Finding Total Price with Tax

Learn how to calculate the total cost of an item when sales tax is added.

Intermediate20 minLesson
Printable worksheet

Definition

When you buy something, you often pay more than the listed price because of sales tax. To find the total price, you add the tax to the original price.
The Formula:
Total Price=Original Price+Tax Amount\text{Total Price} = \text{Original Price} + \text{Tax Amount}
Where:
Tax Amount=Original Price×Tax Rate\text{Tax Amount} = \text{Original Price} \times \text{Tax Rate}
The Shortcut (One-Step Method):
Total Price=Original Price×(1+Tax Rate)\text{Total Price} = \text{Original Price} \times (1 + \text{Tax Rate})
For example, with an 8% tax rate:
Total Price=Original Price×1.08\text{Total Price} = \text{Original Price} \times 1.08

Try it now

A shirt costs 25 dollars. With 8% sales tax, which calculation gives the total price?

Worked Examples

A backpack costs 40 dollars. The sales tax is 8%. What is the total price?
1

Identify the values

Original price = 40 dollars, Tax rate = 8% = 0.08 → Values identified
2

Calculate the tax amount

40×0.08=3.2040 \times 0.08 = 3.20 → Tax = 3.20 dollars
3

Add tax to original price

40+3.20=43.2040 + 3.20 = 43.20 → Total = 43.20 dollars

Common Mistakes

Calculating tax but forgetting to add it to the original price

Why it's wrong: Finding the tax amount is only half the problem. You need to add it to get the total you actually pay.

Correct: Always complete both steps: calculate tax, then add it to the original price. Or use the shortcut: multiply by (1+tax rate)(1 + \text{tax rate}).

Using the tax rate as the multiplier directly (e.g., multiplying by 0.08 instead of 1.08)

Why it's wrong: Multiplying by 0.08 gives you only the tax amount, not the total price. You need to include the original 100%.

Correct: For the one-step method, add 1 to the tax rate. With 8% tax, multiply by 1.08, not 0.08.

Not rounding to two decimal places for money

Why it's wrong: Money calculations should be rounded to the nearest cent (two decimal places).

Correct: Always round your final answer to two decimal places when working with currency.

Moving the decimal point incorrectly when converting percentages

Why it's wrong: 8% equals 0.08, not 0.8 or 8.0. Each percent equals one hundredth.

Correct: To convert a percentage to a decimal, divide by 100 (move decimal point two places left). 8% = 8 ÷ 100 = 0.08

Interactive Visual

Bar Chart

Backpack for 40 with 8% sales tax

Price(40)
Tax(3.2)
Total(43.2)

Interactive Sandbox

Expression Calculator

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Practice Problems

18 problems
Problem 1 of 18
Easy
A shirt costs 25 dollars. With 8% sales tax, which calculation gives the total price?

Why It Matters

Understanding how to calculate total price with tax is essential for everyday life:
  • Shopping: Know exactly how much you'll pay before reaching the checkout
  • Budgeting: Plan your spending accurately by accounting for tax
  • Comparing prices: Determine the true cost when shopping at stores with different tax rates
  • Financial planning: Make informed decisions about purchases big and small
Without this skill, you might not bring enough money to the store or overspend your budget!

Real World Applications

Shopping Trip Budget

When shopping, knowing the total with tax helps you stay within your budget.

Example:

You have 50 dollars to spend. A shirt costs 45 dollars. With 8% tax, the total is 45×1.08=48.6045 \times 1.08 = 48.60 dollars. You can afford it!

1Try It Yourself

You want to buy a pair of headphones priced at 35 dollars. The sales tax in your area is 6%.

What is the total price you will pay?

Step 1: Write the mathematical expression

Calculate: 35 dollars × 1.06

Restaurant Bills

Restaurant prices often don't include tax, so you need to calculate the total before tipping.

Example:

Your meal costs 28 dollars before tax. With 7% tax: 28×1.07=29.9628 \times 1.07 = 29.96 dollars. Now you can calculate your tip on top of that!

2Try It Yourself

Your family's dinner bill is 75 dollars before tax. The restaurant tax rate is 8%.

What is the subtotal including tax (before tip)?

Step 1: Write the mathematical expression

Calculate: 75 dollars × 1.08

Online Shopping

Online stores may show prices without tax until checkout. Knowing how to calculate helps you avoid surprises.

Example:

A laptop is listed at 899 dollars. With 5% tax: 899×1.05=943.95899 \times 1.05 = 943.95 dollars total.

3Try It Yourself

You're buying a phone case online for 19.99 dollars. Your state charges 10% sales tax.

What will the checkout total be?

Step 1: Write the mathematical expression

Calculate: 19.99 × 1.10

Key Takeaways

  • 1Total price equals the original price plus the tax amount
  • 2Tax amount is calculated by multiplying the original price by the tax rate (as a decimal)
  • 3The shortcut: multiply the original price by (1+tax rate)(1 + \text{tax rate})
  • 4For 8% tax, multiply by 1.08. For 6% tax, multiply by 1.06. And so on.
  • 5Always round money to two decimal places (cents)

Frequently Asked Questions

The 1 represents 100% of the original price. When you multiply by 1.08, you're getting 100% of the price (the item itself) plus 8% more (the tax). So 1.08 means 108% of the original price.
The 1 represents 100% of the original price. When you multiply by 1.08, you're getting 100% of the price (the item itself) plus 8% more (the tax). So 1.08 means 108% of the original price.
Convert it the same way: 6.25% = 0.0625. Then use multiplier 1.0625. For a 40 dollar item: 40 × 1.0625 = 42.50 dollars.
No! Tax rates vary by location. Some places have no sales tax, while others charge 10% or more. Always check the local rate when calculating.

Glossary

Sales tax
A percentage of the purchase price collected by the government on retail sales
Original price
The listed or sticker price before tax is added
Total price
The final amount paid, including tax
Tax rate
The percentage charged as tax (e.g., 8% or 0.08)
Multiplier
The number you multiply by to find the total in one step (1 + tax rate)

Formula Card

Two-Step Method

Total=Price+(Price×Rate)\text{Total} = \text{Price} + (\text{Price} \times \text{Rate})

Calculate tax separately, then add

One-Step Shortcut

Total=Price×(1+Rate)\text{Total} = \text{Price} \times (1 + \text{Rate})

Direct calculation using multiplier

Today's challengeOne problem, three tries

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