A marinade can turn plain meat into something worth remembering, but only if there is enough of it. Too little and half the meat sits dry, picking up flavour on one side and nothing on the other. Too much and you waste good oil, vinegar and spices, and the meat can turn mushy from sitting in acid for hours. This calculator removes the guesswork: enter the weight of your meat and its type, and it tells you the total marinade you need, split into oil, acid and the rest.
The rates are based on coverage, not on a fixed recipe. Chicken needs about 120 millilitres per kilogram, beef about 150, pork about 130, fish only 80, lamb about 140 and tofu about 100. Fish needs less because it is delicate and absorbs flavour fast, while beef needs more because it is dense and often cut thick. These are starting points for a coating marinade in a bag, not for a deep bath, so if you use a wide dish instead of a bag, add a little extra to reach the same coverage.
Here is a worked example. You have 1 kilogram of chicken. At 120 millilitres per kilogram you need 120 millilitres in total. The split is 55 percent oil, which is 66 millilitres, 25 percent acid, which is 30 millilitres, and 20 percent for soy sauce, water and seasoning, which is 24 millilitres. That is about 8 tablespoons in total, which is easy to measure even without a jug. Scale it the same way for any weight: double the meat, double every part.
The balance of oil, acid and seasoning matters as much as the total. Oil carries flavour and helps the meat brown in the pan, acid tenderises and brightens, and salt and seasoning do the real flavour work. Too much acid, especially lemon juice or vinegar left for many hours, can cook the surface of the meat and make it chalky. A good rule is to keep acid at about a quarter of the total and to limit marinating time: fish 30 minutes, chicken a few hours, beef overnight at most.
The container you choose changes how much marinade you need. A zip bag pressed flat around the meat uses far less than a bowl, because the liquid stays in contact with the surface instead of pooling underneath. Press the air out, seal the bag, and lay it flat in the fridge so the marinade spreads evenly. Turn it once halfway through, especially for thick pieces, so both sides spend time in the liquid. For large cuts, score the surface lightly so the marinade can reach a little deeper.
Food safety is not optional with marinades. Raw meat marinade is not a sauce, because it has touched raw meat and can carry bacteria. Either throw it away or boil it hard for at least 3 minutes before serving it, and never pour unboiled marinade over cooked meat. Keep marinating meat in the fridge, never on the counter, and do not reuse a marinade for a second batch. These rules cost nothing and remove the main risk of an otherwise simple technique.
Use this calculator as the base, then adjust to your taste. Add garlic, herbs, chilli or mustard to the seasoning share, swap lemon juice for vinegar, or use part soy sauce for salt and depth. Keep the total volume and the rough split the same, and your changes will stay balanced. Write down what worked, because the best marinade is the one you can repeat: the right amount, the right balance, and meat that comes out flavoured all the way through.