Invoice Generator

Invoice generation creates structured billing documents by organizing client information, line items, and payment details into a professional format. This tool uses reactive calculations to automatically compute subtotals, taxes, and final amounts as you input data, eliminating manual arithmetic errors common in spreadsheet-based invoicing.



When you enter line items with quantities and rates, JavaScript performs real-time multiplication (quantity × rate) for each item, then sums all line totals for the subtotal. Tax calculations apply your specified percentage to the subtotal (subtotal × tax rate / 100), and the final total adds tax to the subtotal. Using Svelte's $derived reactivity, all calculations update instantly when any value changes.



The invoice layout uses HTML and CSS to create a print-ready document following standard invoice formatting conventions: header with business details, recipient information, itemized services table, and payment summary. The print function triggers the browser's native print dialog, allowing you to save as PDF or send to a printer while hiding web interface elements for clean output.

1. Freelancer Billing
Freelancers (designers, developers, writers, consultants) send invoices to clients for completed work. Add hourly rates or project-based fees, include multiple line items for different services, apply appropriate tax rates. Professional invoices improve payment speed and maintain business credibility. Track invoice numbers sequentially for accounting records.



2. Small Business Operations
Small businesses without dedicated accounting software need quick invoice generation for products or services. Create invoices for retail sales, service appointments, contract work, or wholesale orders. Automatic calculations prevent pricing errors. Professional presentation encourages prompt payment and reduces billing disputes with clear itemization.



3. Recurring Service Billing
Service providers with regular clients (cleaners, maintenance, subscriptions) generate monthly invoices for ongoing work. Copy previous invoice details, update invoice number and date, adjust quantities or rates as needed. Consistent invoice formatting helps clients recognize and process payments quickly, improving cash flow.



4. Project-Based Work
Consultants and contractors working on multi-phase projects invoice upon completion of milestones. Break down complex projects into discrete line items showing progress and deliverables. Clear itemization justifies charges and helps clients understand value received, reducing payment delays or disputes over scope.



5. Quick Payment Requests
When immediate payment documentation is needed (deposit requests, partial payments, emergency services), generate invoices on-the-spot without waiting to access office software. Email or print invoices directly from the tool. Perfect for mobile professionals who need to invoice clients during site visits or consultations.

• Use sequential invoice numbering: Maintain consistent numbering (INV-001, INV-002) for accounting and tax purposes. Sequential numbers help track revenue, identify missing invoices, and prevent duplicate payments. Many jurisdictions require continuous invoice numbering for tax compliance.



• Set clear payment terms: Specify due dates (Net 15, Net 30) and accepted payment methods in the notes section. Clear terms reduce payment delays and set client expectations. Include late payment penalties if applicable. Many businesses use "Due upon receipt" for small invoices or "Net 30" for established clients.



• Itemize services in detail: Break down charges into specific line items rather than single lump sums. "Web Development - Homepage Design, 8 hours @ $100/hr" is better than "Web Development - $800." Detailed itemization justifies costs, reduces disputes, and helps clients understand value provided.



• Double-check tax calculations: Verify tax rates match your jurisdiction's requirements. Some regions have multiple tax rates (state + local), tax exemptions for certain services, or different rates for products vs. services. Incorrect tax invoicing creates legal and accounting complications.



• Save invoice copies before printing: Use browser print-to-PDF to save digital copies before printing. Maintain invoice archives for accounting, tax filing, and client history. Organized invoice records simplify year-end taxes, audit preparation, and resolving payment disputes.



• Professional presentation matters: Include complete business contact information, professional email addresses, and business logo if possible. Well-formatted invoices project credibility and professionalism, encouraging timely payment. Sloppy invoices suggest disorganized business practices.



• Review totals before sending: Always verify subtotal, tax, and final total calculations before issuing invoices. While automatic calculations reduce errors, input mistakes (wrong quantity or rate) still occur. A quick review prevents embarrassing corrections or client confusion later.