# Paint Quantity Calculator Litres required from area and coats, the tin sizes that make up the quantity, the primer, and an estimated cost. Published: 2026-09-06 · Last updated: 2026-09-30 ## Contents 1. Worked example 2. Short answer 3. Spreading rate is a range, not a number 4. Measuring the area honestly 5. How many coats 6. Primer: when it saves money 7. Tin sizes and the batch problem 8. What to send us for a quote ## Calculator From square metres and coats to litres, the tin sizes that make up the quantity, and the primer. Note: This page contains an in-browser calculator; results are computed instantly from your inputs and no data is sent to a server. The full method is explained below. ## Worked example Opened with its default case — **Calculation method: I know the area to be painted · Area to be painted (m²): 100 · Deduction for doors and windows (m²): 0** — the calculator returns the figures below. They are written out here so the output is readable without running JavaScript: in print, with scripts disabled, or by a search engine. Worked example — inputs | Input | Value | | --- | --- | | Calculation method | I know the area to be painted | | Area to be painted (m²) | 100 | | Deduction for doors and windows (m²) | 0 | | Paint type | Interior silicone matt (11–15 m²/L) | | Number of coats | 2 | | Allowance for waste (%) | 8 | | Include primer in the calculation | Yes | | Paint unit price (TRY/litre) | 0 | Worked example — results | Result | Value | | --- | --- | | Net area to be painted | 100 m² | | Paint required | 14.4 – 19.6 L | | Tin sizes to buy | 1 × 15 L + 2 × 2.5 L | | Primer required | 7.7 – 10.8 L (water-based wall primer) | | Estimated paint cost | Enter a price | Change any field above and the calculator recomputes; this table is the default case only. ## How much paint do I need? **Litres = area (m²) × coats ÷ spreading rate (m²/L), plus a waste allowance.** The number that decides the answer is the **spreading rate**, and it is a range rather than a figure: interior emulsion covers roughly 14–18 m² per litre, interior silicone matt 11–15, exterior acrylic 7–10, oil-based gloss 18–20 (manufacturers’ datasheets, one coat). A 4 × 5 m room with 2.8 m ceilings has 50.4 m² of wall; at two coats of silicone matt that is **7.3 to 9.9 litres** with an 8% waste allowance — so one 7.5 L tin plus one 2.5 L, not a single 15 L pail. Plan against the *upper* end of the litre range: manufacturers give spreading rates “depending on the surface”, and porous, rough or newly plastered walls sit at the low end of the m²/L range or below it. ## Spreading rate is a range, not a number Typical spreading rates by paint type | Paint type | Spreading rate (m²/L) | Where the range comes from | | --- | --- | --- | | Interior emulsion / matt | 14–18 | Substrate porosity; matt finishes are the most forgiving | | Interior silicone matt | 11–15 | Surface; this product class is often sold by kg (e.g. 7–10 m²/kg) | | Exterior acrylic | 7–10 | Surface texture — render and pebbledash consume far more | | Synthetic gloss, oil-based | 18–20 | Applied thin over a primed surface; the primer does the filling | | Water-based wall primer | 10–14 | Absorbency of the bare substrate | | Alkyd primer (under oil-based paint) | 13–16 | Substrate and film build | Rates are one-coat datasheet figures from Turkish manufacturers (DYO, Filli Boya). Manufacturers give them “depending on the surface”: new plaster, filler patches and previously unpainted masonry sit at the low end of the range or below it, which is exactly the case where a primer is cheaper than budgeting extra topcoat. DYO’s own consumer guide puts 15 L of interior paint at roughly 60–80 m² over two coats in practice. ## Measuring the area honestly Wall area is the room perimeter multiplied by the height: **2 × (width + length) × height**. Add the floor area again if the ceiling is being painted. Then decide on openings: for your own purchase, not deducting ordinary doors and windows leaves a margin for waste and touch-ups (DYO’s guide advises non-professionals not to deduct them), while large glazing such as shop fronts should always come off. The waste allowance is not padding. Roller tray residue, brush loading, the film left in the tin and ordinary spillage account for 5–10% on a normal job, and more where there is a lot of cutting-in or spray application. Running out mid-wall costs more than the allowance ever does — see the batch problem below. ## How many coats Choosing the coat count | Situation | Coats | Note | | --- | --- | --- | | Repaint in the same colour | 1 | Only if the existing finish is sound and evenly coloured | | Repaint in a similar colour | 2 | The normal case | | Light over dark, or a strong colour | 2 + primer | A tinted primer beats a third topcoat on both cost and finish | | New plaster or bare substrate | Mist coat + 2 | The mist coat is thinned paint that seals the surface | | Strong colours (red, deep yellow) | 3 or tinted primer | The pigments have low opacity; this is a property of the colour, not the brand | One coat over two is not a saving if the finish is patchy — the remedial coat costs the labour again as well as the paint. ## Primer: when it saves money Primer is often treated as an optional extra and is frequently the cheapest litre on the job. It earns its place in four situations: a bare or newly plastered surface, where it stops the topcoat being drunk by the substrate; a large colour change, where a tinted primer replaces a whole topcoat; a glossy or previously oil-painted surface, where it provides adhesion the topcoat cannot get on its own; and stained or repaired