GST Calculator

Goods and Services Tax applies to the sale price of goods and services in many countries. Two operations cover the common cases: adding GST to a net (before-tax) price to find the gross total, and extracting GST from a gross (tax-inclusive) price to reveal the net amount and the tax portion. The GST rate defaults to 10% but changes to match any jurisdiction.

Common rates include 5% (Canada), 7% (Thailand), 10% (Australia), 15% (New Zealand), and 18% (India standard rate); a decimal rate such as 7.5 covers jurisdictions with non-integer percentages.

Adding GST: GST Amount = Net Price x (Rate / 100), and Gross Price = Net Price + GST Amount. Extracting GST: Net Price = Gross Price / (1 + Rate / 100), and GST Amount = Gross Price - Net Price.

Accepted amount formats include whole numbers (1000), decimals (49.95), fractions (3/4), mixed numbers (5 1/2), and scientific notation (1.5e3); dollar signs, commas, and percentage symbols are stripped automatically. Settings hold the number of decimal places (default 2) and a step-by-step view showing the formula substitution and intermediate values.

Adding GST at 15% (the New Zealand rate) to a $200 net price gives GST Amount = 200 x 0.15 = $30, and Gross Price = 200 + 30 = $230. Extracting GST at 18% (the India standard rate) from a $118 gross price finds Net Price = 118 / 1.18 = $100, so the GST Amount is 118 - 100 = $18.

Accurate GST computation matters whenever pricing, invoicing, or budgeting involves tax-inclusive or tax-exclusive figures. Below are practical scenarios where separating tax from base price prevents costly mistakes.

• Retail pricing: Setting shelf prices by adding GST to wholesale cost: a supplier cost of 85.50 at a 10% rate confirms the customer-facing price of 94.05.
• Invoice preparation: Separating the tax component from a lump-sum payment received: extracting GST from the total invoice amount determines the net revenue and the GST payable to the tax authority.
• Freelance and consulting: Quoting clients a GST-inclusive rate by adding tax to the desired take-home fee: a freelancer charging 150 per hour at 10% GST quotes 165 per hour.
• Import and export: Determining the landed cost of goods by adding the destination country's GST rate to the declared customs value, switching the rate to match the importing jurisdiction.
• Accounting reconciliation: Verifying GST amounts on supplier invoices by extracting the tax from each line item total and comparing the result to the stated tax amount on the document.
• Budget forecasting: Estimating annual GST liability by computing the tax on projected quarterly revenue figures, then multiplying the single-period GST amount by the number of periods to forecast the total obligation.
• E-commerce platforms: Displaying both tax-inclusive and tax-exclusive prices on product pages by adding GST at the applicable rate to the base product cost.
• Cross-border comparison: Comparing effective prices across countries with different GST rates by toggling the same base price between 5%, 10%, 15%, and 18% to see how the final cost changes by jurisdiction.