Position Size Calculator
Enter your capital, the share of it you're willing to lose, and your stop loss. You get the exact number of shares or F&O lots to buy, so a stop-out costs you that amount and not a rupee more.
By Hardik Vegad, founder of WealthGamma · Last updated
Shares to buy
Long111
- Money at risk if stop loss hits
- ₹4,995
- Stop loss price
- ₹1,455
- Loss per share
- ₹45 (3.00%)
- Position value
- ₹1,66,500
- Profit at target
- ₹9,990
- Risk to reward
- 1 : 2
- Win rate needed to break even
- 33.3%
Excludes brokerage, STT and slippage. A gap past your stop loss can cost more than the amount shown.
What is position sizing?
Position sizing is deciding how many shares to buy based on how much you can afford to lose, not on how much you like the stock. You pick the loss first. The quantity follows from your stop loss.
Two trades with the same capital can need very different sizes. A stock with a tight stop lets you buy more. A stock with a wide stop needs fewer shares for the same rupee risk.
What is the position size formula?
Risk amount = Capital × Risk %
Loss per share = Entry price − Stop loss
Position size = Risk amount ÷ Loss per share
Round the result down to a whole share. Rounding up would put you over your risk limit.
How many shares should I buy? A worked example
With ₹5,00,000 of capital, 1% risk per trade, an entry at ₹1,500 and a stop loss at ₹1,455, you buy 111 shares. Here's how that number comes out:
- Risk amount: ₹5,00,000 × 1% = ₹5,000
- Loss per share: ₹1,500 − ₹1,455 = ₹45
- Position size: ₹5,000 ÷ ₹45 = 111.1, rounded down to 111 shares
You buy 111 shares for ₹1,66,500. If the stop loss hits, you lose ₹4,995, just under 1% of your capital. With a target of ₹1,590, the trade makes ₹9,990: twice what it risks.
How do you calculate position size for a short trade?
For a short trade, your stop loss sits above the entry price. The formula doesn't change: loss per share is the gap between the two, whichever way it runs. Short at ₹800 with a stop at ₹824 and ₹5,000 of risk, and you sell ₹5,000 ÷ ₹24 = 208 shares.
In the cash market, a short has to be closed the same day. Carry a short overnight only through futures or options.
How do you calculate position size for F&O lots?
Futures trade in fixed lots, so you size in lots, not units. Multiply the loss per unit by the lot size to get the loss per lot. Divide your risk amount by that and round down.
With ₹5,000 of risk, a lot size of 50 and a 40-point stop, one lot risks ₹2,000. You can take 2 lots (₹4,000 at risk). If one lot alone risks more than your limit, the honest answer is zero lots: widen your capital, tighten the stop, or skip the trade.
Lot sizes change when NSE revises them, so check the current contract specs before you trade.
How much should you risk per trade?
Most traders keep it between 0.5% and 2%. The reason is losing streaks. Every strategy has them, and a higher risk % turns a normal bad run into a hole that takes months to climb out of.
| Risk per trade | After 10 losses in a row | After 20 losses in a row | Gain needed to recover |
|---|---|---|---|
| 0.5% | ₹4,75,555 | ₹4,52,305 | 10.5% |
| 1% | ₹4,52,191 | ₹4,08,953 | 22.3% |
| 2% | ₹4,08,536 | ₹3,33,804 | 49.8% |
| 5% | ₹2,99,368 | ₹1,79,243 | 179.0% |
Starting capital ₹5,00,000. Each loss is the risk % of what's left. Recovery is from the 20-loss balance.
What win rate do you need to break even at 1 : 2?
At 1 : 2 risk-reward you need to win 33.3% of your trades to break even. The formula is 1 ÷ (1 + reward multiple). Each win makes twice what a loss costs, so one win in three covers two losses.
A 1 : 1 trade needs you to be right more than half the time. A 1 : 3 trade needs just 25%.
What does position sizing not account for?
Position sizing caps what you lose if your stop loss fills at your price. Four things sit outside it:
- Charges. Brokerage, STT, exchange fees and GST come on top of your loss.
- Gaps and slippage. A stock can open below your stop loss, and the fill comes at that price.
- Where to put the stop. The calculator sizes the trade; the stop loss is your call.
- Tax. Intraday profit is taxed as business income. Read how intraday trading tax works in India.
Frequently asked questions
How do you calculate position size?
Divide the money you're willing to lose by the loss per share. Risk amount = capital × risk %. Loss per share = entry price minus stop loss. Round the answer down.
What percentage of capital should I risk per trade?
Most traders risk 0.5% to 2% of capital per trade. At 1%, ten straight losses leave you with about 90% of your capital.
Does position size change for intraday trading?
The formula is the same. Leverage only raises how much you can buy. For 5× intraday, set Max position size to 500%.
Can I use this calculator for short selling?
Yes. Set Direction to Short and put the stop loss above your entry price.
How is position size calculated for F&O?
Multiply the loss per unit by the lot size to get the loss per lot, then divide your risk amount by it. Round down to whole lots.
Can I enter the stop loss in points or percent?
Yes. Switch the stop loss to ₹ points (how far price can move against you) or %. The calculator works out the stop price.
Why is my actual risk lower than the risk I entered?
You can't buy part of a share or part of a lot, so the quantity is rounded down. The leftover is risk you didn't take.