The smallest amount a bid can rise by. If the current bid is ₹500 and the increment is ₹25, the next bid is ₹525 — not ₹505.
It exists so an auction cannot be dragged out a rupee at a time.
Where the figure comes from
Unless the seller sets their own, it is 5% of the starting price, with a floor of ₹10. An item starting at ₹500 gets ₹25; an item starting at ₹100 gets ₹10, because 5% would be ₹5.
The thing most people get wrong
It is worked out from the start price, and it does not rise as the bidding does.
So an item that started at ₹500 has a ₹25 increment at ₹500 and still has a ₹25 increment at ₹5,000. It does not scale up with the price.
That is worth knowing in both directions. As a bidder, a hot item late on moves in steps that are small relative to the price, so the ending can take a while. As a seller, an item you expect to go far past its start will crawl the last stretch in small steps — which is one reason to think about the start price rather than only the reserve. How to price for auction
Sellers can set their own
Any seller can override the default on a listing. Bigger steps end an auction faster and can cut off a bidder who would have gone one more step; smaller steps keep more people in and take longer.
Neither is right in general. What is reliably wrong is an increment large relative to the item — a ₹200 step on a ₹300 item means effectively one bid. Can I set my own increments?
What it is not
Not the reserve. The increment is how fast bidding climbs; the reserve is the price below which you will not sell. What is a reserve price?
Not a fee. Nothing about the increment costs anybody anything.
Not the thing that decides who wins. That is the highest bid when the clock stops — and a bid in the last ten seconds pushes the clock back out. The last ten seconds
For bidders, practically
You do not have to calculate it. The app offers you the next valid bid and you tap it.
What is worth deciding before the item comes up is your ceiling — the number above which you stop. Increments are small enough, late on, that "one more step" is an easy thing to keep saying. How to bid without overpaying
More: can I set my own increments, auction words, explained, why is the price jumping.