CostAveragingCalculator is a free, independent tool that computes your new average cost basis, total shares/units held, total cost basis, and break-even (or target-gain) price after buying more of a position at a different price. No account, nothing uploaded, no cost.
You enter your original position (quantity and price) and a new buy (quantity and price) — or, for more than two buys, switch to the multi-lot table and add a row per purchase. The tool applies the standard weighted-average formula: new average cost = Σ(quantity × price) / Σ(quantity) across every lot, then shows the price you'd need to break even or hit a target gain percentage you choose. If you enter a current market price, it also shows your unrealized gain or loss. Full mechanics, including a worked example, are on the How We Calculate page.
Investors and traders — in stocks, ETFs, crypto, or options — who are considering buying more of a position at a new price ("averaging down") or who buy on a recurring schedule (dollar cost averaging) and want to quickly see their blended average cost without doing the weighted-average math by hand.
"Averaging down calculator" and "average cost calculator" are searched across stocks, crypto, and options communities worldwide, but no single free, independent tool dominates the space the way niche calculators sometimes do — most existing options are buried inside broker sites or scattered across finance blog posts. This tool exists as a fast, ad-light, single-purpose alternative that works the same way for any asset type — see the dedicated pages on stocks, crypto, and options for how the risk side of that differs by asset class even though the math doesn't.
All calculations happen in your browser — nothing is uploaded to, or stored on, any server. See the privacy policy for full detail.
Questions or corrections: support@costaveragingcalculator.com