HomeCalc FAQ
Questions and answers about the home and property calculators. Everything they work out happens in your browser.
Last Updated: November 9, 2026
1. General Questions
Q1: What is HomeCalc?
A1: Seven calculators for building, doing up and renting a home: your rooms, paint and wallpaper, tiles and flooring, cement, sand and bricks, property area and price, a renovation budget, and the rent you can afford. You measure your rooms once, and the paint, wallpaper, tile and plaster calculators can use some or all of them. Each answer is a shopping list in the units shops sell, and each one shows how it is worked out.
Q2: How much does it cost?
A2: Nothing. It is free, with no registration and no limit. Like every page on ZeroDataUpload, it is supported by advertising.
Q3: Do I need to install anything or create an account?
A3: No. Open the page in any modern browser (Chrome, Edge, Firefox, Safari or Opera) on a computer, tablet or phone. What you type is kept in that browser, so there is nothing to sign in to.
Q4: Is anything I type uploaded?
A4: No. Sizes, prices and amounts are worked out by this browser on your device and never sent to a server. The page itself loads the site's ads and analytics, as every page on the site does; the Privacy Policy explains those, and your figures are never part of them.
Q5: Who is it for?
A5: Anyone doing up a flat or building a house who wants to know what to buy before going to the shop or talking to a contractor; anyone comparing flats by the area they really get; and anyone working out the rent they can afford. A contractor can use it to check quantities too.
Q6: Can I measure in feet or in metres?
A6: Both. Choose Feet or Metres at the top of the tool (or press U). Every box still takes any unit you type, and switching converts what you have typed. Areas follow: square feet or square metres.
2. Typing Measurements and Amounts
Q7: What can I type as a length?
A7: A plain number in feet or metres (whichever you chose), or a length with its unit: 12'6", 12 ft 6 in, 12ft6, 3.8 m, 380 cm, 3800 mm, 150 in or 4 yd, and sums such as 10' + 4'6". Lengths over 10 km are refused as a typing mistake.
Q8: What can I type as an area?
A8: A plain number in square feet or square metres, or an area with its unit: 1200 sq ft, 111.5 sq m, 150 gaj or sq yards, 2 guntha, 10 cent, 1 ground, 1 acre or 0.5 hectare, and sums such as 2 guntha + 10 cent. Bigha and marla are not taken, because they mean different areas in different states.
Q9: What can I type as an amount?
A9: Digits with or without commas (45000, 45,000 or 1,45,000), with k, L, lakh, cr or crore (45k, 1.5L, 1.2 cr), sums such as 450 + 300 or 150 x 22, and a rupee sign or a code in front (Rs500, Rs. 500, AED 250). Amounts over 10 lakh crore are refused.
Q10: What does the line under a box say?
A10: What HomeCalc understood: a length typed in feet is shown in metres and the other way round, and 1.5L is shown as 1,50,000. If it says the value cannot be read, the box is left out of the answer until it is fixed.
3. Rooms
Q11: How do I add my rooms?
A11: Press Add a room, name it and choose its shape: a rectangle, an L-shape (a rectangle with one corner missing), round, a triangle, or Other for a floor area you already know. Type its sizes, the height (empty uses the usual ceiling height from Settings) and the number of doors and windows. Each room is drawn as a plan with its floor area, the walls to paint and the distance around it.
Q12: What are the 1, 2 and 3 BHK examples?
A12: Starting points with example room sizes in feet, so you do not have to add every room by hand. They are not a survey of Indian flats: change each size to your own home. You can add an example's rooms to the ones you have or replace them.
Q13: How are doors and windows taken off the walls?
A13: Each door and window is taken off at the usual sizes in Settings (a door 3 by 7 ft and a window 4 by 4 ft to start with; change them to yours). Wardrobes, tiled walls or anything else you will not paint go under Walls not painted.
Q14: How do the other calculators use my rooms?
A14: Paint, wallpaper, tiles and plaster each have My rooms, where you tick the rooms to include. Paint these rooms, Tile these floors and Use as carpet area, under the rooms' totals, open those calculators already set to your rooms. A change to a room reaches every calculator.
4. Paint and Wallpaper
Q15: How much paint do I need?
A15: The walls are the distance around the room times its height, less the doors and windows, plus the ceiling if you paint it. The litres are that area times the number of coats, divided by what one litre covers in one coat, plus the extra you set for spills and touch-ups (10% to start with).
Q16: What coverage should I type?
