Position Size Calculator
Position sizing is the one risk control you fully decide before the trade. Enter your capital, how much of it you are willing to lose on this trade, and your stop loss distance — this tells you exactly how many shares or lots to buy so a loss costs what you planned, not what the market decides.
Free to use — no sign up required
Also searched as: lot size calculator, Nifty position size calculator, Bank Nifty quantity calculator, risk per trade calculator, intraday position sizing calculator
What is position sizing?
Position sizing is deciding how many shares or lots to trade, based on how much money you are prepared to lose if the trade fails. It is the opposite of how most people trade: rather than picking a quantity that feels right and discovering afterwards what it risks, you fix the loss first and let arithmetic set the quantity.
It matters more than entry timing. Two traders can take identical trades on the same chart and end the year in completely different places purely because one risked 1% per trade and the other risked 8%. Entries decide whether a trade wins; position size decides whether you survive the ones that lose.
How to use this position size calculator
- Enter your trading capital — the amount actually allocated to trading, not your total net worth.
- Set your risk per trade as a percentage. If you are unsure, start at 1%.
- Pick the instrument. Choose "Stock" for cash equity, or an index for F&O so the result is rounded to whole lots.
- Enter your entry price — the price you expect to be filled at.
- Enter your stop loss — the price at which the trade idea is proven wrong. Place it where the chart invalidates the setup, not where the loss feels tolerable.
The calculator instantly returns the quantity or number of lots, plus what a stop-out actually costs at that size. If a single lot already exceeds your risk budget, it says so rather than quietly suggesting a size that breaks your rule.
The position size formula
Risk amount = Capital × Risk % Risk per unit = |Entry price − Stop loss price| Quantity = Risk amount ÷ Risk per unit Lots = floor(Quantity ÷ Lot size)Worked example: NSE stock
You have ₹1,00,000 and risk 1% per trade — ₹1,000 at stake. You enter at ₹1,500 with a stop at ₹1,470, so each share can lose ₹30.
| Step | Value |
|---|---|
| Risk amount (1% of ₹1,00,000) | ₹1,000 |
| Risk per share (1,500 − 1,470) | ₹30 |
| Quantity (1,000 ÷ 30) | 33 shares |
| Position value (33 × 1,500) | ₹49,500 |
| Actual loss if stopped out | ₹990 |
Worked example: Nifty options
Same ₹1,00,000 capital at 1% risk, so ₹1,000 at stake. You buy a Nifty option at ₹150 premium with a stop at ₹120 — ₹30 of risk per unit. ₹1,000 ÷ ₹30 = 33 units, but Nifty trades in lots of 65, and one full lot would risk ₹1,950. That is nearly double your budget, so the honest answer is zero lots: either widen the stop, accept a higher risk %, or skip the trade. This is the single most common way retail traders quietly over-risk on index options.
Current NSE index lot sizes
NSE revised index lot sizes effective 1 January 2026. SEBI requires contract value to stay inside a prescribed band, so these change whenever an index moves far enough — always confirm against the live contract.
| Index | Lot size |
|---|---|
| Nifty 50 | 65 |
| Bank Nifty | 30 |
| Fin Nifty | 60 |
| Midcap Nifty | 120 |
What risk percentage should you use?
Most professionals risk 0.5% to 2% per trade. The reason is survivability rather than caution — losing streaks are normal, and the table below shows what ten consecutive losses do at each level.
| Risk per trade | After 10 losses | Gain needed to recover |
|---|---|---|
| 1% | 90.4% left | 10.6% |
| 2% | 81.7% left | 22.4% |
| 5% | 59.9% left | 67.0% |
| 10% | 34.9% left | 186.8% |
Same strategy, same losing streak. At 1% it is a dull month; at 10% the account may never recover.
Why lots are rounded down
Index F&O trades in fixed lots, so the exact quantity is rarely available. This calculator always rounds down. Rounding up would quietly break the risk rule you just set, and the trades where that matters most are exactly the ones that hurt.
Common position sizing mistakes
- Sizing by capital instead of risk. "I'll put ₹50,000 into this" says nothing about what you lose if it fails. A tight stop and a wide stop on the same ₹50,000 are entirely different trades.
- Moving the stop to fit the size. If the quantity you want needs a tighter stop than the chart justifies, the answer is a smaller quantity, not a worse stop.
- Increasing risk to recover losses. Doubling down after a drawdown is the fastest route from a recoverable loss to an unrecoverable one.
- Ignoring correlation. Five 1% positions in five banking stocks is not 1% risk five times — it is closer to one 5% bet on the banking sector.
- Forgetting gap risk. A stop is an instruction, not a guarantee. Overnight gaps and circuit moves can fill you well below it.
What this calculator does not include
Sizing here is on price risk alone. Brokerage, STT and GST add a small amount to every loss — use the brokerage calculator to quantify it, especially if you scalp small moves where charges are a real share of the outcome. Margin requirements for F&O are also not modelled; your broker's margin may exceed the position value shown.
Frequently asked questions
Position size = (capital × risk %) ÷ (entry price − stop loss price). The numerator is the rupee amount you are willing to lose; the denominator is what one share loses if the stop is hit. Dividing one by the other gives the quantity at which those two numbers match.
A calculator tells you the plan. A journal tells you if you followed it.
TradeXJournal records every trade you take, tags the setup and the mistake, and shows you which of your setups actually make money. Free for 14 days, no card needed.
Related calculators
Browse all free trading toolsThese calculators are provided for information and education only. They are not investment, tax or financial advice. Charge rates and tax thresholds change — verify against your broker's contract note and a qualified professional before acting.