Estimates only — not financial, tax, or professional advice.
100% private — every number you enter is calculated in your browser and never sent to our servers.
What it calculates: Total Coins Bought, Current Value, Total Invested, Average Cost per Coin.
Updated 5 June 2026 · Transparent assumptions
The average cost sits below the average price, always
Investing a fixed amount each period buys more units when the price is down and fewer when it is up, so the quantity is weighted toward the cheaper periods. The resulting average cost per unit is the harmonic mean of the prices, which is always at or below their arithmetic mean.
The two coincide only if the price never moves. Every fluctuation, up or down, widens the gap — which is the entire mathematical case for averaging in, and it holds regardless of which direction the price ultimately went.
A real price path is not a ramp, and the difference is not small
The calculator interpolates evenly from the start price to the end price across the periods. That is a clean way to test a scenario, but no asset has ever moved that way, least of all this one.
The direction of the error is knowable though: because volatility always helps an averaging plan, a real path that wandered between the same two endpoints would have produced a lower average cost than this model shows. Treat the result as a conservative case.
A lump sum usually wins on the numbers, and that is not the point
In a market that rises more often than it falls, investing everything at the start beats spreading it out most of the time, simply because the money is exposed for longer. Studies of equity markets find this in roughly two thirds of periods.
The case for averaging in is that it is a plan someone can actually follow. A schedule removes the decision of when to buy, which is the decision most likely to be made badly during a sharp fall — and an imperfect plan followed beats an optimal one abandoned.
Every purchase made, one fee rate, and no tax
The model assumes every scheduled purchase happens on time at one fee rate, and values the whole holding at the end price. Missed contributions, a changed fee tier, or a partial sale part way through all break that.
It is also pre-tax, and a position built from many purchases has many cost basis lots. Which of them a later sale is matched against depends on the rules where you are taxed, and it can change the gain substantially.
Sources & References
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
Crypto ProfitProfit and return on a round trip, with a separate fee rate on the buy and the sell side.
Bitcoin ReturnWhat an amount invested at one price is worth at another, with the entry fee taken off before the coins are bought.
Regular InvestmentProject how regular monthly contributions grow over time — SIP-style investing, dollar-cost averaging, inflation-adjusted value, and long-term goals.
Step-Up SIPWhat a monthly investment grows to when you raise it every year, with the real value after inflation.
Returns are assumptions, not guarantees. Actual results may vary because of market performance, taxes, fees, inflation, and timing. This is an educational projection, not investment advice.
Published the calculator with its formula, worked example, assumptions, limitations and a bespoke guide, and added an automated formula test suite covering it.
Tested the units accumulated across a price path against an independently run loop, and the blended average cost that results.
Tested that the average cost never exceeds the average price, with equality only when the price never moves.
Add this calculator to your site
Responsive embed — and private: nothing your visitors type leaves their browser.