Plumbing Calculators — Construction
Drainage and ventilation sizing: pipe size, drain slope, rain gutter sizing, and bathroom extraction fans. Drain slope has a workable range rather than a minimum, since too steep also causes problems.
All Plumbing Calculators
Calculate the CFM rating needed for a bathroom exhaust fan from room volume.
Calculate the required slope for drain pipes using code-minimum grade per foot.
Calculate pipe size with inputs, formulas, and instant results.
Calculate gutter size and downspout spacing from roof area and local rainfall intensity.
Determine septic tank size requirements from bedroom count and daily wastewater flow.
Calculate the right sump pump size from pit dimensions, water inflow rate, and head height.
Size a tankless water heater from peak flow rate and temperature rise requirements.
Determine water main pipe size from fixture count, demand, and street pressure.
Calculate water pressure with inputs, formulas, and instant results.
Calculate salt usage and refill frequency for water softeners from hardness and household size.
Size water supply pipes based on fixture count and flow demand using code tables.
Find your correct bra size
International clothing and shoe sizes
About Plumbing Calculators
Drainage and ventilation sizing: pipe size, drain slope, rain gutter sizing, and bathroom extraction fans. Drain slope has a workable range rather than a minimum, since too steep also causes problems.
Whether you need to solve a one-time problem or verify your own calculations, these free tools cover the most common plumbing scenarios. All results are computed in your browser — no data is sent to any server.
What You Can Calculate
This section includes 13 tools: Bathroom Ventilation Fan Calculator, Drain Pipe Slope Calculator, Pipe Size Calculator, Rain Gutter Size Calculator, Septic Tank Size Calculator, Sump Pump Size Calculator, Tankless Water Heater Size Calculator, Water Main Size Calculator, and 5 more. Each calculator is free to use with no signup required.