Latex Floor Compound Calculator
Estimate self-levelling latex floor compound bags, coverage, waste allowance and material cost from room area, average depth, bag size and product coverage.
Calculate Latex Floor Compound
Compound Quantity Result
8 bags
18 m2 at 5 mm needs about 144.00 kg before waste, or 8 bags after allowance and rounding up.
Buy whole bags and follow the product data sheet for primer, maximum depth, mixing water, working time and substrate preparation.
Formula And Coverage Method
theoretical kg = area x depth x coverage kg per m2 per mmkg with allowance = theoretical kg x (1 + waste percentage)bags to buy = round up(kg with allowance / bag size)material cost = bags to buy x price per bagapproximate wet volume in litres = area x depthThe calculator treats the product as a powder coverage calculation, because most latex or self-levelling floor compounds are sold by bag weight and list coverage per square metre at a stated thickness. The wet volume line is a sanity check only. The real number of bags should come from the manufacturer’s kg coverage, not from water-like volume assumptions.
Average depth is usually the hardest input. A floor that is 3 mm over most of the room but 12 mm in a low corner does not behave like a neat 3 mm layer. Take several measurements with a straightedge or level, mark the worst dips, and choose an average that reflects the real pour. If depth varies a lot, split the room into zones and calculate each zone separately.
Coverage Table For A 20 kg Bag
| Area And Depth | Coverage 1.6 kg/m2/mm | Bags Before Waste | Practical Note |
|---|---|---|---|
| 10 m2 at 3 mm | 48 kg | 3 bags | Small skim coat, but primer and edge control still matter. |
| 15 m2 at 5 mm | 120 kg | 6 bags | Typical room levelling allowance before waste. |
| 20 m2 at 6 mm | 192 kg | 10 bags | Depth begins to dominate cost and mixing time. |
| 25 m2 at 10 mm | 400 kg | 20 bags | Check maximum depth and whether aggregate or another product is needed. |
Before You Buy Compound
Check The Substrate
Concrete, screed, timber boards, old adhesive, tiles and underfloor heating can need different primers and preparation. Loose, dusty or damp surfaces can cause failure even when the quantity is right.
Read Maximum And Minimum Depth
Some compounds can feather edge, while others need a minimum depth or have a maximum single-pour thickness. Deep areas may need repair mortar or a product made for thicker fills.
Plan Mixing And Pouring
Working time can be short. Count water buckets, mixing paddles, spiked roller, gauge rake, clean water and a helper before opening bags. Running out halfway through a pour can leave ridges.
Allow For Finished Floor Height
Compound depth changes door clearance, thresholds, kitchen plinths, appliance spaces and transitions to other rooms. Check finished levels before committing to a thick pour.
Worked Examples
A 12 m2 bathroom needs an average 4 mm smoothing layer. With a product coverage of 1.6 kg/m2/mm, theoretical quantity is 76.8 kg. Adding 10% gives 84.48 kg. With 20 kg bags, buy 5 bags. The spare amount is not wasted planning; it protects the pour from small dips, mixing loss and rounding.
A 22 m2 kitchen has a mostly level area but a low run near patio doors. Calculating the whole room at 8 mm may overbuy. Split it into 16 m2 at 4 mm and 6 m2 at 10 mm. The first zone needs 102.4 kg and the second needs 96 kg before allowance, so the total is 198.4 kg before waste. With 10% allowance and 20 kg bags, buy 11 bags.
A 30 m2 open-plan room at 3 mm looks modest, but it still needs 144 kg at 1.6 kg/m2/mm before allowance. That is 8 bags with 10% waste. The labour plan matters as much as the purchase plan, because many bags must be mixed and placed while edges remain workable.
Common Mistakes
Do not use one bag per room as a rule. Area and depth decide quantity. Do not ignore primer. Primer controls suction and bond, and some products require different primer treatment for porous and non-porous floors. Do not assume every grey bag has the same coverage. Fast-setting, fibre-reinforced, flexible, deep-fill and smoothing products can have different yield and depth limits.
Do not use the calculation as a structural repair plan. Cracks, movement, damp, failed screed and rotten boards need diagnosis before pouring. Covering a moving floor with compound can hide the issue for a short time and then crack. If the floor is part of a wet room, underfloor heating system or commercial space, read the full product system instructions.
Mixing Plan For Larger Pours
For anything more than a few bags, plan the pour before opening the first bag. Put clean water into measured buckets, set out bags in order, keep a second bucket for rinsing the paddle, and decide where the pour starts and ends. If the room has a doorway threshold, pipe boxing or low corner, work out how the compound will flow before it begins to thicken.
Temperature and suction can shorten working time. A warm room, thirsty substrate or slow mixing routine can leave ridges between batches. Primer, correct water quantity and steady mixing are part of the quantity plan because wasted material often comes from rushed preparation rather than from arithmetic error.
Ordering Margin
Keep at least one spare bag on site for awkward rooms, then return unopened bags only if the supplier allows it.
FAQ
How much latex compound do I need per m2?
It depends on depth and product coverage. A common planning figure is around 1.6 kg per m2 per mm, but check the bag data sheet.
Should I round up bags?
Yes. Compound is bought in whole bags, and a small shortfall during a pour is usually worse than having part of a bag left.
Can I use this for deep holes?
Only if the product permits that depth. Deep repairs may need a repair mortar, aggregate-filled product or a separate levelling method.
Does the calculator include primer?
No. It estimates compound bags and material cost. Primer, tools, edge strips and repairs should be budgeted separately.
Can I pour over timber?
Some products can be used over suitable prepared timber with the right primer or reinforcement. Follow the product instructions carefully.
Why use average depth?
The floor is rarely perfectly flat. Average depth accounts for shallow and deeper areas better than using only the thinnest layer.
Sources
- British Standards Institution. (n.d.). BS 8204 screeds, bases and in-situ floorings. BSI. https://knowledge.bsigroup.com/
- Health and Safety Executive. (n.d.). Construction health and safety. HSE. https://www.hse.gov.uk/construction/
- Tile Association. (n.d.). Technical publications and guidance. The Tile Association. https://www.tiles.org.uk/