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Calcimator

Yogurt Culturing Calculator

Calculate culture amount, incubation time, and temperature for homemade yogurt. Supports mesophilic and thermophilic cultures with thickness options.

About this calculator

Homemade yogurt needs a starter culture stirred into warm milk at roughly 2.5% of the milk's volume, and this calculator scales that amount directly from Milk Volume -- it's the only input that changes Culture Amount, since neither Culture Type nor Target Thickness enters that part of the formula. Culture Type is what determines Target Temperature: a Mesophilic culture ferments at cooler room temperature (75°F) over about 12 hours, while a Thermophilic culture needs active warmth (110°F) and works faster, at about 8 hours -- Milk Volume and Target Thickness have no effect on which temperature the milk needs to be held at.

Target Thickness then scales the base incubation time from that culture type: Thin (drinkable) yogurt uses 80% of the base time, Medium (spoonable) uses the base time as-is, and Thick (Greek-style) extends it to 120% of the base time, reflecting that a longer, more complete fermentation produces a firmer set before straining. Greek-style yogurt also has a substantially lower Estimated Yield than the other two thickness levels, because straining away the liquid whey to thicken it removes volume the other styles keep.

Inputs

Results

Culture Amount

25 mL

Incubation Time8 hrs
Target Temperature110 °F
Target Temperature43 °C
Estimated Yield950 mL
How to Use This Calculator
  1. Enter milk volume in mL.
  2. Select culture type: mesophilic (room temperature, 12 hrs) or thermophilic (110 °F, 8 hrs).
  3. Choose target thickness (thin drinkable, medium spoonable, or thick Greek-style).
  4. The calculator shows culture amount in mL, incubation time, target temperature in °F and °C, and estimated yield.
  5. For a thermophilic culture, first heat the milk to 180 °F and hold 10 minutes, then cool it DOWN to the target temperature before stirring in the culture; incubate undisturbed at that temperature for the full indicated time.

How the result changes with Milk Volume (mL)

Milk Volume (mL)Culture Amount
50013 mL
75019 mL
1,50038 mL
2,50063 mL

What each input means

Milk Volume (mL)
Volume of milk in milliliters. 1 liter = 1000 mL.
Culture Type
Mesophilic cultures at room temp. Thermophilic needs a warm environment (110°F).
Target Thickness
Thicker yogurt requires longer incubation. Greek-style involves straining whey.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Milk Volume (mL) = 1000, Culture Type = 2, Target Thickness = 2 = 3 input(s) provided
  2. Calculate Culture Amount
    Culture Amount
    25 = 25
  3. Calculate Incubation Time
    Incubation Time
    8 = 8
  4. Calculate Target Temperature
    Target Temperature
    110 = 110

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Does the culture type change how much starter culture I need?

No. Culture Amount is calculated purely from Milk Volume at a fixed roughly-2.5% ratio -- it does not change between Mesophilic and Thermophilic cultures, or with your chosen Target Thickness. Culture Type instead determines the incubation temperature and base incubation time.

Why does Greek-style yogurt have a lower estimated yield?

Greek-style (Thick) yogurt is strained to remove liquid whey, which is what gives it its dense, spoonable texture -- but that straining also removes volume. This calculator estimates Greek-style yield at about 60% of the starting milk volume, versus about 95% for Thin and Medium thickness, which aren't strained.

What's the difference between mesophilic and thermophilic cultures?

Mesophilic cultures ferment at room temperature (around 75°F) over roughly 12 hours and don't require an external heat source. Thermophilic cultures need to be held at a warmer 110°F and typically finish faster, in about 8 hours -- most common store-bought yogurt is made with thermophilic cultures.

Does milk volume affect the incubation time or temperature?

No. Incubation Time is set by Culture Type and Target Thickness only, and Target Temperature is set by Culture Type alone. Milk Volume only affects Culture Amount and Estimated Yield, which both scale directly with how much milk you're culturing.

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