About StopSize

The problem this solves

Position sizing is the one piece of trading that is pure arithmetic, and it is the piece most people get wrong. Not because the formula is hard — it is one division — but because the three numbers that feed it live in three different places. Your account balance is in your broker. The percent you are willing to risk is a decision you made once and half remember. The distance to your stop is on the chart. Somewhere between those three, a position gets bigger than it was meant to be.

Most tools built for this hand you a number and stop. You type four values into a box and a fifth value appears, with no working shown and no way to tell whether it is right. If the answer surprises you, there is nothing to check.

StopSize shows the arithmetic. Every result on the calculator lists the steps that produced it — the risk in currency, the distance to the stop, the division that turns one into the other — so you can follow it, catch a typo, and learn the shape of the calculation instead of trusting it.

What is here

• A risk calculator for position size, exposure, profit and loss and risk/reward, on long and short trades, with dedicated versions that speak the language of forex, futures and crypto.
• A dictionary of 135 terms, written in plain English, with a worked example on every entry and a live calculator embedded in many of them.
• 9 long-form guides that work a single subject all the way through with real numbers.
• A trading journal that computes win rate, average R, profit factor and drawdown from trades you log yourself.
• 24 entries of market history, each one a crash or a crisis with the risk lesson that outlived it.

Who writes this

StopSize is written, built and maintained by Javier Sánchez Ros, independently. Every guide, every dictionary entry and every calculator on the site is his work, and corrections come to him directly. There is no editorial team, no sponsor and no parent company, and the site sells nothing — no course, no signal service, no premium tier, no affiliate links to brokers. That matters more than it sounds: a site that earns a commission when you open a brokerage account has a reason to tell you to trade more, and this one does not.

Everything on the site is written from scratch for it. Nothing is syndicated, reposted or spun from another publication. Where a definition is contested — and in trading plenty are — the entry says so rather than picking one and pretending it is settled.

How the numbers are worked out

Every formula the calculators use is printed on the page that uses it, so nothing is hidden in code you cannot see. Futures contract specifications — tick size and tick value for ES, NQ, MES, MNQ, YM, RTY, CL and GC — are the real CME figures, and the point value is derived from them at runtime rather than stored separately, so the two can never drift apart and quietly disagree.

Crypto prices come from CoinGecko. Foreign exchange rates are the European Central Bank reference rates, which are published once each working day — the site labels them as such rather than dressing a daily figure up as a live one.

Every page that shows a market number also shows when that number was last refreshed. If it is an hour old, it says so.

What this site will not do

• No real-time stock prices. Displaying live equity quotes requires a licence from the exchange that owns them. There is no such licence here, so those prices are absent rather than delayed and presented as current.
• No advice, no calls, no signals. Nothing here tells you what to buy, when to buy it, or what a market will do next. The calculators answer “how much”, never “whether”.
• No claims about returns. Position sizing does not make a losing strategy profitable. It controls the size of the losses, which is a different and much smaller promise.
• No account, and no upload. Your journal entries are stored by your own browser, on your own device. They are never transmitted anywhere, because there is no server here to transmit them to.

Corrections

A wrong tick value or a mistyped formula is worse than no tool at all, because it is wrong in a way that looks right. If you find an error in a calculation, a definition or a contract specification, send it to the contact page and it gets fixed. Corrections take priority over new features.

What this is not

This website provides educational information only. It is not financial, investment, or trading advice. Trading carries risk, including the risk of losing more than you deposit on leveraged products. Nothing on this site is a recommendation to buy or sell anything.