Mushroom Agar Recipe Calculator
Scale any agar recipe to the exact number of Petri dishes you plan to pour — with real-world overage, firmness and sterilization built in.
Your recipe
| Ingredient | Amount |
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- Keep any flask or bottle no more than ¾ full to avoid boil-over in the pressure cooker.
- Cool to ~50 °C (comfortable to hold), then pour in still air or a flow hood to reduce contamination.
Overview
The Mushroom Agar Recipe Calculator turns a batch target — "I want to pour 10 plates" — into a precise ingredient list for the exact volume of nutrient agar you need. It works from the concentrations professional and hobby cultivators actually use, then adjusts for the real losses that theoretical recipes ignore: media left behind in the flask, evaporation during pressure sterilization, and the difference between firm and soft plates.
It is built for home cultivators, spawn producers, lab technicians, and mycology students who clone mushrooms, isolate cultures from spores, or store strains on slants. Whether you use Malt Extract Agar, Potato Dextrose Agar, or your own blend, the tool removes the guesswork so you mix the right amount once — no half-empty plates and no wasted media.
How it works
- Pick your recipe. Choose MEA, LME, PDA, Honey Agar, or Custom. Each recipe carries its own nutrient concentrations per litre.
- Set the batch. Enter how many Petri dishes you want and select their diameter — the calculator knows the practical pour volume for each size.
- Tune the details. Adjust the overage allowance (extra media for waste) and agar firmness to match how you like your plates.
- Calculate. Click Calculate recipe to get water, agar, and every nutrient weighed to the gram, plus sterilization guidance.
- Reset any time. Click Reset to clear the results and start a new batch.
Formula explanation
Everything scales from one figure: the total media volume you actually need to pour your batch.
Total media (mL) = Plates × Volume-per-plate × (1 + Overage%)
That volume is converted to litres, and every ingredient is a rate per litre:
Agar (g) = Firmness% × 10 × LitresNutrient (g) = Rate-per-litre × LitresWater (mL) ≈ Total media volume
For example, a 2.0% firmness works out to 20 g of agar per litre, and MEA adds 20 g of malt extract per litre. Solids are dissolved into water that is measured to the target volume — the standard "make up to volume" method used in every microbiology lab.
Practical benefits
- No wasted media. Mix the exact amount for your plate count instead of eyeballing and tossing the leftovers.
- Consistent plates. Fixed firmness and pour volume mean every dish sets the same way, batch after batch.
- Fewer failed pours. Built-in overage covers flask residue and evaporation, so you don't come up two plates short.
- Repeatable results. Save your settings as a house recipe and hand it to anyone on your team.
- Cost control. Buying malt extract or dextrose in bulk becomes predictable when you know your true per-batch usage.
Frequently asked questions
It depends on dish size. A standard 90 mm dish holds a practical pour of about 18 mL, a 100 mm dish about 20 mL, and a large 150 mm dish around 45 mL. This calculator uses those working volumes rather than the theoretical minimum, so your plates are deep enough to resist drying out.
You never recover 100% of what you mix. Some media clings to the flask, and a little water boils off during pressure sterilization. A 10% overage covers those losses so you don't run out mid-pour. Increase it for very small batches or long sterilization cycles; lower it if you pour efficiently from a graduated bottle.
2.0% w/v (20 g of agar per litre) is the reliable default — firm enough to handle, flip, and store without tearing. Drop toward 1.5% for softer plates that are easier to cut for transfers, or push to 2.5% for slants and long-term storage where you want extra rigidity.
Mix all ingredients into the water first, then sterilize the complete liquid media in a pressure cooker or autoclave at 15 PSI (121 °C). The calculator gives a hold time based on your batch volume. After sterilizing, let it cool to around 50 °C before pouring so the plates don't collect condensation.
