Stock Average Calculator
Combine multiple stock purchases into a charge-aware weighted average, see today’s unrealised result and calculate the new exposure required to reach a target average.
Map purchase lots, current P&L and the cost of moving your weighted average.
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Averaging down increases the capital exposed to the same company. Recheck the business thesis, concentration, liquidity and your maximum acceptable loss before adding merely because the price fell.
For dematerialised securities in India, disposals are generally matched using FIFO. Keep contract notes, charge records and depository statements; use the calculator for position tracking, not tax filing.
The live P&L excludes sell-side brokerage, taxes, DP charges and corporate-action adjustments unless you have already reflected them in the entered lots.
What a weighted average price is
If you bought the same stock more than once at different prices, your effective cost is not the simple average of those prices. It is the weighted average — weighted by how many shares you bought at each price.
This number matters because every profit or loss you calculate, and every tax computation you eventually file, works from it.
The formula
Weighted average price = Total amount invested ÷ Total shares held
Where total amount invested is the sum of (quantity × price) for every purchase.
A worked example
Three purchases of the same stock:
| Purchase | Quantity | Price | Amount |
|---|---|---|---|
| 1 | 50 | ₹500 | ₹25,000 |
| 2 | 100 | ₹400 | ₹40,000 |
| 3 | 50 | ₹350 | ₹17,500 |
| Total | 200 | ₹82,500 |
Weighted average = ₹82,500 ÷ 200 = ₹412.50
Note how this differs from the simple average of the three prices, which would be ₹416.67. The second purchase carries twice the weight of the others because you bought twice as many shares. The simple average is wrong, and using it would misstate your position.
On averaging down
Buying more of a falling stock lowers your average price. That is arithmetic, and the calculator will confirm it.
What the lower average does not do is make the investment better. It reduces the price at which you break even, and it increases the amount of money you have committed to a position that has so far moved against you. If the original reason for holding no longer applies, a lower average price simply means a larger stake in a worse idea.
This is a widely misunderstood point, and it is worth being clear about: the calculator tells you what your average is. It does not tell you whether buying more is sensible. That judgement depends on the company, your reasoning and your circumstances, and it is not something any calculator can answer.
What this calculator excludes
- Brokerage on each transaction
- Securities Transaction Tax (STT)
- Exchange, SEBI and stamp charges
- GST on brokerage
Together these are small on a single trade but meaningful across many. Your broker’s contract note shows the true landed cost per share, and that is the figure to use for tax purposes.
Corporate actions also change your average. A bonus issue or stock split increases your share count without new money, which reduces your average price mechanically.
Related: What Are Corporate Actions? · Stock Return Calculator
Frequently asked questions
How is the weighted average stock price calculated?
Each purchase price is multiplied by its quantity. The calculator adds those purchase amounts and any buy charges you enter, then divides the total by the total shares. It does not take a simple average of the displayed prices.
Should I include brokerage and other charges?
Include known buy-side charges when you want a closer portfolio break-even estimate. Keep the amount tied to each contract note. The current profit or loss still excludes future sell-side brokerage, taxes, DP charges and other exit costs.
How does the target-average solver work?
It solves the additional quantity needed at your planned buy price so the combined position reaches the selected target average. The target must sit between the current weighted average and the planned buy price. The displayed action quantity is rounded up to the next whole share.
Why does the calculator say the target is not reachable?
Buying at one price can only pull the weighted average towards that price; it cannot move the average beyond it. A target outside the interval between your current average and planned buy price is therefore not reachable with that single planned price.
Does my broker show the same average price?
It may differ because brokers can present charges, corporate actions, transfers and partial disposals differently. Reconcile the calculator with contract notes, the broker ledger and your depository statement rather than treating one screen value as the legal record.
Is the portfolio average also the tax cost in India?
Not necessarily. For dematerialised securities, Indian capital-gains identification generally applies first-in-first-out to disposals. A pooled position average is useful for portfolio tracking, but tax reporting needs the remaining acquisition lots, dates, costs and applicable corporate-action treatment.
What happens after a bonus issue or stock split?
The share count and comparable per-share cost change even though the mechanical total cost remains continuous. Use the dedicated Bonus Share or Stock Split Calculator, then update the lot record only after checking the company, exchange and depository documents.
Is a lower average price always better?
No. It lowers the portfolio break-even price but also increases capital exposed to the same company. A falling price can reflect a damaged business thesis, and repeated averaging can increase concentration and total loss.