A16: The figure printed on your tin. Indian paint makers print what one litre covers in two coats, so leave "Coverage is for" on 2 coats when you copy it. The starting figures are the lower end of a large Indian maker's product sheets: interior emulsion 130 sq ft a litre for two coats, premium emulsion 140, exterior emulsion 55 and gloss enamel 95. Rough or porous walls take more.
Q17: Do I need primer and putty?
A17: Choose what the walls are like and HomeCalc ticks what usually goes with it: a repaint in the same colour needs neither, a new colour needs primer, dark to light needs primer and a third coat, and new plaster needs putty and primer. The starting coverage is primer 215 sq ft a litre in one coat and putty 16 sq ft a kg in two coats, the lower end of Indian makers' product sheets; use the figures on your own tin and bag.
Q18: How are the tins to buy chosen?
A18: From the sizes you list (1, 4, 10 and 20 litres to start with), HomeCalc finds the mix that holds enough paint for the least money, then the fewest tins. Type the price of each size for an exact answer; until then it assumes, as shops do, that a bigger tin costs a little less per litre.
Q19: How many wallpaper rolls do I need?
A19: Each strip is the wall height plus 10 cm for trimming, rounded up to the pattern repeat (with half a repeat more for a half-drop pattern). Each wall needs its width divided by the roll width in strips, rounded up, and a door saves the strips that fit across it. The rolls are the strips divided by the strips one roll gives, rounded up, plus the spare rolls you choose.
Q20: How much wallpaper paste do I need?
A20: The packet says how many rolls it hangs, so type that number and HomeCalc counts the packets. Pastes differ, so it does not guess.
5. Tiles and Flooring
Q21: How does HomeCalc count tiles?
A21: For a rectangular floor or wall laid straight, it lays the tiles out the way a tiler does and draws them: the whole tiles, the cut pieces at the walls, and thin pieces cut several from one tile (3 mm is lost to each cut). Other shapes and patterns are counted by area, with an allowance for cuts.
Q22: Should the tiles start in a corner or be centred?
A22: From a corner gives whole tiles along two walls and one cut at each of the others. Centred puts the pattern in the middle of the room, so the cuts at opposite walls are equal and thin strips are avoided, though it can use a few more tiles. HomeCalc warns about thin strips and offers to centre the tiles when that helps.
Q23: How much extra is added for cuts and breakage?
A23: A floor that is not a rectangle, or a pattern other than straight, is counted by area plus 10% for cuts laid straight or as bricks, 15% diagonally and 20% in herringbone, the allowances tile sellers suggest. On top of that comes the spare for breakage (5% to start with), so a few tiles are left for repairs.
Q24: How many boxes do I need?
A24: The total number of tiles divided by the number in a box, rounded up. The number in a box is printed on it; HomeCalc fills it in only for the sizes where a large Indian maker's catalogue states it (4 for 600 x 600, 2 for 600 x 1200 and 2 for 800 x 1600), and you type it for the others.
Q25: How much adhesive, grout or mortar?
A25: Adhesive: type what one bag covers, printed on the bag for your tile size and trowel, and HomeCalc counts the bags. Grout uses the grout makers' formula, (A + B) / (A x B) x joint width x tile thickness x 1.6 kg per square metre, plus 10%. A mortar bed is 20 mm of 1 : 4 with grey cement slurry at 3.3 kg a square metre, as the public works specification for vitrified tiles has it.
Q26: Can it work out the skirting too?
A26: Yes. Skirting is cut from the same tiles along the walls, less the doorways: HomeCalc counts how many strips of your skirting height one tile gives and adds those tiles to the total.
6. Cement, Sand and Bricks
Q27: How is the concrete worked out?
A27: The volume of each slab, footing, column, beam or staircase, plus the extra you set for spills, is the wet concrete. The dry materials take about 1.54 times that volume, split by the mix (M20 is 1 : 1.5 : 3). Cement weighs 1,440 kg a cubic metre, so a 50 kg bag is 0.0347 cubic metres. Sand and aggregate are given in cubic feet, brass and tonnes.
Q28: Why is there no M25?
A28: IS 456, the Indian code for concrete, allows concrete mixed by proportion only up to M20. M25 and stronger grades need a designed mix from a lab or a ready-mix plant, so HomeCalc offers M5 to M20.
Q29: How much water does the concrete need?
A29: HomeCalc shows the most water IS 456 allows for the grade, per 50 kg bag of cement: 60 litres for M5, 45 for M7.5, 34 for M10, 32 for M15 and 30 for M20. More water makes concrete easier to pour but weaker.
Q30: Why does it not work out the steel?
A30: Rules of thumb for steel per cubic metre differ by twice from one source to the next. The weight comes from the bar schedule on your structural drawing: type it in kg per cubic metre under The mix and the steel joins the list.
