Self-Levelling Compound Calculator – Bags, Depth & Cost

MEASURE · LEVEL · PLAN

Self-levelling compound calculator: bags, depths and costs

Use this free self-levelling compound calculator to estimate floor leveller for a single room or a larger project. Enter each floor area and its required depth, check the coverage for your chosen product and see the whole bags or complete kits needed. It supports Metric and Imperial measurements, existing stock, optional primer quantities and a printable project estimate.

Self-levelling, self-leveling, floor smoothing compound and liquid leveller describe related products, but their coverage and application requirements differ. This tool calculates quantities from the values you enter. It does not choose a product, approve a substrate or establish how quickly the floor can receive its final covering.

How to use the calculator

1. Choose units and enter the specified project depth. A project name and currency selection are useful if you want a priced printout.
2. Add rooms or floor zones. Choose Rectangle, Triangle, Circle or Direct area, enter measurements and deduct any area that will not be treated. Quantity repeats both the area and its deduction.
3. Use the optional depth settings for areas with a different thickness. A rectangular linear taper can use the depths at two opposite edges.
4. Check the manufacturer’s coverage per bag or kit at a stated thickness. Alternatively, enter powder consumption per area per depth and the powder bag weight.
5. Add a deliberate waste allowance and any usable whole units already on site. Primer, mixing liquid and prices are optional.
6. Calculate, review the area breakdown and whole purchases, then open Print / Save PDF for a result-only estimate.

How many bags of self-levelling compound do I need?

The coverage method calculates each area’s share of a bag by dividing its net area by the stated coverage and adjusting for applied depth relative to the reference depth. The shares are added together, your waste allowance is applied, and the project total is rounded up once. This avoids over-ordering caused by rounding every room separately when all rooms use the same product.

For example, a 5 m × 4 m floor is 20 m². At 3 mm depth, with a product covering 6 m² per bag at 3 mm, it needs 20 ÷ 6 = 3.333 bags before waste. At 10% waste it needs 3.667 bags, so the whole requirement is 4. With one usable bag already on site, buy 3 new bags. This is an arithmetic example, not a universal product coverage.

Manufacturer coverage and consumption

The editable starting reference is approximately 6 m² at 3 mm from a 25 kg bag of Mapei Ultraplan Renovation Screed 3240. Confirm the current local product sheet before using that reference. Other products can be supplied as a powder bag plus liquid: ARDITEX NA, for example, lists a complete-unit coverage of approximately 5 m² at 3 mm. A bag alone and a complete kit are not interchangeable purchasing descriptions.

Consult the Mapei product information and the ARDEX ARDITEX NA product information for their respective specifications. Enter the coverage, price and powder weight that match the unit you are actually buying. This calculator uses one compound product per estimate; different product systems should have separate estimates.

If your data sheet provides powder consumption, choose that method instead. The calculation multiplies net area by depth and powder consumption, then divides by powder weight per bag. Powder consumption is not the same as wet density. Do not substitute a generic concrete density or a guessed value from another levelling product.

Measuring floors with different depths

A small depth change across a large floor can materially change the order. Measure representative zones and use an average thickness appropriate to each zone. Entering the deepest hollow as the depth for an entire room usually overstates the volume. Conversely, overlooking deeper patches can lead to a shortage.

For a rectangular floor whose required thickness changes evenly between two opposite edges, the mean of those two thicknesses gives the average depth. That shortcut does not model irregular dips, ridges, curved profiles or an uneven triangular floor. Divide those into measured zones instead. Any area deducted from a tapered rectangle is assumed to have the same average depth as the remaining floor; use separate zones if the omitted patch has a different depth.

Primer, mixing liquid and existing stock

Primer requirements depend on the product, substrate, dilution and number of coats. The optional primer section uses net floor area, its own coat count and its own waste allowance. Enter coverage per unit of primer as purchased, allowing for permitted dilution, then enter the pack size. The tool rounds up the total primer packs. It does not assume that every levelling compound needs the same primer or the same treatment.

The mixing-liquid option is a planning total for all whole units required, including any stock used. Enter the exact manufacturer-specified liquid quantity per complete bag or kit. It does not authorize extra water, replacement of a supplied additive or partial-batch mixing. If the liquid comes with the kit, include it in the kit price rather than adding it again as a separate material cost.

Only enter existing stock that is usable, the same product and complete. Stock reduces the new purchase quantity. Its historic cost is not included in the job cost shown here; add an explicit allowance in Other costs if your pricing method needs to recover it.

Optional labour and job pricing

All prices start at zero so DIY users can estimate materials without entering business information. Tradespeople can add bag and primer prices, one labour method, preparation, equipment, delivery and other job costs. Area-based labour uses net floor area without compound waste. Time-based labour uses the hours or days you enter.

Markup is a percentage added to total cost. For example, a cost of 200 with 20% markup becomes 240 before tax. Entering 20% tax then produces 288. These are illustrative figures, not suggested rates or tax advice. Currency changes symbols only. Closing an optional section retains its values; set an unwanted price back to zero or select None for labour.

Frequently asked questions

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