Average Purchase Price Calculator
Find the weighted average price across several purchases of the same holding, before and after fees, and see where that leaves you today.
Formula and method
Average excluding fees = Σ(quantity × price) ÷ Σ(quantity).
Average including fees = (Σ(quantity × price) + Σ fees) ÷ Σ(quantity). This is your break-even price per unit.
Unrealised gain or loss compares the current value of the total quantity with everything you paid, fees included.
Worked example
Buy 10 units at €100, then 20 units at €130.
Total paid = €1,000 + €2,600 = €3,600 for 30 units, so the average is €3,600 ÷ 30 = €120.
Note this is below the €115 simple mean of €100 and €130 only when the cheaper purchase is larger - here the larger purchase was the more expensive one, so the weighted average sits above it.
FAQ
Frequently asked questions
How do you work out an average purchase price?
Total amount paid divided by total units bought. It's a weighted average, so a large purchase moves the number far more than a small one.
Should I count dealing fees?
Both figures are shown here. The average excluding fees is what the market charged you; the average including fees is your real break-even price.
What is dollar-cost averaging?
Investing a fixed amount on a schedule. It buys more units when prices dip and fewer when they spike, which usually pulls the average below the simple mean of the prices paid.
Does this handle sales too?
No, purchases only. It shows the cost basis of what you hold, not any gain or loss you've already realised by selling.
Can I use this as my tax cost basis?
Not automatically. Tax rules differ - some places require average cost, others FIFO or share-pooling. Check with a tax adviser before you file anything.
More free tools