For pass-through entities, the amount of tax you pay doesn’t change. It’s the same amount as if you were operating without an LLC.
Meaning, the business income from your LLC “flows through” to your personal tax return. And then your income tax is based on the graduated rates set by the IRS, plus any flat-rate taxes like self employment tax. Check your personal income tax rate here: IRS Income Tax Rates for 2021.
Note: An LLC taxed as a C-Corporation pays entity-level taxes at the corporate tax rate. And the owners also pay personal income tax at their personal income tax rate. You can determine your corporate tax rate here: IRS: Publication 542.