Every Dhanteras, the queue outside the jeweller's shop starts before the shutters go up. Millions of Indian families buy a little gold that day — to wear, to keep, or because it is simply what the family has always done. Watch two people in that queue and you can see the whole idea of this article without any theory at all. The first buyer asks for ten grams every year, and pays whatever the rate is that morning. The second hands over the same fixed amount every year — say ₹20,000 — and takes home whatever quantity that buys on the day.
They spend the same kind of money for the same number of years. They do not end up with the same amount of gold.
Why the fixed-amount buyer ends up with more metal
The buyer who fixes the quantity has no choice about price. In an expensive year he still buys ten grams, at the expensive price. The buyer who fixes the amount does something different without thinking about it: in a cheap year ₹20,000 buys a lot of gold, and in an expensive year the same ₹20,000 buys very little. She automatically buys more when it is cheap and less when it is dear.
Here is the arithmetic on made-up numbers, chosen only because they are round enough to follow. These are not real gold prices and not a forecast — they are there to make the mechanism visible. Say the price per ten grams is ₹10,000 in the first year, ₹20,000 in the second and ₹40,000 in the third.
- Fixed quantity: ten grams each year, three years, thirty grams in total, at a cost of ₹70,000. That works out to about ₹23,300 per ten grams.
- Fixed amount: ₹20,000 each year buys twenty grams, then ten grams, then five grams — thirty-five grams in total, at a cost of ₹60,000. That works out to about ₹17,100 per ten grams.
More metal, less money spent, and nobody predicted anything. The second buyer never had a view on where gold was going. The rule she followed did the work.
The same mechanism has a name in the market
This is rupee-cost averaging: when you put in a fixed sum on a fixed schedule, the price you end up paying is an average across many dates rather than whatever the price happened to be on the one date you chose.
A Systematic Investment Plan (SIP) is the version of this for mutual funds — a fixed amount invested on a set date each month, buying however many units that amount covers at that day's price. Fund units move in price just as gold does, so the same arithmetic applies.
Be clear about what this claims. Rupee-cost averaging is a statement about your average purchase price, not about your profit. It does not stop a fund from falling, and it is not on its own a reason to prefer one route into the market over another. Whether a large amount is better deployed in one go or spread over months is a genuinely open argument, and two companion articles on this site put each side of it.
What it actually solves is a human problem
The stronger case has less to do with arithmetic than with what people do when left to decide each month. It takes the monthly decision away from you. Invest by hand and you must sit down each month and press the button — the moment at which the headlines get a vote. The market looks expensive, so it can wait. It looks frightening, so it can definitely wait. It has been climbing, so perhaps put in extra. A standing instruction does not read the news.
That is the honest version of the story. Not magic, and not a return you can count on. What it does is remove your worst moments from the process — the month you were too nervous and the month you were too excited — and let a rule do something you were unlikely to do consistently on your own.
Whether that route suits you at all depends on your goals, your horizon and what else you own. Those are decisions to work through for yourself, or with someone qualified and registered to advise you.
This article is general information for education only. It is not investment advice and does not take account of your circumstances. Investments in securities are subject to market risks; please read all related documents carefully before investing.
