A practical guide to estimating income tax before you file
An income tax calculator helps you see taxable income, tax by band, and the difference between your effective rate and your marginal rate. For U.S. federal tax, start with the IRS federal income tax rates and brackets and the IRS 2026 inflation adjustments. For other countries, use the jurisdiction pages linked above so the bands match local law.
Self-employed people in the United States often report profit on IRS Schedule C (Form 1040) and pay IRS self-employment tax page in addition to income tax. IRS estimated tax guidance explains when you should pay during the year so you are not surprised at filing time.
How this free tax calculator works
Choose a country or stay on this page to upload a statement for an AI-assisted U.S. estimate. You can also open a country page and type your own income and deductions. Brackets are editable so you can match a later official table.
The IRS Publication 334, Tax Guide for Small Business is the official small-business tax guide if you need to check which expenses are deductible. This website is a planning aid. It is not tax advice and it does not file a return.
Official sources we use to explain the numbers
United States: IRS federal income tax rates and brackets, IRS 2026 inflation adjustments, IRS estimated tax guidance, IRS Schedule C (Form 1040), and IRS self-employment tax page.
United Kingdom: HMRC Income Tax rates and Personal Allowances. Nigeria: Nigeria Revenue Service (NRS), Rev360 taxpayer self-service, and the Joint Revenue Board 2026 Personal Income Tax Guidelines. Germany: German Income Tax Act (EStG). France: service-public.fr income tax barème and impots.gouv.fr.