Core concept
Average price is a weighted average of purchase amounts
When you buy at different prices, you do not simply add the prices and divide. Each price is multiplied by its quantity, and the total cost is divided by the total quantity.
Given a target average price, the calculator can work backward from your current holding and additional purchase price to find the required quantity and investment.
Calculate after purchase
(Current average price × Current quantity + Purchase price × Purchase quantity) ÷ Total quantity
Calculate a target average
The calculator first checks whether the target is reachable, then calculates the additional quantity needed.
Example
Adding 5 shares at KRW 60,000 to 10 shares at KRW 70,000
Total invested amount
KRW 1,000,000
Total quantity
15 shares
New average price
KRW 66,667
Reachability
The average price moves between the two purchase prices
After an additional purchase, the new average stays between the current average price and the additional purchase price. A target outside that range cannot be reached by repeatedly buying at the same price. In that case, the calculator explains why instead of treating the scenario as an input error.
Before using the result
- Fees, taxes, exchange rates, and differences in actual execution prices are not included.
- Calculations preserve fractional quantities and round only for display. Fractional share availability depends on the market and brokerage.
- Results are based on your inputs and do not recommend buying or selling any security.
Frequently asked questions
How should I enter numbers?
4,673 and 4673 are treated as the same value. Use only digits, decimal points, and correctly placed thousands separators. Do not enter unit text such as KRW or shares.
What happens if the additional quantity is zero?
If you already hold shares, the average price and total invested amount remain unchanged.
Can I calculate before I own any shares?
Enter 0 for the current average price and quantity, then enter the new purchase price and quantity to see the values after your first purchase.
Can the result differ from my brokerage account?
Yes. Brokerage fee policies, whole-KRW handling, and actual execution prices can produce different values.
What does an unreachable target average mean?
The target is outside the range between the two prices or cannot be reached exactly with a finite additional quantity. Changing the target or purchase price may change the result.
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