Free Stock Average Calculator (+ Guide)

What is a stock average calculator?

A stock average calculator works out the average price you paid for a stock or fund you bought in several lots.

This one adds what it's worth now, and the shares a next buy takes to move the average to a target.

How it works

The calculator works it out on your device, and your numbers stay there.

Averaging down and up

Averaging down means buying more below your average, so the average falls. Averaging up is buying above it.

The shares to reach a target come from setting the new average equal to it: (total paid + n × next price) ÷ (shares + n) = target.

The target has to sit between the next price and your average now, or no number of shares gets you there.

A worked example

Here's the example the calculator loads: 10 shares at $50 and 10 at $30, now trading at $35.

Your average is $40: $800 for 20 shares. At $35 you're down $100, or 12.5%.

To bring the average to $35 with a buy at $30, you'd buy 20 more shares for $600.

Mistakes to avoid

These are the slips that come up most.

• Averaging down only because the price fell, with no new reason to own more
• Leaving fees out of what you paid
• Mixing buys from different accounts with different tax rules
• Treating a lower average as a smaller loss, when the money at risk grew

Who is the stock average calculator for?

It's for investors who buy the same stock or fund more than once, and these tools help around it.

• CAGR calculator – for a holding's yearly growth
• Percentage calculator – for any change in percent
• Compound interest calculator – for growth at any rate
• ROI calculator – for the return on what you paid

Know your average before the next buy, and decide on a reason, not a price.