12 free tools · no signup
Free invoice calculators and small-business tools
Calculate dates, fees, deposits, billing amounts, pricing, and margins with transparent formulas. Each result is ready to carry into a quote, invoice, credit note, or payment conversation.
Invoice Due Date Calculator
Enter the invoice date and the number of calendar days in your payment term. The calculator returns the exact due date you can place on the invoice.
Open calculatorInvoice Late Fee Calculator
Estimate a simple late fee from an overdue invoice balance. Use only a rate and fee allowed by your signed terms and applicable requirements.
Open calculatorInvoice Deposit Calculator
Choose a project or order total and deposit percentage. The calculator shows the amount to invoice upfront and the balance that remains.
Open calculatorInvoice Discount Calculator
Calculate a percentage discount before tax and see the savings and discounted subtotal you can place on the invoice.
Open calculatorInvoice Sales Tax Calculator
Enter the taxable subtotal and the rate that applies to your transaction. The tool calculates the sales-tax amount and total after tax.
Open calculatorHourly Invoice Calculator
Turn tracked billable hours into an invoice total. Add reimbursable expenses and an optional verified tax rate.
Open calculatorProrated Invoice Calculator
Calculate a simple daily proration for a partial subscription, retainer, rent period, or recurring service.
Open calculatorMarkup Calculator
Enter your cost and markup percentage to calculate the selling price, gross profit, and resulting margin.
Open calculatorProfit Margin Calculator
Enter revenue and direct cost to calculate gross profit, gross margin, and the share of revenue consumed by cost.
Open calculatorBreak-even Calculator
Find the number of units or billable packages needed to cover fixed costs at the price and variable cost you enter.
Open calculatorPayment Processing Fee Calculator
Estimate the processing fee and net amount from a payment. You can also see the gross charge needed to receive a target amount after the entered fee.
Open calculatorRetainer Utilization Calculator
Track how much of a time-based retainer has been used and estimate any overage beyond the included hours.
Open calculatorTransparent arithmetic
Check the number, then show the customer
Every calculator displays its formula and the components of the result. Use it to verify a due date, price, deposit, discount, late fee, tax amount, or profitability assumption before that number reaches a customer.
The tool does not choose the commercial or legal rule for you. Enter the rate and method already supported by your agreement, records, and any applicable requirements.
A reliable calculation starts with
- The amount or cost before adjustments
- The exact rate or payment term being applied
- A formula that matches the signed agreement
- A result rounded consistently with the invoice
- A short explanation the customer can verify
Invoice calculator questions
Are the Invoity calculators free?
Yes. Every calculator on this page is free to use without an account. The calculation runs in your browser and the result can be carried into the relevant invoice, quote, estimate, or credit note.
Do these calculators determine tax or legal requirements?
No. They perform the arithmetic described on each page. You are responsible for entering the correct rate, term, fee, and cost treatment for your transaction.
What is the difference between markup and margin?
Markup compares gross profit with cost. Margin compares gross profit with selling price. Because the denominators differ, a 25% markup does not produce a 25% margin.
Can I use a calculated result in an invoice?
Yes. Open the related document generator after checking the result, then enter the amount, date, tax, discount, fee, or other value in the appropriate field.
Calculation done? Build the document.
Move the result into a live invoice, quote, estimate, receipt, purchase order, credit note, or another financial document.
Create a document