How to use the average down calculator
Enter your current position (average price and quantity) and the price and quantity of each new buy. The new average price updates instantly. Add as many buys as you need with + Add buy; the table shows how the average changes after each one.
Add the current price to see unrealized profit or loss, your return, and how far the price must rise to break even. Want to know how many shares it takes to reach a specific average? Switch to Target avg.
- For crypto or fractional shares choose Crypto; the required quantity is calculated to 8 decimal places. For stocks it is rounded up to a whole share.
- Save positions by name to reload them later. They are stored only in this browser.
- Share link creates a URL containing your inputs so you can open the same calculation on another device.
Average price formula with an example
Average price = (held average × held quantity + price₁ × qty₁ + price₂ × qty₂ + …) ÷ total quantity
- You hold 10 shares at $150 and buy 10 more at $120: (1,500 + 1,200) ÷ 20 = $135, a 10% lower average.
- At a current price of $125 your position is worth $2,500 against a $2,700 cost: a loss of $200, or about −7.4%.
Shares needed for a target average
If you hold q shares at average a and buy x more at price p, the new average is (q·a + x·p) ÷ (q + x). Solving for a target average t gives:
x = q × (a − t) ÷ (t − p)
Example: 10 shares at $150, buying at $120, target $135 → 10 × 15 ÷ 15 = 10 shares. The closer the target is to the buy price, the faster the required quantity grows, so check the amount needed before you commit. The target must lie between the buy price and your current average; averaging up uses the same formula.
Break-even price after fees
To truly break even you must recover buy-side fees and pay sell-side fees and taxes. The calculator uses:
Break-even = total cost including buy fees ÷ (quantity × (1 − sell fee rate))
Example: 20 shares bought for $2,700 with a 0.1% buy fee costs $2,702.70. With 0.1% in sell-side costs the break-even price is 2,702.70 ÷ (20 × 0.999) ≈ $135.27. These rates are illustrations only; use the rates from your own broker or exchange.
Before you average down
Lowering your average helps you break even sooner if the price recovers, but it also concentrates more money in a falling position. Consider whether your original reason for buying still holds, how large the position becomes relative to your portfolio, and whether the buy is part of a pre-planned scaling strategy rather than a reaction to a loss.
FAQ
Does the average price include fees?
The calculator shows both: the average without fees and the average including buy fees. Brokers differ in whether their displayed average cost includes commissions, so compare with your account.
Does selling part of my position change the average?
With the moving-average method, selling some shares leaves the average price of the remaining shares unchanged; only the quantity drops. Tax lot methods such as FIFO used for tax reporting can differ.
Why does the target average say it cannot be reached?
The target must be between the buy price and your current average. You can never bring the average below the price you are buying at, no matter how many shares you add.
Can I use it for crypto or fractional shares?
Yes. Quantities accept decimals such as 0.015, and choosing Crypto calculates the required quantity to 8 decimal places.
Is my data sent anywhere?
No. Everything is calculated in your browser and saved positions stay on this device. Inputs are only placed in a URL when you press Share link.