Calculator
Use Total Area for flat coverage, or Bead for sealing around pots, planters, and borders.
Example data
Sample scenarios to sanity-check your inputs.
| Use case | Method | Inputs | Estimated final putty | Pack plan |
|---|---|---|---|---|
| Sealing planter rims | Bead | Length 8 m, width 12 mm, depth 8 mm, waste 8% | ~1.33 kg (density 1.60) | 2 × 1 kg packs |
| Patch small pot cracks | Total area | Area 0.25 m², thickness 4 mm, waste 10% | ~1.76 kg (density 1.60) | 2 × 1 kg packs |
| Edge sealing a raised bed | Bead | Length 12 m, width 10 mm, depth 6 mm, waste 12% | ~1.29 kg (density 1.60) | 3 × 0.5 kg packs |
Formula used
-
Total area method
Volume(m³) = Area(m²) × Thickness(m)
Volume(L) = Volume(m³) × 1000 -
Bead method
Volume(m³) = Length(m) × Width(m) × Depth(m)
Convert width and depth from mm/cm/in into meters. -
Mass and waste
Mass(kg) = Volume(L) × Density(kg/L)
Final(kg) = Mass × (1 + Waste%/100) -
Packs needed
Packs = ceil(Final(kg) / PackSize(kg))
How to use this calculator
- Choose a method: Total area or Bead.
- Enter measurements using any supported unit selector.
- Set density if your product label provides it.
- Add a waste factor for realistic ordering.
- Enter pack size and optional unit cost for budgeting.
- Press Calculate to view results above the form.
Coverage inputs and measurement approach
Accurate quantities begin with consistent measurements. For flat repairs, enter total surface area in square meters after subtracting openings, pots, or fixtures. A quick check is to multiply length by width for rectangles and use half-length times half-width times π for circular patches. Group small repairs into one summed area to reduce rounding errors. When dimensions are in centimeters or millimeters, always convert to meters before entry to keep the volume calculation correct and comparable.
Thickness and bead profile assumptions
Thickness drives volume. Garden putty is often applied as a thin skim (2–3 mm) for surface smoothing, while crack filling may need 4–6 mm. For joints, the bead method estimates a rectangular profile using bead width and depth; if the joint is concave, reduce the entered depth by about 20% to reflect the curved finish.
Density selection and product variability
Putty density varies by formulation. Lightweight acrylic or filler blends can be near 1.20 g/cm³, while cementitious or high-mineral products may be closer to 1.70 g/cm³. If the label shows coverage per kilogram, you can back-calculate an effective density by comparing the stated coverage with your intended thickness and then use that value for repeat jobs.
Waste allowance and practical site loss
Add waste to match real work conditions. Mixing loss, tool loading, edge trimming, and touch-ups commonly add 5–12%. Windy or hot days can increase waste if material skins over quickly. For first-time users or complex shapes, consider 15% and adjust after observing one test batch and its yield.
Packaging, budgeting, and purchase planning
Pack size affects both cost and leftovers. The calculator rounds up to whole packs, so smaller packs reduce overbuying on small jobs, while larger packs minimize unit price on big repairs. If unit cost is entered, you can compare scenarios—for example, two 1 kg packs versus one 2.5 kg pack—and pick the best balance of budget, storage, and shelf life.
FAQs
1) How do I measure irregular garden patches?
Break the shape into rectangles and circles, estimate each area, then sum them. For tiny repairs, measure a representative patch, multiply by the number of similar spots, and add a small waste factor.
2) What density value should I use if I’m unsure?
Start with 1.60 g/cm³, then adjust if your product label indicates a notably lighter or heavier formulation. After one job, compare ordered mass to actual use and refine the density for future estimates.
3) Should I use the area method or the bead method?
Use area for flat skim coats and patching. Use bead for sealing joints, edges, or grooves where width and depth are easier to measure than surface area.
4) Does the estimate include primer, paint, or sealant?
No. The calculator estimates putty mass only. Primers, paints, and sealants have different coverage and should be planned separately using their label rates and the same measured area.
5) Why does the calculator round up pack quantities?
Materials are purchased in whole packs, so the result rounds up to ensure you have enough product after waste and on-site variation. If the rounded quantity feels high, try a smaller pack size for finer ordering.
6) How do I download CSV or PDF results?
After calculating, use the CSV or PDF buttons in the results panel. The export captures your inputs, key assumptions, totals, and pack count, making it easy to share with a supplier or keep job records.