Position size calculator

How this is calculated

No hidden model and nothing fitted to data. Every figure on this page comes out of these lines, applied to the numbers you typed.

risk budget      = account size × risk %
stop distance    = | entry − stop |
risk per lot     = stop distance × units per lot
lots             = floor( risk budget ÷ risk per lot )
units            = lots × units per lot
position value   = entry × units

The other three

Frequently asked questions

How do I calculate position size from a risk percentage?

Multiply your account balance by the percentage you are willing to lose to get a risk budget in currency. Divide that by the distance between your entry and your stop, multiplied by the number of underlying units in one lot. On a $50,000 account risking 1%, the budget is $500; with a stop $2.50 away on a stock where one lot is one share, that is 200 shares.

Why does the calculator round down instead of up?

Rounding up would risk more than the percentage you stated, which defeats the purpose of sizing at all. Rounding down leaves part of the budget unused, and the calculator shows you exactly how much so the rounding is visible rather than silent. Fractional sizes are only allowed where the instrument genuinely trades in fractions, which here means spot crypto and forex.

Does this handle Indian F&O lot sizes?

Yes, and it is the main reason the tool exists. Indian derivatives trade in fixed lots — a Nifty lot is a fixed number of index units, and stock futures lots differ per underlying — so the units per lot multiplies both your position value and your risk. Type a symbol and the lot size fills in; the field stays editable because the exchanges revise these, and your broker's contract master is the number that governs.

What if my risk budget is smaller than one lot?

The calculator says so explicitly instead of quietly answering zero. It tells you what a single lot would risk on its own, and what percentage of your account that represents at the stop distance you entered. That is a common and entirely normal outcome for a smaller account looking at index derivatives.

Do I need to enter whether I am long or short?

No. The direction follows from the prices: a stop below the entry is a long, a stop above it is a short, and there is no third possibility. Asking for it separately would only add a field that could contradict the numbers you already typed.

Is any of this stored or sent anywhere?

Your figures, no. Every calculation runs in your browser: account sizes, entry prices and stop levels are never posted to a server, never stored and never logged, and closing the tab discards them. A free account is needed to open the calculator, and the site counts that a page was opened so it knows which tools get used — but that request carries a page name and nothing else. There is no analytics event carrying your account balance because there is no request that could hold one.