Say when?
Over- or under-pitching might result in slow starts, flavour issues, not to mention high costs, so it's important to get right.
This calculator will allow you to estimate your pitch rate in cells/mL from either dry grams/HL or total grams. That 'cells/mL' number will allow you to re-pitch accurately.
A commonly given ball park for ale is 5-10 million cells/mL of wort, but dry yeasts tend to specify a much lower range of 1-5mn cells/mL. For both Safale S-04 and US-05, Fermentis advise a range of between 50 and 80 grams per hectolitre. That translates to rates of between 3mn & 4.8mn cells/ml. Quite a wide margin. At the lower end, we expect more esters, rather than a cleaner product at the high end. For re-pitching cropped yeast, you might choose to increase the pitch (all other things being equal) to compensate for lesser vitality.
The calculations provided here are estimates only, because the manufacturer's specified cell count is taken at the point of manufacture. In reality, age, storage and pitching technique will affect the viability achieved in the brewhouse. If you want to know exactly how much you're pitching, you've got to get the microscope out, but in the meantime I hope this is helpful.
Brewhouse
Pitch
Calculate pitch rate in cells/mL and grams/HL from the total dry cell weight to be pitched.
| Total pitch (dry weight): | g |
| Pitch rate (dry weight): | g/HL |
| Pitch rate (cells): | x106 (million) cells/mL |
Calculate pitch rate in grams/HL and total dry cell weight to pitch from pitch rate in cells/mL.
| Pitch rate (cells): | x106 (million) cells/mL |
| Total pitch (dry weight): | g |
| Pitch rate (dry weight): | g/HL |
Calculate pitch rate in cell/mL and total dry cell weight to pitch from pitch rate in dry grams/mL.
| Pitch rate (dry weight): | g/HL |
| Total pitch (dry weight): | g |
| Pitch rate (cells): | x106 (million) cells/mL |
Each supplier provides technical data, including rehydration instructions, recommended pitch rate, preferred temperature range & the minimum viable cell count per gram, (as used above).
Lallemand (Gravity → Total Dry Weight)
Lallemand technical data sheets
Fermentis SafAle/Lager technical data sheets
Fresh dry yeast costs***
| Dry yeast cost (batch): | GBP |
| Cost (month~): | GBP |
| Cost (annum): | GBP |
Re-pitch savings
| Annual savings (5x re-pitch): | GBP |
| Annual savings (10x re-pitch): | GBP |
* Data sources for pricing and min. viable cell counts, (correct as at 19th December 2018):
Fermentis, Lallemand Murphy & Son, Get Er Brewed
** Particular attention must be paid to the minimum viable cell count specified by the manufacturer because this is a key component of the calculations and varies widely. For example, US-05 provides 6 billion cells/gram compared to just 1bn cells/g in Lallemand New England yeast. Check out the packaging or manufacturer technical data sheet for the number.
*** based on 500g pack pricing