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Stock Average Calculator
Weighted-average buy price across lots, a target-average planner (how many to buy to reach ₹X), and true cost with charges. Accurate, instant and free — for India.
What these mean:
Purchase lots
Enter each lot — price per share and quantity bought.
Paste a spreadsheet selection — 2 columns: price per share, quantity. Existing lots are replaced.
What these mean:
Your blended buy price across 2 lots is ₹267 per share. You hold 300 shares with a total investment of ₹80,000. A lot held over 12 months qualifies as long-term — see the Capital Gains Tax Calculator for the tax on a sale.
Lot breakdown
Blended average
₹267
Weighted by quantity across 2 lots
A lot held over 12 months qualifies as long-term (LTCG). Use the Capital Gains Tax Calculator to estimate the tax when you sell.
How the weighted average and target-average are calculated
The average buy price is a weighted average — total invested divided by total quantity, so a larger lot pulls the average towards its price. The target-average planner reverses the arithmetic: given your holding and a price, it solves for the quantity to buy to reach a desired average. Results cross-checked against Groww.
Weighted average
avg = Σ(p·q) / Σq
avg = Σ(price×qty) / Σqty
- Total invested ÷ total shares held
- Weighted by quantity, not a plain mean of prices
Target-average solver
n = Q·(A−T) / (T−P)
n = Q × (A − T) / (T − P)
- Q, A= current qty & average
- P = buy price, T = target average
- Valid for averaging down when P < T < A
True cost (with charges)
Add brokerage / STT / GST
true_avg = (Σ(p×q) + charges) / Σq
- Folds brokerage, STT, GST, stamp, DP into the basis
- The real cost basis used for profit & tax
- 1Weighted average across two lots: 100 @ ₹250 + 200 @ ₹275 = (25,000 + 55,000) / 300 = ₹266.67 (matches Groww). The 200-share lot weighs twice as much, so the average sits closer to ₹275 than to the midpoint ₹262.50.
- 2Target average — how many to buy: Hold 100 @ ₹250, price now ₹200, want a ₹220 average: n = 100 × (250 − 220) / (220 − 200) = 150 shares. Check: (25,000 + 150×200) / 250 = 55,000 / 250 = ₹220 ✓. Buying 150 more shares at ₹200 pulls your blended average down to exactly the target.
Target mode needs P < T < A
Should I average down? The break-even recovery test
The arithmetic of averaging is trivial; the decision is not. Averaging down lowers your break-even price — but only by committing fresh capital and concentrating more of your money in one falling stock. The right lens is the recovery percentage: how far the price must climb for you to break even, before versus after averaging.
| Scenario | Average | Price now | Recovery to break even |
|---|---|---|---|
| Before averaging | ₹250 | ₹200 | +25% |
| After averaging to ₹225 | ₹225 | ₹200 | +12.5% |
Lowering the average from ₹250 to ₹225 halves the climb needed to break even (+25% → +12.5%) — but commits fresh capital and increases concentration risk in a stock that is already falling.
Lower break-even is not the same as a good bet
Charges and the LTCG/STCG split your average hides
A price-times-quantity average is not your real cost basis. Fold in brokerage, STT, GST on brokerage, stamp duty and DP charges and the true average rises — and that is the number that decides your profit and the capital-gains tax on a sale. Because each lot keeps its own purchase date, the holding-period split (long-term vs short-term) is also per-lot, not blended.
- 1Add charges for the true cost: true_avg = (Σ(price×qty) + total_charges) / Σqty. In India that is brokerage, STT (~0.1% delivery), GST 18% on brokerage, stamp duty and DP charges — all estimates; always check your broker's contract note for the exact figures.
- 2Split by holding period (the 12-month line): Shares held more than 12 months are long-term (LTCG); 12 months or less are short-term (STCG). Averaging down starts a fresh 12-month clock on the new lot, so a single position can be part long-term, part short-term when you sell.
Cross-links
Frequently asked questions
The weighted-average buy price is the total amount invested divided by the total quantity held: avg = Σ(price_i × qty_i) / Σ(qty_i). For example, buying 100 shares at ₹250 and 200 shares at ₹275 gives (100×250 + 200×275) / (100+200) = (25,000 + 55,000) / 300 = ₹266.67. It is weighted, not a simple mean of the prices — the 200-share lot pulls the average closer to ₹275 because it carries twice the quantity.
Use the target-average solver: to move a holding of Q shares at average A to a desired average T by buying n shares at price P, n = Q × (A − T) / (T − P). For example, holding 100 shares at ₹250 average, with the current price at ₹200, to reach a ₹220 average you buy n = 100 × (250 − 220) / (220 − 200) = 100 × 30 / 20 = 150 shares. Check: (25,000 + 150×200) / 250 = 55,000 / 250 = ₹220. This only works for averaging down — the target T must sit between the current price P and your existing average A (P < T < A).
Averaging down lowers your break-even price but commits more capital and increases concentration in one position. The decision is best framed by the recovery percentage required: at a ₹250 average with the price at ₹200, the stock must rise +25% just to break even. Buy enough to drop the average to ₹225 and break-even now needs only +12.5% — half the climb — but at the cost of fresh capital and a larger bet on a single stock that is already falling. The calculator shows the new average and the before-vs-after recovery percentage so you can weigh it; it does not tell you whether the company is worth averaging into.
Yes — your true cost basis includes trading charges, not just price × quantity. The true average = (Σ(price_i × qty_i) + total_charges) / Σ(qty_i). In India those charges include brokerage, STT (~0.1% on delivery), GST at 18% on brokerage, stamp duty and DP charges. Simple averagers like Groww ignore these, so they understate your real cost basis — which matters when you compute profit and the capital-gains tax on a sale.
Each lot keeps its own purchase date, so the holding period is decided lot by lot. Shares held more than 12 months qualify as long-term (LTCG); shares held 12 months or less are short-term (STCG) — taxed differently. When you average down, the freshly bought lot starts a new 12-month clock, so part of your holding may be long-term and part short-term at the moment of sale. The calculator can split the position by holding period so you see the tax-aware basis, not just the blended average; the sale tax itself is computed in the Capital Gains Tax Calculator.
Method, assumptions & references
Methodology: weighted average = Σ(price×qty) / Σqty; true cost folds brokerage / STT / GST / stamp / DP into the basis; target-average solver n = Q×(A−T) / (T−P), valid only for averaging down (P < T < A). Golden examples: 100 @ ₹250 + 200 @ ₹275 = ₹266.67 (matches Groww); hold 100 @ ₹250, buy @ ₹200 to reach ₹220 = 150 shares. India charge rates (STT/GST) are static config and rarely change. Charges are estimates — check your broker's contract note. Not financial advice.
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed 16 June 2026. Figures follow the methods and sources set out in our editorial standards.
The weighted-average and target-average calculations are pure, deterministic arithmetic computed from the lots you enter. Trading charges (brokerage, STT, GST, stamp, DP) are estimates — verify the exact figures on your broker's contract note. The averaging-down recovery test quantifies a trade-off; it is not a recommendation to buy. Tax treatment depends on holding period and current law. Not investment or tax advice — consult a SEBI-registered adviser or a qualified CA.
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