How to Use the Invoice Calculator

Add line items — each with a description, quantity, and unit price.
Optionally apply a discount (as a percentage of the subtotal).
Enter a tax rate if applicable (e.g., 8.5 for 8.5% sales tax).
The subtotal, discount amount, tax amount, and grand total update instantly.
Click Download CSV to save the full calculation.

How Invoice Totals Are Calculated

Understanding the calculation order ensures accurate invoicing:

Line item total: Quantity × Unit price for each row.
Subtotal: Sum of all line item totals.
Discount: Applied to the subtotal. Discount amount = Subtotal × (Discount% ÷ 100).
Discounted subtotal: Subtotal − Discount amount.
Tax: Applied after discount. Tax amount = Discounted subtotal × (Tax% ÷ 100).
Grand total: Discounted subtotal + Tax amount.

Freelancer and Small Business Tips

Itemize your work: Break work into clear line items (e.g., "Design mockup — 3 hrs @ $85/hr" rather than just "Design work"). This reduces disputes and clearly communicates your value.
Include tax when required: If you're registered for sales tax or VAT, apply it after any discounts. Tax is always calculated on the taxable amount, not the pre-discount total in most jurisdictions.
Use CSV as a record: Download and save CSVs for your invoicing records. They import easily into Excel, Google Sheets, or accounting software.
For formal invoicing: This tool calculates totals, but for professional invoices sent to clients, use dedicated invoicing software that includes payment terms, your business information, and legally compliant formatting.

Frequently Asked Questions

Is the discount applied before or after tax?

Discount is applied to the subtotal first. Tax is then calculated on the discounted subtotal. Formula: Total = (Subtotal − Discount) × (1 + Tax Rate). This is standard practice in most invoicing scenarios.

Can I save my invoice?

Click Download CSV to save all line items plus the calculated totals. The CSV can be opened in Excel, Google Sheets, or imported into accounting software.

Is this a full invoicing tool?

This is a calculator, not a full invoicing application. It helps you quickly calculate totals, apply discounts and tax, and export a summary. For sending formal invoices to clients, use dedicated tools like Wave, FreshBooks, Invoice Ninja, or QuickBooks.

How do I calculate hourly billing?

Enter the task as a line item with quantity = hours worked and unit price = your hourly rate. For example, Quantity: 4 hours, Unit Price: $75/hr = Line Total: $300. Add as many hourly tasks as needed.

Invoice Calculator