The math should never be the reason a trade fails.

Why we built this

Walk onto any professional trading desk and you'll notice something: before anyone talks about direction, they talk about size. How much is at risk if this is wrong? What does the account lose on a stop-out? Is the reward worth it? Retail traders are handed charting platforms with a thousand indicators, but the four calculations that actually protect capital are usually buried, paywalled, or wrapped in sign-up forms designed to harvest email addresses.

We wanted the opposite: a fast, quiet page that answers the pre-trade questions in seconds and asks nothing in return. No account. No tracking of the numbers you enter. No "premium" tier holding the useful features hostage. Just the arithmetic, done correctly, presented clearly.

How the calculators are built

Every formula on SmartTrader.io is implemented from first principles and documented on the page that uses it:

• Position sizing uses fixed-fractional risk — dollar risk divided by per-share risk, with share counts rounded down so you never exceed your planned risk.
• Risk/reward validates trade direction (long vs. short) so an impossible setup is flagged before it produces a misleading ratio.
• Compound interest uses true month-by-month iteration with end-of-month contributions rather than a closed-form approximation, so the chart and the totals always agree to the cent.
• Dollar-cost averaging converts your expected annual return into an effective per-period rate, so weekly, bi-weekly and monthly plans with the same annual return compound consistently.

Calculations run entirely in your browser using standard JavaScript number formatting for US-dollar output. If you find a discrepancy of even a cent against your own spreadsheet, tell us — we treat accuracy reports as our highest-priority inbox.

What we will never do

• Store, transmit or sell any figure you type into a calculator.
• Run analytics without asking first — measurement happens only if you consent, and never touches the numbers you enter.
• Tell you what to buy or sell. These are measurement tools, not advice — see the disclaimer.
• Put the core calculators behind a login or a paywall.