Dehydration Ratio Calculator & Dried Yield from Fresh
Dries tomato
“One accepted answer here saves a hundred people an hour each.
Find your dried yield and dehydration ratio — from fresh weight and moisture get the dried product, the fresh-to-dry ratio, the water removed and the yield %.
Enter your produce
Next: dry down to the safe storage moisture (10%) and pack the dried product airtight (sealed jars/pouches) away from light and humidity to stop it re-absorbing water and spoiling.
Dry matter is conserved; dried = fresh×(1−freshMoist)/(1−driedMoist).
Dehydration — key facts
- Dried weight
- fresh×(1−fM)/(1−dM)
- Tomato
- ~94% water (≈15:1)
- Chilli
- ~80% water (≈4.5:1)
- Leafy greens
- ~90% water
- Target dried
- ≈ 8–12%
- Conserved
- dry matter & nutrients
- Why dry
- preserve, store, add value
- Privacy
- Runs in your browser; nothing uploaded
Turn a glut into a stable, valuable product
Fresh produce is mostly water, so drying it shrinks the weight dramatically — and that dehydration ratio is the number you need to plan a drying enterprise. It tells you how much fresh material a target quantity of dried product requires, how much drier capacity and store space you'll need, and how to price the dried product to cover the huge weight loss.
This tool computes the dried weight, the fresh-to-dried ratio, the water removed and the yield % from your fresh weight and moistures, for tomatoes, chillies, onion, ginger, turmeric, raisins and more. Dry to a safe storage moisture (8–12%) at gentle temperatures to preserve quality, and store airtight. Pair it with the Crop Drying Time tool (for time and energy) and the Storage Loss tool to keep the dried product stable.
Plan the batch
Know the fresh input needed for a target dried output.
Size the drier
The ratio sets your drier capacity and store space.
Price it right
Dried product must cover the big weight loss.
Compare produce
See which crops shrink most and value-add best.
Frequently Asked Questions
What is the dehydration ratio?+
It's how many kilograms of fresh produce you need for one kilogram of dried product — for example, about 15:1 for tomatoes, meaning 15 kg of fresh tomato gives roughly 1 kg dried. It depends on the moisture removed: high-water produce has a big ratio. This tool computes it from your fresh and dried moisture.
How much dried product will I get from fresh?+
Dry matter is conserved, so dried weight = fresh × (1 − fresh moisture) ÷ (1 − dried moisture). 100 kg of fresh tomato at 94% moisture dried to 10% gives about 6.7 kg. Enter your weights and moistures and the tool gives the dried yield, ratio and water removed.
Why is the dried yield so small?+
Because most fresh produce is water — tomatoes are ~94% water, leafy greens ~90%, chillies ~80%. Drying removes nearly all of it, so only the small dry-matter fraction remains. That's why dehydration ratios are high and dried products are concentrated and valuable per kilogram.
What moisture should I dry produce to?+
Low enough to store safely without mould — typically 8–12% for most dried vegetables, fruits and spices (a little higher for some fruits like raisins at ~15%). The tool defaults each produce to a safe target; dry to that and store airtight to keep the product stable.
Does drying lose nutrients or just water?+
Mainly water — the valuable dry matter (sugars, fibre, minerals, much of the protein) is conserved and concentrated, which is why dried foods are calorie- and nutrient-dense per gram. Some heat-sensitive vitamins (like vitamin C) decline, so gentle, lower-temperature drying preserves quality best.
Which produce has the highest drying ratio?+
The wettest — leafy greens (~90% water) and tomatoes (~94%) have ratios around 10–16:1, while less-watery items like ginger or banana are lower. The tool shows the ratio for each produce so you can plan how much fresh material a target quantity of dried product needs.
How do I use the ratio to plan?+
Work backwards: if you want 100 kg of dried chilli at a 4.5:1 ratio, you need about 450 kg of fresh. The ratio also tells you the drier capacity, labour and store space you'll need, and helps price the dried product to cover the large weight loss.
Does this work for a solar or mechanical dryer?+
Yes — the yield depends only on the moisture removed, not the drying method, so the dried weight and ratio are the same whether you sun-dry, solar-dry or use a mechanical dehydrator. The method affects drying time and quality (use the Crop Drying Time tool for time and energy).
Why dry produce at all?+
Drying preserves a glut, cuts weight and volume for cheaper storage and transport, prevents spoilage of perishables, and adds value — dried tomatoes, chillies, raisins and spices sell for far more per kilogram than fresh. It turns a short-shelf-life crop into a stable, sellable product.
How accurate is the calculation?+
The mass balance (dried weight from moistures) is exact. The presets use typical fresh and target moistures; your actual produce may differ, so measure or adjust the moisture inputs for precision. Real drying also has small handling losses not captured here.
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