There are several effective tax rate calculators available online that can estimate your federal income tax, calculate your effective and marginal tax rates, and consider your income, filing status, deductions, and credits. Notably, NerdWallet offers a free income tax calculator where you input your income, age, and filing status to estimate your tax refund or bill. This calculator also provides an effective tax rate, marginal tax rate, and takes into account deductions like retirement contributions and tax credits.

SmartAsset provides a federal income tax calculator for 2024-2025 that helps calculate federal, state, and local taxes considering income tax brackets by filing status, with a clear explanation of how marginal tax rates apply.

TaxAct also has a free tax bracket calculator useful for estimating your federal tax bracket and total tax based on your salary or self-employment income.

Other specialized calculators include the Marginal Tax Rate Calculator from Ameriprise that estimates your marginal and average tax rates and tax bracket, suitable for planning how tax impacts investments or unexpected income.

If interested, I can guide on how to use one of these calculators or summarize their instructions for calculating your effective tax rate.