How to Calculate Your Average Buy Price in Crypto
If you have bought the same coin more than once, you need a single number that represents what you paid on average. That number — your average buy price — tells you whether your position is in profit, what price you need to exit even, and how much each new purchase changes your position.
The catch is that a simple average of your purchase prices is usually wrong. You need a weighted average.
Why a simple average fails
Imagine two Bitcoin purchases: $100 at $20,000 and $10,000 at $60,000. A simple average of the two prices is $40,000. But almost all of your money went in at $60,000, so your real average is much closer to that. The weighted average accounts for how much you bought at each price.
Run your own numbers with the free calculator: Crypto Profit Calculator
Open calculator →The weighted average formula
Average buy price = Total amount spent ÷ Total coins received
Include fees in the amount spent. That way, your average already reflects the true cost of each coin.
Using the example above:
- Purchase 1: $100 buys 0.005 BTC
- Purchase 2: $10,000 buys 0.16667 BTC
- Total: $10,100 for 0.17167 BTC
- Average = $58,835
Worked example with fees
| Date | Price | Spent | Fee | Coins received |
|---|---|---|---|---|
| Jan | $3,000 | $500 | $2.50 | 0.16583 ETH |
| Mar | $2,400 | $500 | $2.50 | 0.20729 ETH |
| Jun | $3,600 | $1,000 | $5.00 | 0.27639 ETH |
| Total | $2,000 | 0.64951 ETH |
Average buy price = $2,000 ÷ 0.64951 = $3,079.24 per ETH.
Notice the average is above the March price and below the June price, pulled toward June because that was the largest purchase.
How a new purchase changes your average
Before buying more, you can calculate your new average in advance:
New average = (Current total spent + New amount) ÷ (Current coins + New coins)
Using the ETH position above, buying another $1,000 at $2,500 (0.4 ETH, ignoring fees):
- New total spent: $3,000
- New coins: 1.04951 ETH
- New average: $2,858.47
This is the math behind "averaging down". It lowers your break-even, but it also increases how much money you have riding on the same asset. Read more in our guide to averaging down.
What about coins you have sold?
When you sell part of a position, the average cost of the coins you still hold does not change under the weighted-average approach. If your average is $3,079 and you sell half your ETH, the remaining half still has an average cost of $3,079. Your realized gain on the sold half is measured against that same average.
Average price vs tax cost basis
Your personal average price is a great tool for decision-making, but tax authorities may require a different method:
- United States: gains are generally calculated using specific identification or FIFO (first in, first out), tracked per wallet or account. Your tax gain on a sale can differ significantly from your average-price gain.
- United Kingdom: HMRC uses share pooling (Section 104), which is effectively a weighted average — but with same-day and 30-day matching rules applied first.
- Canada: the CRA uses the adjusted cost base (ACB), which is also a weighted average across identical properties.
Our guide to crypto cost basis methods explains each in detail.
Tips for keeping track
- Export your trade history from each exchange at least once a year.
- Keep fees and network costs, since they increase your cost basis.
- If you hold the same coin on several platforms, combine them for your personal average, but remember US tax rules now track basis per account.
- Record transfers between your own wallets so they are not mistaken for buys or sells.
Check your position
Once you know your average buy price, enter it in the crypto profit calculator with the current price to see your unrealized profit, ROI and break-even after fees.
CryptoMathly provides educational estimates only and is not financial, investment or tax advice. Crypto assets are volatile and you can lose money. Always verify figures with a qualified professional.