How many metres of series lights do you need? Balcony, window, door, 2BHK, terrace

Short answer: measure the edge you want lit in metres, add 15% for corners and slack, and round up to the next length sold. A standard balcony railing takes 8 to 10 metres. One window frame takes 5 metres. A main door frame takes 6 to 7 metres. A modestly decorated 2BHK takes 30 to 40 metres in total, and an open terrace starts at 50 metres. That is how many metres of series lights you need for almost every home; the rest of this guide gives you the number for each space and explains where the length actually goes.

Measure the edge, not the room

The most common mistake with series lights for home decoration is estimating by room size. Square feet is the wrong unit. Lights follow edges: railings, window frames, door frames, the line where a wall meets the ceiling, the top of a parapet. A 10 by 12 foot bedroom and a 14 by 16 foot living room have very different floors and almost the same perimeter at the ceiling.

Walk the actual path you want lit with a tape measure or the measuring app on your phone, and write the number down in metres. That figure, plus 15%, is the length you buy. If the path turns corners, count them; if it climbs a pillar or wraps a tree, read the wrapping section below before you trust the tape.

How many metres of series lights per space

These are the numbers we give people on WhatsApp when they send a photo. They assume a loose wrap on railings and a single straight run around frames, which is how most series lights for decoration end up being fixed.

The rest of the guide takes these one at a time, because the numbers hide assumptions that matter.

Balcony: 8 to 10 metres on the railing, 15 with the sides

A typical apartment balcony is 1.2 to 1.5 metres deep and 3 to 4 metres long. Laid straight along the railing that is only 4 to 6 metres of edge, which is why people buy 5 metres and run out. Nobody lays a series light straight along a railing; it gets wrapped once around the top rail per gap, and the wrap is what eats the length. Wrapped, the same railing takes 8 to 10 metres.

Add both side walls, from the slab down to the rail, and you are at 12 to 15 metres, which is why a single 15 metre string is the usual buy and the default in every Diwali balcony layout we suggest. The ceiling line is a further 4 to 6 metres and is best done as a second, separate string plugged in on its own.

One thing the metres do not tell you: whether the railing gets rain. An open railing needs an IP44 rating at minimum, and anything past the slab edge needs IP65. Our 5, 10 and 20 metre rice lights are IP20, indoor only, so on a balcony they belong on a fully covered or glazed one. The 15 metre pixel string is IP44 and is the one for an open railing; the difference between a rice light and a pixel light is brightness and rating, not metres.

Window: 5 metres for a standard frame

A standard window of about 1.2 by 1.5 metres has a perimeter of 5.4 metres, but the string does not need to close the loop: it starts at the bottom corner nearest the socket, goes up, across, down and along, and the last stretch is the lead to the plug. 5 metres does it. A large living room window or a sliding balcony door is 8 to 10 metres.

If you want a curtain of light across the glass rather than an outline, you are no longer buying by perimeter. A curtain effect is vertical drops every 15 to 20 centimetres, each drop the height of the window, so a 1.5 metre wide, 1.5 metre tall window takes 12 to 15 metres of string and a lot of patience. Purpose-made curtain lights do this better than a series light, and we say so.

Main door and door frame: 6 to 7 metres

The outside of a main door frame is about 1 metre wide and 2.1 metres tall. Up one side, across the top, down the other is 5.2 metres, plus the lead to the nearest socket, which is usually inside the door and means routing the wire over the top of the frame or through the gap at the hinge side. Budget 6 to 7 metres, buy a 10 metre string, and tuck the spare behind the frame or double it along the top where it reads as a thicker band of light.

If the door has a toran or a marigold garland, the string goes behind it, not over it; marigold on a warm white string looks like it is lit from inside.

One room outlined at the ceiling: 18 to 22 metres

Outlining a room where the walls meet the ceiling is the most metres for the least effect, and we tell people that. A 10 by 12 foot room is 13.4 metres around; a 12 by 14 foot room is 15.8 metres. Add the drop to a socket, which in most Indian rooms is at switchboard height, and add the 15%, and you are at 18 to 22 metres. A single 20 metre string does it. Two 10 metre strings do it with a visible join and two plugs.

Before you buy 20 metres for a bedroom, consider a headboard wall or a single window instead. The room reads as decorated for a third of the metres.

A whole 2BHK or 3BHK: 30 to 60 metres, in pieces

How many metres of series lights for Diwali decoration at home? For a 2BHK doing what visitors actually see, the balcony, the main door and one or two windows, it is 30 to 40 metres. A 3BHK done properly, with a second balcony and more windows, is 50 to 60 metres. In both cases that total is several strings on several sockets, not one run.

A realistic 2BHK list looks like this: one 15 metre IP44 string for the balcony, one 10 metre string for the main door, one or two 10 metre strings for windows. That is 35 to 45 metres bought as four strings, each with its own plug and its own failure. If the balcony string dies, the door is still lit, and a 10 metre replacement is ₹299 rather than a whole new set.

Terrace, parapet, compound wall and gate: measure, then divide

The perimeter of an open terrace starts at 50 metres on a mid-size flat and runs to 60 to 80 metres on an independent house. A compound wall and gate run is anything from 30 to 80 metres. These are the spaces where people go looking for a 100 metre string, and the space where it is the worst idea, for reasons in the next section.

