Just finished putting together PlumberCalc.com with 22 different calculators I've been working on. Got tired of bouncing between different apps and websites every time I needed to do basic plumbing calculations. Covers the stuff I find myself calculating regularly: Pipe sizing and flow calculations - get the right pipe diameter fast Pressure loss calculations - figure out system pressure drops Drain and vent sizing - proper drainage system design Water heater and expansion tank sizing - residential and commercial Pump sizing and selection - match pumps to system requirements Hydraulic calculations - flow rates, velocities, head loss Main thing - everything works instantly on your phone. No app downloads, no registration, loads fast even with crappy cell service on job sites. Just bookmark it and use whatever you need. Built it because I was spending too much time hunting for the right formula or trying to remember if I already did a calculation. Wanted something that just works when you need it. Made it all free with no ads. Don't collect any data either - just straight-up tools for getting work done.