1. The Reality Check

Sales tax and GST (Goods and Services Tax) show up on nearly every purchase, yet most people can't quickly calculate what portion of a price is tax versus base cost — a skill that matters for budgeting, business invoicing, and expense reports.

2. Plain English Definition

GST/sales tax is a percentage added to (or already included in) the price of goods and services. Calculating it means finding either the tax amount, the pre-tax price, or the total, depending on what you already know.

3. Inclusive vs. Exclusive Tax

"Exclusive" pricing means tax is added on top of the listed price at checkout (common in the US). "Inclusive" pricing means the tax is already baked into the sticker price (common in the EU, India, and Australia). Confusing the two leads to consistently wrong calculations.

4. Key Terms

• Net Amount: The price before tax.
• Gross Amount: The price after tax is added.
• Tax Rate: The percentage applied, which varies by product category and jurisdiction.

5. Next Steps

Use the calculator above to instantly split any price into its net amount and tax component, or add tax to a base price.