Invoice Calculator (Subtotal, Discount, Tax)
Calculate an invoice’s grand total in the correct order — subtotal, then discount, then tax (GST) on the discounted amount, then shipping — with every line shown.
Invoice Details
GST slabs: 5, 12, 18, 28%
Grand Total
₹59,000
Taxable ₹50,000 + tax ₹9,000
Subtotal
₹50,000
Discount
− ₹0
Tax @ 18%
₹9,000
Grand Total
₹59,000
How It Works
Getting an invoice total right means applying the components in the correct order, which this calculator does for you. It starts with the subtotal (the value of the items), then subtracts any discount to get the taxable amount. Tax — GST in India — is charged on that discounted taxable amount, not on the original subtotal, which is why the sequence matters: discounting first legitimately lowers the tax due. Finally, shipping or other charges are added to reach the grand total. The calculator breaks out each figure — the discount amount, the taxable value, the tax, and the final total — so the invoice is transparent and reconciles cleanly. Enter your subtotal, a discount percentage, your applicable GST rate, and any shipping, and it produces a clear, correct total you can use for quotes and billing.
Formula
Discount = Subtotal × discount%. Taxable = Subtotal − Discount. Tax = Taxable × tax%. Grand total = Taxable + Tax + Shipping.
Frequently Asked Questions
In what order are discount and tax applied on an invoice?
Discount first, then tax. The discount reduces the subtotal to a taxable amount, and tax (GST) is charged on that discounted amount. Shipping is added last, after tax.
Is tax charged before or after a discount?
After. Tax applies to the discounted (taxable) amount, so a discount also reduces the tax payable. Charging tax on the full pre-discount price would overcharge the customer.
Is shipping taxed on an invoice?
It depends on local rules and how shipping is billed. This calculator adds shipping after tax for simplicity; if shipping is taxable in your case, include it in the subtotal instead.
What GST rate should I use?
Use the slab applicable to your product or service — commonly 5%, 12%, 18% or 28% in India. Enter it as the tax rate; the calculator applies it to the taxable amount.
Can I use this for quotes and estimates?
Yes — it is ideal for building quotes. Adjust the subtotal, discount, tax and shipping to see the client’s total instantly, then copy or share the breakdown.