Average Cost Calculator
Track a weighted average entry price across multiple CSE buy lots, then layer in brokerage, break-even exit, and target-sale analysis.
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Position build
Lot-by-lot cost basis
Add each buy lot separately so the weighted average cost reflects how the position was actually built.
Advanced mode
Factor in brokerage drag, exit break-even, and target-sale analysis.
Total shares
1,000
Total invested
LKR 52,000.00
Average cost
LKR 52.00
Unrealised P&L
LKR 6,000.00
Progression
Average cost after each lot
Useful when you want to see whether averaging down or averaging up improved the position basis.
Lot detail
Cost basis breakdown
Each row shows how much capital was committed to that lot and how much weight it carries in the overall position.
| Lot | Shares | Price | Cost | Weight |
|---|---|---|---|---|
| Lot 1 | 1,000 | LKR 52.00 | LKR 52,000.00 | 100.0% |
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Perspective
Cost basis is more useful when it reflects execution reality
A clean weighted average is a good starting point, but active investors usually care about the executable break-even price after brokerage and exit friction, not only the pure purchase average.
Adding lots over time changes your average cost in a path-dependent way. Visualizing how that cost basis evolves by lot helps you understand whether averaging down is genuinely improving your position or simply increasing exposure.
This version keeps the quick weighted-average workflow while adding the more practical decision support most CSE investors actually need.
FAQ
Common questions
What is weighted average cost per share?
It is total invested capital divided by total shares owned. Each lot contributes in proportion to its size, so large lots have a bigger effect on the result than small ones.
Why calculate a break-even sell price?
Because selling friction can mean your true exit threshold is slightly above the average entry cost. Break-even price is the point where net sale proceeds approximately recover your full cost base.
Can I use this for rupee-cost averaging analysis?
Yes. Enter each recurring purchase as a separate lot and the calculator will show the combined weighted average entry price and resulting unrealised P&L.
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