Set your target sand ratio
Sample mixes for comparison
| Use case | Total volume | Sand % | Remainder split | Notes |
|---|---|---|---|---|
| Raised bed refresh | 100 L | 20% | Soil 65% • Compost 35% • Perlite 0% | Good drainage without drying too fast. |
| Container vegetables | 20 L | 15% | Soil 55% • Compost 30% • Perlite 15% | Balanced fertility with extra aeration. |
| Cactus and succulents | 10 L | 45% | Soil 45% • Compost 15% • Perlite 40% | Very fast draining; water sparingly. |
Adjust based on plant needs, climate, and watering habits.
How the calculator works
1) Sand volume
SandVolume = TotalVolume × (SandPercent ÷ 100)
2) Remaining volume
RemainderVolume = TotalVolume − SandVolume
3) Split the remainder
SoilVolume = RemainderVolume × (SoilShare ÷ 100)
CompostVolume = RemainderVolume × (CompostShare ÷ 100)
PerliteVolume = RemainderVolume × (PerliteShare ÷ 100)
If SoilShare + CompostShare + PerliteShare is not 100, the calculator normalizes them so their proportions stay consistent.
Steps for accurate mixing
- Pick a total volume based on your project size.
- Choose a sand percent that matches drainage needs.
- Set the remainder shares for soil, compost, and perlite.
- Optional: enter your container size to see bucket counts.
- Click Calculate, then download CSV or PDF if needed.
Drainage targets by plant group
Sand percentage indicates how quickly water moves through a mix. For most beds, 10–25% sand supports steady moisture and limits compaction. For patio containers, 15–30% sand reduces waterlogging after frequent irrigation. For succulents and herbs, 35–55% sand lowers root‑rot risk. If your native soil is clayey, start at the lower end and increase gradually after observing drainage over two watering cycles closely.
Interpreting sand percent and particle size
Choose coarse, clean horticultural sand, not very fine sand. Coarse particles form stable pores that improve oxygen flow. Fine sand can pack tightly with high compost and slow percolation. Rinse dusty sand before use to reduce crusting. If drainage is slow, raise sand slightly or increase aeration share. If it dries too fast, lower sand or increase organic matter.
Planning batches and repeatability
Standardize batches when filling multiple planters or refreshing beds in stages. Enter a container size to convert volumes into repeatable scoops. For large beds, scale the total volume and keep the same percentages. Mix dry ingredients first, then moisten evenly. Record bucket counts so a second batch matches the first.
Example data for validating a batch
| Input | Value | Expected output |
|---|---|---|
| Total volume | 40 L | Sand 10.0 L at 25% |
| Remainder split | Soil 50% • Compost 30% • Perlite 20% | Soil 15.0 L • Compost 9.0 L • Perlite 6.0 L |
If your measured volumes follow these trends, your units and inputs are consistent.
Managing fertility and long‑term structure
Sand improves structure, but it adds no nutrients. Compost provides fertility and water holding, yet excess compost can shrink and compact as it decomposes. Balance compost with soil and optional aeration so the mix stays open. After deep watering, check settling, then top up and re‑mulch. If drainage changes, adjust sand by 5% steps and retest.
Frequently asked questions
1) What sand type should I use?
Use clean, coarse horticultural sand. Avoid very fine sand because it can pack tightly. Do not use beach sand unless thoroughly washed and confirmed low in salts.
2) Why does the tool normalize the remainder shares?
If soil, compost, and perlite do not total 100, normalization preserves their proportions while correcting the total. This keeps the non‑sand portion consistent without changing your intended balance.
3) Can I set sand to 0%?
Yes. The calculator allocates the full volume to the remainder components. For dense mixes, consider adding a small aeration share to keep oxygen moving through the root zone.
4) How do I choose a good sand percentage?
Start with 15–25% for beds and 15–30% for pots. Increase sand for wet‑sensitive plants or cool seasons. Decrease sand in hot climates where mixes dry quickly.
5) Does sand replace perlite or pumice?
Not fully. Sand adds weight and drainage stability, while perlite or pumice increases air space with less weight. Many mixes work best with moderate sand plus a smaller aeration share.
6) Why are container counts shown as decimals?
The calculator converts volume into containers, so decimals are normal. Round consistently across components to keep the final ratio accurate, especially for small batches.
7) Should I measure by weight instead of volume?
Volume is practical for most garden batches. Weight is useful for large, repeatable production when moisture is controlled. If you weigh, keep materials at similar moisture levels for consistent results.