Lentil Cook Calculator
Dry lentils to cooked yield, water, and serving count.
What it does
Lentils triple near enough in the pot, which makes dry weights hard to picture as meals. A small bag turns into a wide pot of stew, and a cup too many floods the week with leftovers. Weight math fixes the plan.
The tool above multiplies dry weight by 2.6 for cooked yield and by 2 for water, then divides into 100 g servings. Metric mode uses grams and milliliters; imperial mode uses ounces and fluid ounces. Both follow the same ratios.
Those ratios sit on USDA food data and extension cooking guides: a cup of dry brown near 190 g cooks to roughly 500 g. Brown and green hold shape; red splits soften into puree at similar weights. Age, water hardness, and salt timing nudge the finish.
Cook from the numbers, then trust the bite. Start checking whole lentils near 20 minutes and red near 12. When they crush softly with no chalky core, drain, season, and portion. Leftovers chill fast and reheat well with a splash of water.
How to use
- Pick metric (grams) or imperial (ounces).
- Weigh dry lentils after rinsing and picking over.
- Enter the weight and read cooked yield.
- Measure water: twice the dry weight.
- Simmer whole lentils 20 to 30 minutes, red 12 to 18.
- Drain any surplus and portion by servings.
Formula
- dry
- Dry lentil weight in grams or ounces.
- 2.6
- Dry to cooked weight factor.
- serving
- Cooked serving: 100 g or 3.5 oz.
Water is by weight: 1 g dry needs 2 ml water; 1 oz dry needs 2 fl oz water. Servings use 100 g (3.5 oz) cooked. Very old lentils absorb slower, so keep extra hot water ready rather than flooding at the start.
Worked example
Example: 300 g dry lentils
300 g dry brown lentils, simmered until tender.
- Dry weight is 300 g brown lentils.
- Cooked: 300 x 2.6 = 780 g.
- Water: 300 x 2 = 600 ml.
- Servings: 780 / 100 = 7.8.
- Plan: about 8 half cup servings from one pot.
Reference table
| Type | Time | Holds shape |
|---|---|---|
| Brown | 20 to 25 min | Yes, salads and sides |
| Green | 22 to 30 min | Yes, firm bite |
| French green | 25 to 30 min | Very firm |
| Red split | 12 to 18 min | No, melts soft |
| Black beluga | 22 to 28 min | Yes, small firm |
Limits
- Average for common brown and green. Red splits and French green vary.
- No soak model; old stock cooks slower.
- Seasoning, oil, and veg add weight outside this math.
- Altitude and hard water shift minutes, not ratios much.
Common mistakes
- Eyeballing dry cups instead of weighing.
- Flooding the pot, then pouring flavor away.
- Salting heavily at the start with hard water.
- Walking away during the last five minutes.
- Storing warm pots deep in the fridge.
Try it yourself
Quick checks. Answers sit tucked under each question.
Yield from 500 g dry?
Cooked is 500 x 2.6 = 1,300 g. Water is 1,000 ml. Servings are 13.
Yield from 17.6 oz dry?
Cooked is 17.6 x 2.6 = 45.8 oz. Water is 35.2 fl oz. Servings are 13.1.
Questions
How much do lentils expand when cooked?
About 2.5 to 2.7 times the dry weight for brown and green; red splits land a bit lower because they break down. The tool uses 2.6 as a middle value. Salt late and drain well for exact weights.
Do lentils need soaking like beans?
Rinse, cover with about twice their weight in water, simmer 20 to 30 minutes for whole types and 12 to 18 for red. No presoak needed. Start tasting early; mush arrives fast.
How many cups cooked per cup dry?
Yes. One cup of dry brown (about 190 g) gives about 2.5 to 3 cups cooked. One cup dry red (about 200 g) gives a thick puree that measures less but weighs similar.
Do red and brown lentils cook the same?
Brown and green hold shape for salads; red splits melt into soups and dals. French green takes a few minutes longer and stays firm. Times shift with age and storage.
How do I store leftover lentils?
Chill within two hours, refrigerate up to 4 days, or freeze flat in portions. Reheat with a splash of water since starch firms in the cold.
Why are my lentils still hard?
Underseasoned pots and hard water slow softening. Acid from tomatoes or vinegar added early can keep skins firm, so add it after the lentils turn tender.
Sources
- USDA FoodData Central: lentils
- FDA: produce and legume food safety
- Iowa State Extension: cooking dry beans and lentils