About PosSize

PosSize is a free toolkit of trading calculators built to help traders make faster, more disciplined decisions. Every tool runs entirely in your browser — no signup, no account, no paywall, and nothing you type ever leaves your device.

Who built this

PosSize is built and maintained by Grace Shin, a software engineer — not a professional trader or financial advisor. Every calculator implements standard, publicly documented trading formulas (the same math you'd find in a broker's help center or a finance textbook); PosSize's job is to implement them correctly, show the formula in the open, and keep the tool fast and free. That's the trust model here: not personal trading track record, but formulas you can check yourself and results you can verify by hand.

Why we built it

Most blown-up trading accounts share one root cause: poor risk management. Traders enter positions that are too large, ignore their stop distance, or misjudge leverage and margin. Good calculators fix this in seconds — but the ones online are often cluttered, signup-gated, or hidden behind broker funnels. We wanted clean, fast, accurate tools that anyone can use immediately.

What we offer

Our calculators cover the full lifecycle of a trade — sizing a position for a fixed risk, screening risk/reward, projecting compound growth, computing profit and loss, and handling forex pip value and margin. Each tool is paired with a plain-English explanation, the underlying formula, and a worked example.

Our principles

• Free and open access. No accounts, no limits, no dark patterns.
• Privacy by default. Calculations happen locally; we never see your numbers.
• Accuracy and transparency. We show the formula behind every result.
• Correctable. Found an error in a formula or a worked example? Tell us — see the contact page— and we'll fix it.

Ready to start? Explore the full set of calculators or reach out via our contact page.