Stock average calculator. Two modes, one page.

The math

Forward mode:
  newAvg = (X · A + Y · P) / (X + Y)

  X = current quantity
  A = current average cost
  Y = additional shares
  P = price you'll buy at

Target mode (solve for Y):
  Y = X · (A − Z) / (Z − P)

  Z = target average

Feasibility:
  - Averaging down (Z < A) requires P < Z
  - Averaging up   (Z > A) requires P > Z
  - At any other price the target can't be reached

When averaging down works

Averaging down is a logical move on a quality business where the price drop is sentiment-driven (sector rotation, headline panic, broad-market drawdown) and fundamentals are intact. Lowering your cost basis on a stock that'll recover shortens the path to break-even.

It's a destructive move on a structurally-weak stock — earnings deteriorating, promoter pledge rising, governance flags showing. The Indian-retail forum phrase for this is “catching a falling knife.” Cross-check the convergence verdict and Piotroski score on the stock's page before adding.

Tools to sanity-check before averaging down: 3-lens convergence · Piotroski quality · 30-day Kronos forecast

Tax + brokerage considerations

Indian capital-gains tax is computed lot-by-lot using the FIFO method by default — so even if your averagecost is ₹450, the tax authorities treat each lot you sell as coming from your earliest purchase first. A lower average isn't the same as a lower future tax liability.

For tax math on equity sales, see ITR helper or the tax estimator (post sign-in, FY26).