Q31: How many bricks or blocks do I need?
A31: A wall one brick thick is counted by volume: the wall's volume divided by a brick with its mortar joint on every side. A wall half a brick or one block thick is counted by its face. A modular brick wall with 10 mm joints comes to 500 bricks a cubic metre. The mortar is the wall less the bricks; its dry materials take 1.33 times that, plus 10%.
Q32: What is a brass?
A32: A unit sand and aggregate are sold by in much of India: 100 cubic feet, about 2.83 cubic metres. HomeCalc gives sand and aggregate in cubic feet, brass, tonnes and cubic metres.
7. Property Area and Price
Q33: What are carpet, built-up and super built-up area?
A33: Carpet area is the floor inside the flat's walls, counting the inside walls but not the outer walls, shafts, your own balconies or terraces; under RERA (2016) it is the area builders must state. Built-up adds the outer walls and balconies. Super built-up adds your share of the lobbies, stairs, lifts and clubhouse.
Q34: What is loading?
A34: How much the super built-up area is more than the carpet area. ANAROCK found it was 40% on average in India's seven largest cities in early 2025, so 1,400 sq ft super built-up was about 1,000 sq ft of carpet. HomeCalc starts from 40%; type the figure for your flat.
Q35: Which price per square foot should I compare?
A35: The price per square foot of carpet area, the floor you can use. Two flats quoted at the same rate on super built-up area can give very different carpet areas. HomeCalc shows the price on each area and the all-in price per square foot of carpet.
Q36: How are GST, stamp duty and registration added?
A36: GST is 5% on a flat bought under construction, 1% on an affordable one (up to 60 sq m of carpet in a metro city or 90 sq m elsewhere, and up to 45 lakh), and none on a ready flat with its completion certificate. Stamp duty and registration differ by state, and some states charge women buyers less, so type your state's rates.
Q37: How much is a guntha, a cent or a ground?
A37: A guntha is 33 by 33 feet: 1,089 sq ft, 121 sq yd or 101.17 sq m, and 40 gunthas make an acre. A cent is a hundredth of an acre, 435.6 sq ft. A ground, used in Tamil Nadu, is 2,400 sq ft. Land and area units, under Property area, converts between these, square feet, square metres, square yards, acres and hectares.
8. Budget and Rent
Q38: How does the renovation budget work?
A38: Each item has a category, a quantity, a unit, a rate and what you have paid. HomeCalc adds them up with a buffer for surprises, shows what is left of your budget and what is still to pay, and draws where the money goes. Paint, wallpaper, tiles and cement send their shopping lists with Add to budget, replacing what they sent before. Save it as a spreadsheet or print it.
Q39: Why do the lists of items have no prices?
A39: Prices for a modular kitchen or a bathroom differ a great deal by city, material and contractor, and there is no figure that holds everywhere. The lists give you the items to think of; type the rates from the quotes you get.
Q40: How much rent can I afford?
A40: HomeCalc sets two limits and takes the lower: a share of your take-home pay (30% is a common rule of thumb; you can choose 25, 40 or 50%), and what is left after your loan EMIs, other fixed costs, the savings you want, living costs and the flat's bills.
Q41: What does checking a flat show?
A41: The rent with maintenance a month and its share of your pay, whether it fits, the cash to move in (the deposit and brokerage in months of rent, the first month and moving costs), and the rent in the second and third years with the yearly rise you type.
Q42: How much deposit can a landlord ask for?
A42: The Model Tenancy Act (2021) caps the deposit for a home at two months' rent, but only in the states that have adopted it. Elsewhere it is what you agree. Type the months for each flat you look at.
9. Your Data
Q43: Where is my data kept?
A43: In this browser's storage on this device, so it is there next time. Nothing is written until you type or choose something, and a private window or cleared browser data starts empty.
Q44: How do I move it to another device or keep a copy?
A44: Settings, Your data: Save a backup writes everything to a file; Open a backup on the other device replaces what is there with it, after you confirm. Files over 10 MB are refused, and every value in a backup is checked before it is used.
Q45: How do I delete everything?
A45: Settings, Your data, Delete everything, after you confirm. It removes HomeCalc's data from this browser and leaves the rest of the site alone.
Q46: I used HomeCalc before. Is my data still there?
A46: Rooms and calculators saved by the earlier HomeCalc in this same browser are brought over the first time the page opens. Its own light and dark setting is not: the site's sun and moon button sets the theme.
Still have a question?
The help page walks through every calculator. For anything else, use the contact form.