How many coats and how many litres: a paint calculator that qualifies the lead

Paint dealers get the call asking how many litres a 2BHK needs all the time. The honest answer is that it depends, and that answer sends the caller to someone who sounds surer. A calculator on your website answers it properly: room by room, wall area less doors and windows, coats, and coverage from the product's data sheet, ending in litres and packs. Show that before asking for anything. Then offer to send it on WhatsApp, and the room sizes, painting date and phone number become a lead your counter can act on.

Why a thumb rule loses the sale

The dealer's thumb rule, so many litres for a 2BHK, treats every flat as the same flat. It ignores ceiling height, the number of windows, new plaster that drinks the first coat, and a repaint in the same shade that needs less. A buyer who goes by it either over-buys and stores tins in the loft, or runs short halfway and orders a second batch of a tinted shade that may not match the first.

A calculator that asks room by room gives a better answer. It also tells you more about the job than most phone calls do.

The arithmetic behind it

Wall area   = 2 x (length + width) x height
Paintable   = wall area - doors - windows (+ ceiling, if painted)
Litres      = paintable area x coats / coverage per litre per coat
To buy      = litres, rounded up to the packs you stock

Coverage comes from the product's data sheet, and the sheet quotes it for a smooth, primed surface. Real walls are seldom that smooth. So show a range: the data-sheet figure at one end, and a lower figure for rough or porous walls at the other. Add a line telling the buyer which end their wall is likely to sit at.

For example, take a bedroom 12 ft by 10 ft with a 10 ft ceiling. The walls come to 2 x 22 x 10, or 440 sq ft. Take off a 7 by 3 ft door and a 4 by 4 ft window and about 403 sq ft is left. Two coats make 806 sq ft. Suppose the data sheet said 100 sq ft per litre per coat, a round figure chosen for the arithmetic and not taken from any product. The room then needs a little over 8 litres, and the calculator would suggest a 10-litre pack.

What the calculator asks, screen by screen

1. Rooms. Bedroom, hall, kitchen, bathroom ceiling, with length, width and height for each. Offer "I only know the flat size" as a shortcut that returns a wider range.
2. Doors and windows. A count per room, with a standard size the buyer can change.
3. Wall condition. New plaster, repaint in the same colour, light over dark, or damp and peeling patches. The last one gets no litre figure. It gets a line saying the wall needs looking at first, and a link to a page like why a leak needs an assessment before a cart.
4. Product. Picked from your own range, so the coverage loads from that product's data sheet. Ceiling paint is chosen separately.
5. Coats. Two by default, with a note that a big change of colour or new plaster may need a third. Primer and putty appear as their own lines.
6. Result. Litres as a range, the pack combination with the least left over, and one sentence: "This is an estimate. Your painter's measurement on site is final."
7. Then, and only then, the ask. "Send me this estimate on WhatsApp", with name, mobile number, pin code, when they plan to paint, and "Do you have a painter?" yes or no.

How the last screen qualifies the lead

Each field tells the counter something. The pin code says whether you deliver there or which dealer should take it. The painting date separates "before Diwali" from "some time next year". "No painter" is a second sale, if you work with painting contractors and the buyer agrees to an introduction. The total area from the earlier screens says whether this is one room or a whole house, and the wall condition says whether a visit comes before any paint.

Give the counter one rule. A whole house, a date within the month and no painter goes to the top of the counter's call list. A single room with a painter already booked gets the WhatsApp estimate and a cart link, and nothing more unless they reply.

For example: a Lucknow dealer and the number asked too soon

Imagine an invented paint dealer in Lucknow, with every figure made up, who adds a calculator to the website. Its first screen is a mobile number field: "Enter your number to see the estimate." Plenty of visitors leave right there. The ones who stay type ten nines. The counter calls a list of numbers that never ring, decides calculators do not work, and stops looking at the page.

The mistake was asking before giving. The dealer moved the number to the end, after the litre range, and asked for it only to send the estimate. Two questions went in beside it: when, and whether a painter is booked. Each lead now arrives with room sizes and a date, so the counter knows which ones to ring first. Of 60 people who finished the calculator in the first month, about 25 left a number, and the counter reached around 15 of those. That is fewer leads than the number-first form promised, and the dealer had paid ₹15,000 for the page build, so the early months looked poor. But the 15 were real, and a few were whole-house jobs.

When not to build one

If nobody at the counter will call the leads, do not build it. An estimate with no follow-up is a free tool for a buyer who then orders elsewhere. Skip it as well if most of your buyers are painting contractors, who measure for themselves and want a price list. And keep it inside your own range: a calculator that recommends no product of yours teaches the buyer the quantity and sends them off to compare prices.

Listen to the counter first

Ask whoever answers your phone how they handle "how many litres?" today. If the answer is a thumb rule, the calculator replaces it and hands you the lead as well. Decide who gets called first before any page is built. Landing page development is the work of building the page itself, and retail is the wider section for counters like yours. For the page and the follow-up behind it, tell us what you need.