How do you use this tool?
- Pick the input mode: enter wall area directly, or build it up via length × height × wall count.
- Choose the substrate: concrete, clay brick, aerated concrete, sand-lime brick, or ETICS plaster carrier. Layer thickness snaps to the DIN V 18550-1 default — override freely if your measurement differs.
- Pick the plaster type: lime, lime-cement, cement, gypsum, rendered/structure, or natural-lime restoration plaster for old-building refurbishment.
- Set the wastage factor 0–20 % (default 10 %) and pick sack size 25 / 40 kg.
- Output: plaster volume in litres, dry mix in kg, rounded-up sack count, and mixing water per sack plus per batch. Copy the shopping list or download an A4/Letter/A5 PDF.
What does this calculator do?
The plaster calculator gives you plaster volume, sack count, mixing water per sack, and a print-ready A4 material list for your wall area. It knows six plaster types with real datasheet densities, five substrate types with DIN V 18550-1 standard layer thicknesses, and automatically follows the right layer thickness when you change substrate. All computations run locally in the browser — no upload, no tracking, no data leaves your device.
Five differentiating features no other online calculator offers together: pure-client without login and without ads for the actual calculation; DIN V 18550-1 substrate toggle that sets layer thickness automatically per substrate (concrete 15 mm / aerated concrete 10 mm / clay brick 20 mm); mixing-water calculation per sack and per batch from datasheet values of 0.16–0.40 L/kg; natural-lime restoration plaster as its own plaster type per WTA bulletin 2-9-04; and sibling cross-link to the mortar calculator plus print-ready PDF material list for the masonry supplier as A4, Letter or A5.
The calculator follows DIN EN 998-1 for plaster-mortar classes (CS I/II/III/IV), DIN V 18550-1 for planning and execution of interior and exterior plasters, and WTA bulletin 2-9-04 for the restoration-plaster pathway.
Do you also need masonry mortar?
This tool focuses on plaster mortar as a full-wall coating. For masonry mortar between stones — bed and head joints, mortar groups M5/M10/M15, first-row levelling — the mortar calculator is the sibling tool. Both are DIN-compliant and pure-client. Workflow: first plan the masonry with the mortar calculator, then here compute the coating. Three clicks there, a few inputs here, finished shopping list for the supplier run.
Which six plaster types does the calculator know?
| Plaster type | Density (kg/L) | Water (L/kg) | Layer | Application |
|---|---|---|---|---|
| Lime plaster | 1.5 | 0.20 | 15 mm | Old-building interiors, breathable walls |
| Lime-cement plaster | 1.6 | 0.18 | 15 mm | Universal interior + exterior (CS II) |
| Cement plaster | 1.7 | 0.16 | 20 mm | Socle, wet rooms, basements (CS III/IV) |
| Gypsum plaster | 0.95 | 0.40 | 10 mm | Interior, wallpaper-ready (not wet rooms) |
| Rendered/structure plaster | 1.4 | 0.22 | 5 mm | Exterior finish coat, 2–5 mm grain |
| Natural-lime restoration plaster | 1.45 | 0.25 | 25 mm | Salt-loaded existing walls (WTA 2-9-04) |
The first five pathways are market standard. Natural-lime restoration plaster is the specialty pathway for the 2026 renovation boom — on damp, salt-loaded old-building walls regular lime or cement plaster is contraindicated, because salts crystallise at the surface and damage the plaster. The high pore volume of restoration plaster (>40 vol-%) relocates crystallisation into the pore space, the wall stays diffusion-open.
How does the substrate toggle work?
When you switch substrate, layer thickness snaps automatically to the DIN V 18550-1 standard for that substrate. You can override freely — the auto-setting is just the recommendation:
| Substrate | Default thickness | Note |
|---|---|---|
| Concrete (reinforced) | 15 mm | Bonding bridge / spritz coat usually required |
| Clay brick / perforated brick | 20 mm | Classical value for uneven visible surfaces |
| Aerated concrete | 10 mm | Highly absorbent, pre-wet evenly |
| Sand-lime brick | 12 mm | Smooth planblocks require a bonding bridge |
| ETICS plaster carrier | 8 mm | Reinforcement layer + mesh mandatory |
These values are the DIN V 18550-1 recommendations — they cover about 90 % of DACH-region practice. For very uneven substrates or special situations (two-pass build-up of base + finish coat, very smooth visible concrete) higher values apply; write them directly into the layer-thickness input.
How much mixing water per sack?
Mixing water is the variable most plaster calculators omit — but on-site logistics depend on it. From datasheet values:
| Sack size | Lime | Lime-cement | Cement | Gypsum | Rendered | Restoration lime |
|---|---|---|---|---|---|---|
| 25 kg | 5.0 L | 4.5 L | 4.0 L | 10.0 L | 5.5 L | 6.25 L |
| 40 kg | 8.0 L | 7.2 L | 6.4 L | 16.0 L | 8.8 L | 10.0 L |
For 10 × 25-kg sacks of lime plaster that’s 50 L of mixing water for the entire batch — on construction sites without water hookup quickly a bottleneck. The calculator shows per-sack and total water directly.
What does the tool NOT calculate?
Intentionally omitted to keep scope and liability clean:
- No cost / €-per-m² estimate. Prices vary regionally and by manufacturer; sack count yes, price no.
- No product / vendor database. Generic plaster classes, no SKUs — neutral and long-term stable.
- No camera/AR photo measurement. Pure-client and privacy hard-cap rule it out.
- No multi-layer build-ups (base + finish coat separate). Phase 1 keeps the single-layer model lean; multi-layer mode follows if demand emerges.
- No 3D wall visualisation / sketch output. Maximalism effect, not in refined-minimalism scope.
- No structural / load-bearing design. Plaster carries no load; structural design belongs to a structural engineer.
Which construction tools are related?
Sibling for masonry mortar: mortar calculator. For adjacent tasks: masonry calculator for stone count, tile calculator for the bathroom finish after plastering, wall paint calculator for the paint layer as the next step, insulation calculator for the exterior thermal layer underneath the exterior plaster.
Specialty calculators for screed (floor instead of wall) and grouting mortar follow in phase B after evaluating first search-query data.
What questions do users ask most often?
The frontmatter of this page contains nine FAQ entries with schema.org/FAQPage markup, sourced from top Google ‘People Also Ask’ patterns for plaster topics. Answers address the question in the first ten words — voice-search-optimised for smart speakers and AI search assistants.
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