The short answer
Many US freelancers land somewhere around 15-30% of gross income. Where you fall depends on your profit, filing status and state. The "set aside 30%" rule of thumb is safe for most people but ties up cash you may not need to. Lower earners often need closer to 10-15%, and high earners in high-tax states can need more than 35%.
What you're actually saving for
1. Self-employment tax: about 14.1% of profit
This is Social Security and Medicare, which an employer would normally split with you. The rate is 15.3% on 92.35% of your net profit, which works out to about 14.13% of profit. The 12.4% Social Security part stops at $184,500 of earnings in 2026. The 2.9% Medicare part has no cap. It applies once your net SE earnings reach $400.
2. Federal income tax: your bracket, after deductions
First, half of your SE tax comes off your income. Then the 2026 standard deduction ($16,100 single, $32,200 married filing jointly). Then usually a 20% qualified business income (QBI) deduction. What's left is taxed at 10%, 12%, 22% and so on. That's why your average rate is lower than your top bracket.
3. State income tax
This varies a lot, from 0% in states like Texas and Florida to over 9% at higher incomes in states like California. Enter a rough effective rate. The calculator applies it to your adjusted gross income.
A simple system that works
Open a separate savings account. Each time a client pays you, move your set-aside % into it. Then pay your quarterly estimated taxes from that account. For 2026, the remaining due date is January 15, 2027 (for Sep-Dec income).
Why % of gross and not % of profit?
You know your gross the moment a payment lands. Your profit is only clear at year-end. So the % here is of gross income and already accounts for your expected expenses.