BTC Average Cost Calculator

Bought Bitcoin (BTC) at several different prices? Log each buy to see total invested, coins held, average cost and floating P&L at the current price.

How to use

Click "Add buy" and enter the amount invested and price for each purchase. Optionally enter the current price to see floating P&L.

Results show total invested, coins held, average cost, current value, floating P&L and return.

Formulas

Coins heldΣ (investment ÷ buy price) per buy
Average costTotal invested ÷ coins held
Floating P&LCoins held × current price − total invested

Example

Buy 1,000 USDT each at 3,000 / 2,500 / 2,000: total 3,000 USDT, coins ≈ 1.2167, average cost ≈ 2,465 — below the simple average of 2,500, showing the effect of buying more at lower prices.

Notes

Fees are excluded. A lower average cost does not shrink losses — floating P&L depends on current price vs total invested.

FAQ

How is average cost calculated?

Average cost = total invested ÷ coins held, where coins = Σ (investment ÷ buy price). It is weighted by money, not a simple price average.

Why does buying more at lower prices lower the average?

The same dollar amount buys more coins at a low price, tilting your cost basis down. In the example the simple average is 2,500 but the weighted cost is ≈ 2,465.