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About this tool
Find your true average buy price, live P&L, and break-even, plus a planner for averaging down the smart way.
The Stock Average & Break-Even Calculator takes every buy lot in a position and returns the true weighted average price — total amount invested divided by total shares held — along with live unrealised profit and loss and the break-even price once round-trip charges are included. Its averaging-down planner solves the other direction: give it a target average and it computes the exact share count needed using shares = Q × (A − T) ÷ (T − P), or give it a budget and it shows the average you would end up with. It is for retail investors adding to an existing holding who want the arithmetic settled before they place the order.
Open Stock Average & Break-Even Calculator on AltFTool — it loads instantly in your browser.
Under Your buy lots fill Lot 1 quantity and Buy price (₹), pressing Add another lot for each further tranche, then set Current market price (₹) and Round-trip charges (%)
In Averaging planner switch to Reach a target average and enter Target average price (₹), or to I have a budget of ₹X and enter Budget for this buy (₹)
Position summary reports the Weighted average price with Total quantity, Total invested, Portfolio value and Break-even price, while the planner returns Buy N shares with Cost required, New total quantity and Achieved average; Copy summary copies the position and Reset clears the lots
It applies your round-trip charge rate on both the buy and the sell side, so the price you actually need to exit flat is shown separately from your average cost.
Buying at the market price can never pull your average below that price, and the planner says so explicitly with the reachable range instead of returning a nonsense share count.
Your buy lots, market price and charge rate are saved locally, so you can add each new tranche as it happens rather than retyping the whole position every time.
Divide the total amount invested by the total number of shares — never average the prices themselves, because that ignores lot size. Buying 100 shares at ₹300 and 400 at ₹200 gives ₹110,000 over 500 shares, an average of ₹220, not the ₹250 a simple mean would suggest.
Use shares = Q × (A − T) ÷ (T − P), where Q is your current quantity, A your current average, T the target average and P the price you will buy at. With 100 shares averaging ₹250 and a market price of ₹200, reaching a ₹220 average takes 150 more shares — one and a half times your existing position, which is why averaging down gets expensive fast.
A little above your average, because charges apply on both the purchase and the sale. At a 0.3% round-trip rate the break-even sits about 0.60% above your average — an average of ₹200 needs roughly ₹201.20 to exit flat — and the gap widens proportionally as your charge rate rises.
It lowers your average price, but only by increasing your exposure to a position that has already moved against you — the arithmetic always works, the investment case may not. Decide whether you would buy the stock today at this price with fresh money before using the planner, and treat the output as arithmetic rather than investment advice.
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