows something very different, look for a missing bracket.

Percentages made simple

The % key divides by 100, so “15%” means 0.15.

• 15% of 80: 15% × 80 = 12
• Add 15% (tip or tax) to 80: 80 × 115% = 92
• Take 15% off 80 (a discount): 80 × 85% = 68
• What percent is 12 of 48? 12 ÷ 48 × 100 = 25%
• Percentage change from 48 to 60: (60 − 48) ÷ 48 × 100 = 25% increase

Adding or taking off a percentage: 80 + 15%

Typing 80 + 15% gives 92, and 80 − 15% gives 68. When a percentage is added to or subtracted from an amount, the calculator treats it as a percentage of that amount, the way phone and shop calculators do. You can chain them: 200 − 10% − 10% = 162, because each discount applies to the new total. Everywhere else, % simply means “divide by 100”, so 15% × 80 = 12 and 80 × 115% = 92.

A jacket costs 60 after a 20% discount. What was the original price? The sale price is 80% of the original, so divide by 0.8: 60 ÷ 0.8 = 75. (With the % key, 60 ÷ 80% also gives 75.) Adding 20% to 60 gives 72, which is wrong, because the 20% was taken from the original price, not from 60.

The same idea removes sales tax. If a receipt total of 54 includes 8% tax, the pre-tax price is 54 ÷ 1.08 = 50.

Percent changes don’t simply add

• Up 25%, then down 25% does not bring you back. Starting from 100: 100 × 125% × 75% = 93.75.
• Two discounts of 20% and 10% are not 30% off. Starting from 100: 100 × 80% × 90% = 72, which is 28% off.
• Direction matters for percentage change. From 48 to 60 is a 25% increase, but from 60 back to 48 is a 20% decrease: (60 − 48) ÷ 60 × 100 = 20. The base is always the starting value.

Also watch the difference between percent and percentage points. An interest rate rising from 4% to 5% goes up 1 percentage point, but that’s a 25% increase in the rate.

Everyday examples

1. Splitting rent: \( 1250\div4 = 312.50 \) each.
2. Tip at 18% on a bill of 45.60: \( 45.60\times18\% \approx 8.21 \).
3. Test score: 18 out of 24 is \( 18\div24\times100 = 75\% \).
4. Best value at the store: 12 eggs for 4.20 cost \( 4.20\div12 = 0.35 \) each; 18 eggs for 5.85 cost \( 5.85\div18 = 0.325 \) each, so the larger pack is cheaper per egg.
5. Fuel economy: 350 miles on 14 gallons is \( 350\div14 = 25 \) miles per gallon.
6. Average of test scores 82, 90 and 77: (82 + 90 + 77) ÷ 3 = 83. The brackets matter; without them you’d divide only the 77 by 3.
7. Weighted grade: if two tests count 30% each and a final counts 40%, scores of 82, 90 and 77 give 82 × 30% + 90 × 30% + 77 × 40% = 82.4.
8. Pay for part of a shift: 2.5 hours at 18.50 per hour is \( 2.5\times18.50 = 46.25 \).
9. Scaling a recipe by 1.5: \( \frac34 \) cup of flour becomes \( 0.75\times1.5 = 1.125 \) cups, a little over 1 cup.
10. Savings growth: 1000 at 5% per year for 3 years is 1000 × 105% × 105% × 105% ≈ 1157.63. Each year’s growth is applied to the new total, which is compound interest.

For longer stretches of compound growth, the exponential growth calculator does the repeated multiplication for you, and the geometric series formula adds up regular deposits.

Why does 0.1 + 0.2 sometimes look odd?

Computers store decimals in binary, so \( 0.1 + 0.2 \) is really \( 0.30000000000000004 \) inside the machine. This calculator rounds results to 12 significant digits, so it shows the answer you expect: 0.3.

Dividing by zero

\( 7\div0 \) has no answer, so the calculator shows an error message instead of a misleading number.

Need more functions?

For square roots, powers, trig and logarithms, use the scientific calculator. To see how a formula behaves over a whole range of inputs rather than one number, plot it with the graphing calculator. If you’re averaging a quantity that changes continuously, like temperature over a day, the calculus version is the average value of a function. For algebra and calculus with full working, try the step-by-step solver or browse our calculus concepts guide.

Practice problems

1. \( 7 + 8\times2 \)
2. \( 20\% \) of 350

3. \( (15 - 3)\div4 \)

4. \( 12\div3\times2 \)

5. A price is 40 after a 20% discount. What was the original price?
6. 200 is reduced by 10% twice. What is the result?

Answers: (1) \( 23 \); (2) \( 70 \); (3) \( 3 \); (4) \( 8 \); (5) \( 50 \), since \( 40\div0.8 = 50 \); (6) \( 162 \), since \( 200\times90\%\times90\% = 162 \), not 160.

FAQ

Is this calculator free?

Yes. It runs in your browser with no sign-up, and nothing you type is sent to a server.

Does it work on phones?

Yes. The keys are sized for touch, and on phones the on-screen keypad is used instead of your phone’s keyboard.

How do I calculate a percentage of a number?

Multiply the number by the percent. For 20% of 350, type 20% × 350 or 350 × 0.2; both give 70.

How do I find the original price before a discount?

Divide the sale price by the percentage you actually paid. After a 25% discount you pay 75%, so the original price is the sale price divided by 0.75. You can type the decimal or the percentage, like 60 ÷ 75%; both give 80.

How do I add 15% to a number?

Type 80 + 15% and the calculator gives 92: it adds 15% of 80. 80 − 15% takes 15% off and gives 68. You can also write 80 × 115% if you prefer to think of the new amount as 115% of the old one.

Why is 2 + 3 × 4 not 20?

Multiplication is done before addition, so it’s \( 2 + 12 = 14 \). Use brackets, \( (2 + 3)\times4 \), to get 20.

Further reading

• Order of operations (Wikipedia) — PEMDAS, BODMAS and the history of the conventions, including ambiguous cases.
• Percentage (Wikipedia) — percentage change, percentage points and why successive changes don’t add.
• Floating-point arithmetic (Wikipedia) — why computers show results like 0.30000000000000004.