Mash Tun Capacity and Grain Bed Depth
Computes grain bed depth in a mash tun, the largest grain bill its depth limit allows.
Example
You enter
- Tun diameter (ft) 6
- Grain weight (lb) 542
- Mash thickness (qt per lb) 1.25
- Grain displacement (gal per lb) 0.08
- Maximum working bed depth (in) 18
- Batch volume (gal) 310
- Brewhouse efficiency (%) 78
- Extract potential (points per lb per gal) 37
- Wider tun to compare (ft) 8
You get
- Bed area (ft²) 28.2743
- Mash volume 212.7 gal (28.44 cu ft)
- Grain bed depth 12.1 in over 28.27 sq ft
- Most grain the tun will lauter 808 lb at 18 in
- Max og points 75.2507
- In the wider tun 6.7892
- Alternative max grain (lb) 1436.99
Checked against published worked examples from: John Palmer.
Details, formula, and sources
ScopeComputes grain bed depth in a mash tun, the largest grain bill its depth limit allows, and the strongest single-mash beer. The worked 6 ft tun holds 542 lb at 12.1 in and at most 808 lb at 18 in, which caps the brewhouse at 1.075. An 8 ft tun takes 78% more grain from a 33% wider vessel.
Formula or tablemash gal per lb = R/4 + displacement; depth = G x gal per lb / 7.48 / (pi D^2 / 4); max grain = area x depth limit x 7.48 / gal per lb.
Source and editionGeometry, with grain displacement about 0.08 gal per lb and 12 to 18 in the usual working bed depth. The lauter tun manufacturer's rated depth governs.
Free accessPublic geometry.
What governsEstimate. AHJ and licensed professional govern.
API field namestun_diameter_ft, grain_weight_lb, mash_thickness_qt_per_lb, grain_displacement_gal_per_lb, max_bed_depth_in, batch_volume_gal, efficiency_pct, extract_potential_ppg, alternative_diameter_ft, bed_area_sqft, mash_volume_gal, bed_depth_in, max_grain_lb, max_og_points, alternative_bed_depth_in, alternative_max_grain_lb
- Vessel a flat-bottomed cylinderspec-v1787