Scaling In and Out Calculator
Find your average entry across tranches, or realised profit when scaling out.
Please note: Trading carries substantial risk of loss. These calculators are planning tools, not trading advice, and no position sizing method prevents losses.
What the Scaling In and Out Calculator does
Building or closing a position in tranches means the effective price is a size-weighted average rather than a simple one. That distinction matters: a large tranche at a poor price dominates the average, while a small one barely registers.
Formula
Average price = Σ (Price × Size) ÷ Σ SizeRealised profit = (Average exit − Average entry) × Units closed, reversed for a shortRemaining position = Total − Units closed
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Calculate | one of 2 options | Yes | — |
| Direction | one of 2 options | Yes | — |
| Prices | text | Yes | Entry prices when scaling in, exit prices when scaling out. |
| Sizes | text | Yes | Units at each price, in the same order. |
| Average entry price | selected currency | In some modes | Accepts more than 0. Shown Calculate is Scaling out — realised profit. |
| Total position size | units | Optional | Accepts 0 or more. Shown Calculate is Scaling out — realised profit. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Calculate and Direction.
- Enter Prices and Sizes.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
Buying 1,000 units at 100, another 1,000 at 95 and another 1,000 at 90.
- Mode
- Scaling in
- Prices
- 100, 95, 90
- Sizes
- 1000, 1000, 1000
Total cost 285,000 for 3,000 units, so the average entry is 95 — an improvement of 5 on the first fill.
Frequently asked questions
Is averaging down a good idea?
It lowers your average price but increases exposure to a position that is already moving against you. It works when the thesis is sound and the size was planned in advance; it is ruinous when used to avoid admitting a mistake.
Why is the weighted average different from the simple average?
Because tranches differ in size. Three equal tranches give the same answer both ways, but buying 100 units at 50 and 900 at 100 averages 95, not 75.
Method and sources
Method. Size-weighted average entry or exit price across the tranches entered, with the resulting position and its average cost.
Assumptions
- Each tranche fills at the price entered.
Limitations
- A falling average entry price is arithmetic, not improvement. Averaging down reduces the average cost while increasing the amount at risk in a position already moving against you.
- The calculator prices the plan you describe; it takes no view on whether adding to the position is sound.