Fertilizer Dilution Calculator
Ratio
1:3
Concentrate %
25.0%
How it works
Liquid fertilizers and concentrated solutions must be diluted to the correct application rate to avoid burning plants or under-feeding them. The Fertilizer Dilution Calculator converts concentrate-to-water ratios into precise volumes for any tank or container size.
**N-P-K explained** Fertilizer labels show three numbers: Nitrogen (N), Phosphorus (P), Potassium (K) percentages by weight. A 10-10-10 fertilizer is 10% N, 10% P, 10% K. Nitrogen drives leafy growth; phosphorus supports root development and flowering; potassium supports overall plant health and disease resistance.
**Application rates** Typical liquid fertilizer dilution ratios: 1:50 (1 part concentrate per 50 parts water) for weekly feeding, 1:100 for frequent feeding, 1:200 for seedlings or sensitive plants. For 10 liters at 1:100, use 100 ml concentrate plus 9.9 liters water.
**Fertilizer burn** Over-concentration draws water out of plant roots via osmosis, causing wilting and leaf tip burn even when soil is moist. Flush soil with clean water after accidental over-application.
**Hydroponic applications** Hydroponic nutrients require precise dilution, measured in EC (electrical conductivity). Target EC ranges by crop: lettuce 1.0 to 2.0 mS/cm, tomatoes 2.0 to 4.0 mS/cm, herbs 1.6 to 2.2 mS/cm.
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Frequently Asked Questions
- Dilution ratio specifies how much concentrate to mix with water. Common formats: '1:50' means 1 part concentrate per 50 parts water — to make 1 liter of solution, use 1/51 liter (about 20ml) concentrate plus 50/51 liter water. '10ml per liter' means add 10ml to 1 liter of water. Percent concentration means grams of fertilizer per 100ml water — '0.1% solution' = 1g per liter. Always check which format your product uses; mixing up the format can produce a solution 5–10x too concentrated. For foliar feeding (spraying on leaves): use the most dilute (weakest) recommended rate — leaves absorb fertilizer more readily than roots and burn more easily.
- Some combinations are compatible; others precipitate (form solids) or release harmful gases. Safe to mix: most NPK liquids with chelated micronutrient solutions. Incompatible: calcium-based fertilizers with phosphate or sulfate fertilizers — they form calcium phosphate or calcium sulfate precipitate. Also incompatible: concentrated hydrogen peroxide with most fertilizers. If you're unsure: add each product to the tank separately in water, mixing and checking between additions. Never pre-mix concentrates before adding to water. If a mixture turns cloudy or forms solids, it has precipitated — those nutrients are no longer available to plants. When in doubt, apply products in separate tank mixes.
- Over-fertilization (nutrient toxicity or fertilizer burn): leaf tip burn (brown, crispy tips), wilting despite moist soil, white salt crust on soil surface. Correct by flushing soil thoroughly with clean water (2–3 times the pot volume) and withholding fertilizer until plants recover. Under-fertilization (deficiency): yellowing (nitrogen deficiency starts with lower/older leaves), purple tinges (phosphorus deficiency in cool weather), marginal yellowing with green veins (potassium), interveinal yellowing on new growth (iron or manganese, common in alkaline soil). Address deficiencies by correcting fertilizer rate and, for micronutrient deficiencies, correcting soil pH before increasing micronutrient application.
- Container plants: fertilize more frequently because watering leaches nutrients rapidly. Liquid fertilizer every 1–2 weeks during the growing season; slow-release granular fertilizer every 2–3 months. Reduce or stop in winter when growth slows. In-ground plants: fertilize less frequently — soil biology and organic matter buffer nutrient availability. For vegetables: at planting (balanced NPK), then side-dress with nitrogen when plants are half their mature size, then again when fruiting starts. For lawns: 4 times per year maximum for cool-season grasses. Over-fertilizing in-ground garden beds is a more common mistake than under-fertilizing — excess nitrogen causes lush foliage at the expense of fruit production.