Measure the parapet, add 15%, then divide by 20 and buy that many 20 metre strings, or by 15 and buy IP44 or IP65 strings as the exposure demands. Every string fixed to an open parapet sees direct rain and needs IP65, and the controllers and plugs still need to sit under cover. For a gate, the honest answer is often not more metres at all: one 20 or 50 watt focus light aimed at the gate or the wall behind it does more from the road than 30 metres of string, and which of the three wattages depends on the height of the wall.

Trees, pillars and anything you wrap tightly

Wrapping is where measurements go wrong by the largest factor. A straight run uses the tape measurement once. A loose wrap on a railing, one turn per gap between bars, uses one and a half to two times the run. A tight wrap on a pillar or a tree trunk, turns touching or nearly touching, uses three to four times the height.

So a 3 metre porch pillar wrapped tight is 9 to 12 metres of string. A 2 metre shrub is 10 metres for a light dressing and 20 for something that reads from the road. A shop front one shutter wide, about 3 metres, outlined and with a zigzag across the signboard, is 12 to 15 metres.

Do you really need 100 metres?

The searches say a lot of people look for rice lights 100 meters, and marketplaces are full of 50 and 100 metre listings at prices that look like a bargain per metre. Here is what you are buying. A rice lights 50 meter or 100 metre listing is almost always a thin single-channel string: one circuit, one controller, one plug. One failed LED or one bad joint anywhere along it takes out everything after the fault, and finding that fault in 100 metres of wire, in the dark, on the night, takes the evening. Diwali lights 100 meters outdoor listings add a second problem, because very few of them carry an IP rating at all.

A 3BHK does not need a series light 100 meter run. It needs 50 to 60 metres in five or six pieces. Three separate 20 metre strings on three sockets cover the same terrace as one 60 metre string, fail independently, and each cost ₹549 to replace rather than the whole thing. If you genuinely have a 100 metre run, a compound wall on a large plot say, buy five 20 metre IP65 strings and an extension board per pair, and accept that the electrician's hour is part of the cost.

What a budget buys, without joining anything

Series light price is mostly a function of length and IP rating. These are our lengths and prices at the time of writing, combined so that no string feeds another. Free delivery starts at ₹999.

Notice that a 10 metre string is cheaper than two 5s and a 20 is cheaper than two 10s, on top of being the better buy for the reasons below.

Why the 15% matters

You lose length at every corner where the wire has to turn, at every point where the strand sags between fixings, and most of all wherever it has to reach back to a socket. A run measured at 10 metres almost always needs an 11 or 12 metre string in practice. Buying exactly to the measurement is how people end up half a metre short at the last corner, and half a metre short looks worse than a metre spare.

Spare length is easy to hide. Double it along the top of a frame, where it reads as a brighter band, or coil it behind a curtain or a planter near the plug. Missing length cannot be hidden at all.

One long string beats two short ones

If the run is 20 metres, buy a single 20 metre string rather than two 10s wherever you can. Two strings means a visible join where one ends and the next starts, a second plug to hide, and, because factory batches drift, a real chance the two halves are a slightly different white. That difference is invisible in the box and obvious on the wall.

Two strings also cannot simply be plugged into each other. Almost no decorative series light is rated to feed a second one; the load of both goes through the first controller, which was sized for one. Where you need more than the longest length sold, the answer is separate strings on separate sockets or an extension board, and the series light connection guide covers jointers, adapters and how many strings one socket can carry. The rule is simple: if the box does not say it can be chained and how many, it cannot.

Plan the socket before you plan the string

Decorative strings have the plug at one end, and the lead from the last LED to the plug is often only 1 to 2 metres. Before you fix anything, decide which end of the run is nearest a socket and start there. If the nearest socket is 3 metres from the start of the run, that 3 metres comes out of the string, or out of an extension board.

An extension board hidden behind a plant, a curtain or a shoe rack is a perfectly good solution and is how most balconies and doors are actually done. A strand that will not reach is not a solution, and neither is a wire pinched in a sliding door track. Warm white or cool white is a separate decision, made once for the whole run, and for anything festive warm white wins.

Common mistakes

1. Estimating by room size. Perimeter is what you are buying, and a small room can have a long edge.
2. Buying to the tape. Without the 15%, the last corner is where the string ends.
3. Two short strings for one run. A join, a second plug, and two slightly different whites.
4. Plugging strings into each other. The first controller carries both loads.
5. Buying 100 metres because it was cheap per metre. One fault, one dark wall, one long evening.
6. Forgetting the plug lead. The socket decides where the run starts, not the corner you like.
7. An indoor string on an open railing. The metres were right and the IP rating was not.

The short version

How many metres of series lights do you need? Measure the edge, add 15%, round up to the next length sold. A railing is 8 to 10 metres, a window 5, a main door 6 to 7, a 2BHK 30 to 40 in three or four strings, a terrace 50 and up in several IP65 strings. Buy one long string rather than two short ones, never plug one into another, and plan the socket before the string. If you are still unsure how many metres of series lights your space takes, send a photo of it on WhatsApp and we will give you the number, including when it is fewer than you were going to buy.