9 calculators · document and reference tools
Free invoice tools and calculators
Choose a task first: calculate an amount, review a draft, prepare a document or read a guide. Each page explains its inputs, limits and next steps before you use the result.
By Invoodle · Updated
Calculators and guest PDF creation are available without signup. Optional hosted sharing, account and API features have separate data flows. Review each page’s inputs, calculation limits and sharing behavior before using a result.
Find the tool for the next step
Calculators, references and document workflows do different jobs. Use the label on each card to choose what you need; the guide and example pages help you review the wider billing context.
Tax calculators and code references
Choose the arithmetic for your tax context or review a classification starting point. Check the inputs and source notes on the individual page.
Calculator
VAT Calculator
Add VAT to a net price or remove included VAT using a checked rate.
Open VAT CalculatorCalculator
US Sales Tax Calculator
Add sales tax or reverse an inclusive total using your checked combined rate.
Open US Sales Tax CalculatorCalculator
Canada GST/HST Calculator
Add or reverse selected Canadian general-rate tax components on one amount.
Open Canada GST/HST CalculatorCalculator
GST Calculator
Add or remove GST using a checked rate, with illustrative tax-component breakdowns and rounding notes.
Open GST CalculatorCode reference
HSN & SAC Code Finder
Search a limited, source-linked classification reference. Review the actual supply and official code scope.
Open HSN & SAC Code FinderPricing, dates and currency scenarios
Explore your own assumptions about rates, margins, due dates, interest and conversion fees before preparing a document.
Calculator
Late Payment Interest Calculator
Estimate simple interest on one unchanged balance using checked dates and rates.
Open Late Payment Interest CalculatorCalculator
Freelance Rate Calculator
Explore hourly and day rates from your own income, costs and billable time.
Open Freelance Rate CalculatorCalculator
Discount & Margin Calculator
Compare discounts, markup, gross margin and a target selling price.
Open Discount & Margin CalculatorCalculator
Invoice Due Date Calculator
Calculate calendar-day payment dates, month-end terms and optional weekend adjustments.
Open Invoice Due Date CalculatorCalculator
Invoice Currency Converter
Estimate an invoice conversion at a checked rate, with assumed percentage and fixed fees.
Open Invoice Currency ConverterPrepare or review a document
Select the document purpose, review the details and keep an appropriate copy of the result.
Document workflow
Invoice Generator
Create an invoice PDF with agreed items and manually recorded payments. Review any existing draft before editing.
Open Invoice GeneratorDocument workflow
Quote Generator
Describe proposed work, quantities and prices before preparing the final invoice.
Open Quote GeneratorDocument workflow
Receipt Generator
Record money actually received, with reviewed items, dates and payment references.
Open Receipt GeneratorDocument workflow
Proforma Invoice
Prepare a preliminary document and review how it differs from a final invoice or payment receipt.
Open Proforma InvoiceDocument workflow
Rent Receipt Generator
Describe the rent period, parties and payment actually received, with the page’s document limits.
Open Rent Receipt GeneratorDraft review
Invoice Check
Review supported draft fields and amount checks, with the scope of each check explained.
Open Invoice CheckChoose a guide or worked example
Use a relevant example or checklist before deciding what belongs on your own document.
Guide directory
Invoice Guides by Profession
Compare ten profession guides covering projects, sessions, visits, supplies, events and trips.
Open Invoice Guides by ProfessionGuide directory
Country Invoice Guidance
Review country-specific invoice preparation and the editor’s documented field limits.
Open Country Invoice GuidanceWorked examples
Invoice Examples
Follow fictional worked invoices and compare the quantities, charges, payments and balances.
Open Invoice ExamplesCheck the inputs before using a result
- Choose the calculation or document purpose. Add-tax and tax-inclusive directions, a fixed package and hourly work, or an invoice and receipt answer different questions.
- Use the amount, rate, dates, quantity and fee basis you have checked for the actual task. Example inputs are illustrations. Read the selected page’s rounding method, review date and source notes where provided.
- Review what the result covers. An estimate does not determine tax treatment, classification, a contractual entitlement or a bank’s settlement amount.
- When preparing an invoice, review the existing draft, document mode, currency, items, tax, payments and required particulars. Opening the editor does not automatically import calculator figures.
The invoice editor has one document-level Tax adjustment and its own calculation order. Check the relevant page before copying numbers into a document, particularly for mixed treatments, discounts, rounding or a partial payment.
Understand copying, lookups and saved documents
The calculation pages run arithmetic in the browser. Explicit calculation-link actions can place inputs in a shareable URL. The currency converter’s optional reference-rate lookup contacts an external provider; review the source and update time on that page. Its estimate is not a bank quote or payment confirmation.
Guest drafts and saved documents use browser storage and do not automatically sync across devices. Regular document links contain an encoded copy; optional confirmed hosted sharing uploads an encrypted snapshot. Account and developer/API features have separate server-storage behavior. Review the storage and sharing explanation before using those features, and keep a PDF or independent backup.
Ready to prepare a bill? This directory’s invoice links open Invoice mode without importing a calculation or clearing existing items, notes or terms. Changing display currency changes formatting rather than converting existing item prices.
For layout choices, compare invoice template styles. For integration requirements, read the developer documentation and its account/API controls.
Questions about free invoice tools
Are these invoice tools free without signup?
The public calculators, reference pages and guest PDF document workflow do not require signup. Optional account, hosted-sharing and developer/API features have separate controls and requirements. The directory does not promise unlimited third-party services or automatic cloud backup.
How do I choose the right calculator or reference tool?
Start with the task: add or reverse a checked tax amount, compare a pricing scenario, calculate an agreed due date, estimate interest or review a currency conversion. HSN/SAC lookup is a limited classification reference, and Invoice Check reviews supported draft fields. Read the selected page’s input rules and limits before using its result.
Do the tools determine the correct tax rate or legal entitlement?
No. Example rates, dates and assumptions do not establish the treatment of your transaction or a right to charge interest. Check the relevant source notes, effective dates, agreement and applicable requirements. The general invoice editor has one document-level Tax adjustment, not per-line classification or specialist tax filing.
Does everything stay in my browser?
The calculation pages perform arithmetic in the browser, but optional actions have other data flows. The currency converter’s reference-rate lookup contacts an external provider. Calculation links can contain inputs; regular document links contain an encoded copy. Confirmed hosted sharing and account/API features use server services. Review each page and the Privacy explanation before sharing.
Are calculator results automatically added to an invoice?
Opening the invoice editor from this directory does not import a calculation or clear an existing draft. Review the document mode, currency, items, tax and payments yourself. Changing display currency does not convert existing item prices. A currency estimate is not a bank quote or payment confirmation.
Should I create an invoice, quote, receipt or proforma?
Use a quote to describe proposed work and prices, an invoice to record charges, and a receipt for money actually received. A proforma is preliminary and does not automatically become a final tax invoice or prove payment. Review the selected workflow’s limits and any local or recipient-specific requirements before issuing.