CURDCRAFT

Rennet Dosage Calculator

Enter your milk volume and your rennet’s strength ratio to get a dose in milliliters, plus how much cool water to dilute it into so it disperses evenly through the vat.

Printed on the bottle — e.g. single strength is often 1:10,000 to 1:15,000.
Total diluted volume as a multiple of the dose. 20 means 1 part rennet to 19 parts cool water.

Rennet dose

Rennet dose
1 mL
Diluted total
20 mL
Water to add
19 mL

Getting the dose right matters more than it seems

Too little rennet and the curd sets slowly and weakly, giving you a soft, fragile mass that tears instead of cutting cleanly. Too much rennet and the set comes on fast and firm, but the finished cheese can taste bitter as it ages, since excess coagulant keeps breaking down proteins long after the curd is cut.

Because rennet potency is expressed differently by every brand and format — liquid, tablet, single or double strength — the safest habit is to convert whatever you're holding into the same simple 1:X ratio and let the arithmetic do the rest, rather than trusting a rule of thumb written for a different product.

Frequently Asked Questions

What does a rennet strength like "1:10,000" actually mean?

It means 1 part rennet will clot 10,000 parts milk under standard test conditions. A higher ratio (like 1:15,000) means a more concentrated rennet, so you need less of it for the same milk volume — always use the ratio printed on your specific bottle or box, since strength varies by brand and type.

Why dilute the rennet before adding it to the milk?

A tiny, undiluted dose of rennet dropped straight into a large vat of milk doesn't disperse evenly — it clots the milk it touches first and leaves the rest under-dosed. Diluting the measured dose into a larger volume of cool, non-chlorinated water lets you stir it through the whole batch evenly before it starts to set.

Does water temperature matter for the dilution?

Yes — use cool water, not warm or hot. Warm water can start activating the rennet before it's evenly distributed, and chlorinated tap water can inhibit it, so cool, dechlorinated (filtered or boiled-and-cooled) water is the standard choice.

My curd isn't setting firmly enough — is it always a rennet dosage problem?

Not always. A weak set can also come from milk that's ultra-pasteurized (which doesn't coagulate well at all), acidity that's too low or too high at renneting, or a vat temperature that's off. Dosage is the first thing to check, but rule out those other factors too if the problem persists across batches.

Educational estimate only. Always confirm the dose against your specific rennet's label instructions — potency varies by brand, animal/microbial/vegetable source, and storage age.