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Updated year criteria 2026
Average Cost of Shares Calculator
The Average Cost of Shares Calculator estimates a cost estimation estimate for your scenario from the quantities, rates, period, units and other assumptions requested on the page. Replace the example values with your own average shares figures and recalculate after changing an assumption. Use it to compare scenarios, then verify any current rate or fee before acting.
Calculate the average cost per share of multiple purchases at different prices and compare profit/loss at current market prices.
Calculation results
Average cost.
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Total shares
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Total cost
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Market value
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Profit/Loss
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Profit/loss %
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How to calculate average cost per share
When buying stocks multiple times at different prices, knowing the true average cost helps to estimate profit/loss correctly and make informed decisions about buying or selling more.
Weighted Average Cost
Average cost = Σ(purchase price × number of shares) ÷ total number of shares Profit/loss = (market price - average cost) × total number of shares
If the market price is 55 baht: Profit = (55 − 43.33) × 300 = 3,501 baht
Frequently asked questions
How is the average cost per share calculated?
Weighted Average Cost is calculated by taking the sum of (purchase price × number of shares) each time divided by the total number of shares. For example, buying 100 shares at 50 baht and 200 shares at 40 baht. Average cost = (5,000+8,000)/(100+200) = 43.33 baht/share.
Why calculate average cost of shares?
Knowing the true average cost helps to estimate profit/loss correctly, make appropriate decisions on selling shares, and is used for capital gains tax calculations, which are essential in managing portfolios.
What is Dollar Cost Averaging (DCA)?
DCA is a strategy of buying stocks or funds at a fixed amount every instalment, regardless of price. When high prices get less stock, when low prices get more stock, making the average cost lower than buying one time at high prices.
Should I buy more shares when the price drops?
Averaging down can help reduce average costs, but there is a risk that if the company's fundamentals are worse, it should be considered whether the price is down because of the market as a whole or because of company-specific factors, rather than buying more just to reduce average costs.
Check before using results
Summary before deciding
This calculation result is suitable for preliminary planning. Actual figures should be checked from documents or official sources before making important decisions.
The calculation is based on the information you enter on this page.
Special cases may require additional information.
It is recommended to record or compare the results with the related tools below.
Disclaimer: The results of the calculations are estimates only, excluding commissions and trading fees, and are not financial advice.
English calculator guide
How to use the Average Cost of Shares Calculator
Use this page to test a specific average shares scenario. Enter your own values in the calculator above, review the units beside each field, and recalculate after changing an assumption. The result updates the average cost of shares estimate instead of relying on a generic example.
Build a baseline average shares case with figures that match your situation.
Run a second average shares case after changing the rate, period, quantity or other key assumption.
Record the difference between the two average shares results and the input responsible for it.
Inputs for the average shares estimate
For this average shares calculation, check the quantities, rates, period, units and other assumptions requested on the page. The result is designed to show a cost estimation estimate for your scenario, not a guaranteed provider price or official decision.
How the average shares result is calculated
The calculator combines the entered quantities, rates and fixed costs to produce the displayed estimate. Reusing the same average shares inputs will produce the same estimate, which makes the page suitable for controlled scenario comparisons.
Checks for a average shares decision
Confirm any current rate, threshold or provider rule that could change the final amount. For average shares, Use the result as a planning estimate and confirm any rate, rule or threshold that may have changed before acting. Recheck the entered values and units if the result looks unexpected.
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Review formula structure, test cases, data sources, effective dates, and risk language accordingly.How to check our · There is no claim that an outside professional reviewed it. Unless the page directly states the name and qualifications. This content is therefore not individual advice.
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