Sizing & Risk
Average entry price calculator
“I scaled into this position across several fills — what is my real average price, where is break-even now, and what does the stop cost from here?”
Adding to a position moves the average, and the average is what every other number is measured from. This calculator takes each fill's price and quantity, weights them properly, and reports break-even, the risk from the average to the stop, and the unrealised result at a current price.
Free to use, nothing to sign up for, and nothing you type here is sent anywhere — the arithmetic runs in your browser.
What it computes
total qty = SUM(qty) avg price = SUM(price x qty) / total qty (volume-weighted) break-even = avg price + fee per unit (long; minus, for a short) risk to stop = |avg price - stop| x total qty x point value unrealised = +/-(current - avg price) x total qty x point value
What you type in
| Field | What it means | Example |
|---|---|---|
| Side | Long or short. Flips the sign conventions. | Long |
| Fills | One row per fill: price and quantity. Add as many as needed. | 100 @ 100, 100 @ 92 |
| Stop | Optional. Enables the risk-to-stop figure. | 85 |
| Current price | Optional. Enables unrealised P&L. | 96 |
| Fee per unit | Optional. Shifts break-even against you. | 0 |
| Point value | The instrument's multiplier, as everywhere else. | 1 |
Reading the result
- Average price — volume-weighted across every fill, not a simple mean.
- Break-even — the average shifted by fees, in the direction the position has to move to net flat.
- Risk to stop — measured from the average, not from the first fill.
- Unrealised — what the position is worth at the current price you supply.
Worked example
Long, two fills — 100 @ 100 and 100 @ 92 — stop 85, current price 96.
- Total quantity 200, average price 96.00
- Total cost $19,200
- Break-even 96.00 with no fees
- Risk to stop = (96 - 85) x 200 = $2,200
- Unrealised at 96 = $0 — the position is exactly at its own average
The two sizes are equal here, so the simple and weighted means agree. Change either quantity and they diverge — 500 shares at 92 added to 100 at 100 does not average 96, and that gap is the reason to weight the maths rather than halve two numbers.
What trips people up
- Volume-weighted, not averaged. Unequal fill sizes make the simple mean wrong, sometimes badly.
- Risk to stop is computed from the average price, not the first fill — which is why scaling in against a fixed stop changes the risk being carried.
- The fee shifts break-even the way the position has to move to net flat: up for a long, down for a short.
Questions
- Does it handle scaling out as well as in?
- It averages entries. For a position that has been partially closed, the realised part is a separate calculation — Ledger of Alpha stores each fill on the trade itself and does that arithmetic there.
- Why is my break-even not the same as my average?
- Because a per-unit fee was entered. Break-even is the average plus the round-trip cost, in the direction the trade has to move to net flat.
Related calculators
These are the same calculators built into Ledger of Alpha, where they read your own trade history instead of numbers you re-type. See the full product
Keep the record these numbers come from
A free account logs the trades you size here, so the win rate and averages you type into these calculators come from your own history rather than a guess.