areas, where it blocks the stain from bleeding through. Outside those cases, over a sound painted wall in a similar colour, it can usually be skipped. ## Tin sizes and the batch problem The calculator converts litres into the tin sizes that make up the quantity, filling from the largest down and then adding the smallest single tin that covers the remainder. Buying the right combination matters for a reason beyond price: **tinted colours vary slightly between production batches**. Two tins mixed at different times can differ enough to show on a long wall in daylight. Two rules follow. Buy the whole quantity for a continuous surface at once and check that the batch number matches across the tins. And where a wall is large enough to need more than one tin, box the paint — combine the tins in a larger container and stir — before starting, so any variation is spread evenly instead of appearing as a line where one tin ran out. ## What to send us for a quote Send the calculator output with the substrate (new plaster, previously painted, render, metal), the finish you want and the colour reference if you have one. Substrate and finish are what decide the product, and the colour decides whether a tinted primer is worth it. We quote paint, primer, rollers, brushes, trays, masking tape and dust sheets as one list, delivered to site. ## Frequently Asked Questions How many litres of paint for a 4 × 5 metre room? With 2.8 m ceilings the walls are about 50 m². Two coats of interior silicone matt at 11–15 m²/L with an 8% allowance is roughly 7.3 to 9.9 litres — one 7.5 L tin plus one 2.5 L. Add about 20 m² again if the ceiling is included. Why does the calculator give a range instead of one number? Because spreading rate is a range. The same paint covers 15 m² per litre on a smooth sealed wall and 11 on a porous or textured one. Buy against the upper end of the litre range; the alternative is running out with one wall left. Should I subtract doors and windows from the area? For your own purchase, leave ordinary doors and windows in: the margin covers waste and touch-ups, and DYO’s consumer guide gives the same advice to non-professionals. Always deduct large glazing such as shop fronts. Do I need primer over an already painted wall? Usually not, if the existing finish is sound and the new colour is similar. Primer earns its cost on bare or new plaster, over gloss or oil paint, on stained or patched areas, and on a large colour change — where a tinted primer is cheaper than a third topcoat. Why do two tins of the same colour look different? Batch variation in tinting. Buy the full quantity for one continuous surface together, check the batch numbers match, and box the tins — combine and stir them before starting — so any difference is spread across the wall rather than showing as a line. Can you supply the paint and the application materials together? Yes — paint, primer, rollers, sleeves, brushes, trays, masking tape, filler and dust sheets on one quote and one invoice, delivered to site. Send the calculator output with the substrate and colour and it comes back within one business day. ## Sources 1. [DYO Dinamik Mat — product datasheet (14–18 m²/L)](https://dekoratif.dyo.com.tr/urunler/ic-cephe-urunler/dinamik-mat) 2. [DYO Beşyıldız Silikonlu Mat — product datasheet (11–15 m²/L; 7–10 m²/kg)](https://dekoratif.dyo.com.tr/urunler/ic-cephe-urunler/besyildiz-silikonlu-mat) 3. [DYO Dyosil exterior — product datasheet (7–10 m²/L)](https://dekoratif.dyo.com.tr/urunler/dis-cephe-urunler/dyosil) 4. [DYO Beşyıldız silicone primer — product datasheet (10–14 m²/L)](https://dekoratif.dyo.com.tr/urunler/astarlar-macunlar-ve-tinerler/besyildiz-silikonlu-icdis-cephe-astar) 5. [DYO Kivastar alkyd primer — product datasheet (13–16 m²/L)](https://dekoratif.dyo.com.tr/urunler/astarlar-macunlar-ve-tinerler/kivastar-sentetik-astar) 6. [Filli Boya oil-based gloss — technical data sheet (PDF; 18–20 m²/L)](https://www.filliboya.com/uploads/TDS_FI%CC%87LLI%CC%87YAG%CC%86LIPARLAK.pdf) 7. [DYO consumer guide — how much paint for a room (15 L ≈ 60–80 m² over two coats in practice)](https://dekoratif.dyo.com.tr/dyoblog/renk-ve-dekorasyon/ne-kadar-boya-gider-oda-ve-ev-icin-boya-hesaplama-rehberi) How we choose sources, verify figures and date our pages is set out in [how we source and verify what we publish](https://aksco.com.tr/en/editorial-standards/). Spotted an error? Write to [info@aksco.com.tr](mailto:info@aksco.com.tr) — verified errors are corrected. ## Related guides ### Paint & Building Materials Paint, primer, filler, rollers, brushes and site protection. [Read more](https://aksco.com.tr/en/products/paint-building-materials/) ### New Office Setup: What to Buy, and in What Order Where decoration sits in the fit-out sequence. [Read more](https://aksco.com.tr/en/insights/new-office-setup-checklist/) ### Site Mobilisation Checklist What has to be on site before work starts. [Read more](https://aksco.com.tr/en/insights/site-mobilization-checklist/) ## Send your list — your quote is ready within 1 business day. A list, a photo or an Excel file — whatever is easiest. On standard items most quotes go out the same business day. Custom production, imports or 50+ line lists can take longer; when they do, we tell you the timeline in writing on the day we receive the request. [Request a Quote](https://aksco.com.tr/en/request-a-quote/)[Message on WhatsApp](https://wa.me/905343356922) --- AKSCO Ticaret ve Tedarik — https://aksco.com.tr AKSCO Ticaret ve Tedarik · Esentepe Mah. Talat Paşa Cad. No:5 İç Kapı No:1, Şişli/İstanbul Türkiye'nin 81 ili ve uluslararası sevkiyat info@aksco.com.tr · 0534 335 69 22