About Us

Building better financial tools for US and international stock investors.

Why we built this

If you've ever tried to calculate how much tax you owe after a successful year in the stock market, you've probably realized how incredibly confusing the US tax system can be.

Most basic capital gains calculators are dangerously simple. Because the IRS uses a "tax-stacking" mechanism, your investment profits sit directly on top of your standard W-2 job salary. If a calculator doesn't ask for your regular employment salary, it will determine your marginal brackets incorrectly, leaving you with an unexpected debt to the IRS in April.

Furthermore, navigating the differences between short-term capital gains (taxed at ordinary income rates) and long-term capital gains (taxed at preferential lower rates) requires exact calculation, especially when factoring in your filing status (Single vs. Married Filing Jointly).

Finally, many platforms leave out advanced rules like the Net Investment Income Tax (NIIT) which adds a 3.8% tax on high earners, or the unique state-level treatments of capital gains. We built this tool to dynamically map these complex layers instantly.

The N01 Labs Difference

The US Stock Tax Calculator is a proud product of N01 Labs, an independent software development company specializing in micro-SaaS financial utilities.

N01 Labs operates a little differently than traditional tech companies. We are a micro-studio driven by a single human founder working in close collaboration with advanced AI models. This unique human-AI partnership allows us to write highly optimized code, design intuitive user interfaces, and deploy premium web applications faster and more efficiently than ever before.

Our Promise

Accuracy: We use the exact 2026 IRS federal marginal tax brackets, correctly calculate preferential long-term capital tiers, enforce the $3,000 ordinary income loss-deduction limit, and factor in state-specific standard deductions.
Privacy: We don't save your financial numbers, we don't ask for your email to see your results, and we don't sell your data.
Speed: Built on modern web technologies, our calculator does the heavy lifting instantly right in your browser.

Get in Touch

Whether you have a feature request, spotted a bug, or just want to say hello, we read every single message.

Email us at: contact@n01labs.com