Engineering · Finance · Planning

Practical Calculators Built for Exact Decisions

Free, instant engineering and finance estimators with stated formulas, transparent assumptions, and zero tracking. Pure client-side computation — loads in milliseconds.

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Showing 9 categories (30 calculators)

Zero Latency Client Engine — Instant computation, zero network roundtrips, works completely offline.

Verifiable Technical Formulas — Stated assumptions grounded in NEC, Darcy-Weisbach, NEMA, and USGS standards.

Private & Autonomous — Zero trackers, no required accounts, no tracking cookies, and no paywalls.

What these calculators help you decide

Decivia turns practical inputs into transparent estimates: wire size from current and distance, pipe loss from flow and diameter, material quantities from area and depth, tank volume from dimensions, drivetrain speed from gearing, and household costs from user-entered rates.

Every calculator shows its formula, a worked example, assumptions, and limitations. Results are estimates for planning and comparison, not certified engineering designs, code determinations, or professional financial advice.

Electrical Sizing

Wire gauge, ampacity rating, voltage drop percentage, and transformer VA sizing for commercial or residential circuits.

Wire size & ampacity calculator Voltage drop calculator Transformer VA sizing calculator All electrical tools & charts

Pipe Flow & Hydraulics

Flow velocity and Darcy-Weisbach pressure drop calculations across PVC, copper, steel, and HDPE pipe materials.

Pipe pressure drop calculator Pipe flow rate & velocity Differential pressure calculator All pipe tools & flow reference

Gear Ratio & Drivetrain

Wheel RPM, road speed, and torque multiplication from engine RPM, transmission ratios, and tire circumference.

Gear ratio & speed calculator Final drive ratio & axle torque Spring-rate calculator All mechanical & drivetrain tools

Construction Materials

Area, volume, and waste-adjusted quantities for flooring, drywall sheets, gravel, and deck boards.

Room area & flooring calculator Deck material & board count Drywall sheet count & area Gravel & topsoil volume Combined project materials Construction cost estimator Ramp slope planner Baluster spacing planner All construction estimators

Tank Capacity & Fill

Total capacity and partial-fill liquid volume exploration for rectangular and horizontal cylindrical tanks.

Tank volume & fill calculator Liquid fill level & dipstick Fuel tank capacity estimator All tank calculators

Engineering Reference Tables

Reference tables for lumber beam/joist spans and USGS water hardness classification with unit conversion.

Beam & joist span lookup Water hardness classification Reference tables directory Charging-time calculator All engineering reference lookups

Statistics

Build relative frequency tables from category counts, including percentages and cumulative totals.

Relative frequency table calculator All statistics tools

Finance & Annuity

Present-value annuity factors for ordinary annuities and annuities-due across custom rates and periods.

Present-value annuity calculator All financial planning tools

Household Cost Planning

Estimate monthly utility allocations, projected car lease overage mileage costs, and service rates.

Monthly utility cost estimator Lease mileage overage estimator Pet-sitting & boarding cost Combined cost planner All household cost calculators