Transformer sizing, motor current, cable sizing, DG sets, pump calculations, and financial planning tools — every formula shown, every result accurate to the standard your job demands.
Find the correct kVA rating for a transformer based on your connected load and voltage.
kVA = (V × I × √3) / 1000Convert between apparent power and real power using your system's power factor.
kW = kVA × PFConvert horsepower to kilowatts and back — built for motor nameplate conversions.
kW = HP × 0.7457Estimate full-load amperage for single or three-phase motors from rated power and voltage.
I = P / (V × √3 × PF)Size the correct capacitor bank to correct your system's power factor.
kVAR = kW × (tanφ1 − tanφ2)Convert kVA to line current and back for single or three-phase systems.
I = kVA × 1000 / (V × √3)Convert real power directly to current draw using voltage and power factor.
I = kW × 1000 / (V × √3 × PF)Determine the right diesel generator rating for your connected and starting load.
kVA = Total Load / PF 🔥 PopularSelect the correct conductor size based on current, length, and voltage drop limits.
A = (ρ × L × I) / VdFind the right inverter VA rating for your load, with surge and safety margin included.
VA = Watts / PFEstimate battery backup runtime, or find the battery Ah needed for a target backup time.
Runtime = (Ah × V × η) / WFind the right UPS kVA rating and input current for your load and power factor.
kVA = Load (kW) / PFOur complete suite — cable sizing, voltage drop, fault current, and load balancing in one tool.
All-in-one toolkitEstimate L10 bearing service life from dynamic load rating and operating speed.
L10 = (C/P)^pCalculate gear ratio, output speed, and torque multiplication for a gear pair.
GR = T2 / T1Estimate total head a pump must overcome including elevation and friction loss.
H = Hs + Hf + HvCalculate Total Dynamic Head for correct pump selection in your system.
TDH = Static + Friction + Pressure HeadCalculate cooling tower efficiency for correct cooling tower selection in your system.
Efficiency (%) = Range ÷ (Range + Approach) × 100Calculate belt length for correct belt in your system.
Belt Length = 2C + 1.57 × (D2 + D1) + (D2 − D1)² ÷ (4 × C) Where: C = Center distance between pulleys D1 = Driver (smaller) pulley diameter D2 = Driven (larger) pulley diameterFinancial planning tools for engineers and technicians — plan your retirement corpus, investments, and growth rate alongside your day-to-day engineering calculations.
Project your EPF retirement corpus with an annual salary step-up percentage, using the same monthly interest method EPFO applies to your passbook.
Interest = Opening Balance × (Rate ÷ 12) 🔥 PopularCalculate SIP maturity with annual step-up, or compare against a one-time lump sum investment, using the standard formula used by major fund houses.
FV = P × [(1+r)^n − 1] / r × (1+r)Find the annualized growth rate of any investment between a starting and ending value.
CAGR = (FV/PV)^(1/n) − 1Estimate your gratuity payout.
Gratuity = (15 × Salary × Years) ÷ 26, Capped at ₹20,00,000Compare your tax liability under the Old vs New regime and pick the option that saves you more.
Tax = Σ (Slab Income × Slab Rate)Calculate the maturity value of your fixed deposit with quarterly compounding.
A = P × (1 + r/n)^(n×t)Find the maturity value of your recurring deposit based on monthly installment and tenure.
M = P × [(1+r)^n − 1] / (1 − (1+r)^(-1/3))Project your Public Provident Fund maturity value over the 15-year lock-in with annual contributions.
A = P × [(1+r)^n − 1] / r × (1+r)Estimate your NPS pension corpus at retirement and the monthly annuity it can generate.
Corpus = Σ Contributions × (1+r)^nEvery calculator displays the exact formula used, so you can verify or learn it.
Default constants follow common industry standards, not arbitrary rounding.
Fast on mobile data, no login walls — get your number in seconds on site.
Every calculator on this site is free, with no usage limits or paywalls.
Saved me a trip back to the office just to size a DG set. Formula's right there, result checks out every time.
Cable size and voltage drop calculators are spot on with IS standards. Use it for every panel drawing now.
Mechanical Engineer — the formula chips actually helped me understand the concept, not just get an answer.
Downloadable AMC trackers, maintenance checklists, and ready-made engineering spreadsheets — built to save hours on repetitive paperwork.
kVA (kilovolt-amperes) is apparent power — the total power flowing in an AC circuit, including both the power doing useful work and the power lost to reactive loads like motor coils. kW (kilowatts) is real power, the portion that actually performs work. The two are related by power factor: kW = kVA × PF. A power factor of 1.0 means all apparent power is real power; most industrial loads run between 0.8 and 0.95.
Power factor determines how much of the delivered apparent power (kVA) is actually converted into usable work (kW). A low power factor means transformers, generators, and cables must be rated larger to deliver the same real power, raising equipment cost and line losses. Many utilities also penalize industrial customers for poor power factor, which is why correction capacitors (APFC panels) are common on factory floors.
Add up your total connected load in kW, divide by the expected power factor to get kVA, then add a safety margin — typically 20–25% — for future load growth and motor starting surges. Our Transformer Size and DG Size calculators handle this automatically and round up to the nearest standard rating.
Yes — every formula used is the same standard formula taught in electrical and mechanical engineering coursework and referenced in field handbooks. That said, for safety-critical or code-compliance decisions, always verify results against your local electrical code and have them reviewed by a licensed engineer. The EPF, SIP, and CAGR calculators follow the standard methods used by EPFO and major mutual fund houses, and are for educational planning purposes only — they do not constitute financial advice.
Almost every electrical, mechanical, or financial calculation you'll ever need on the job or in coursework comes down to a handful of well-established formulas. The hard part usually isn't the math itself — it's remembering the right constant, tracking down the correct standard, or doing the arithmetic quickly enough to keep moving. ElectroMechCalc was built to remove that friction. Every calculator on this site — whether it's sizing a transformer, converting kVA to kW, estimating a motor's full-load current, or projecting an EPF maturity value — shows the underlying formula alongside the result, so the number you get is something you can verify, learn from, and trust, not a black box you have to take on faith.
The site is organized into three broad categories: electrical calculators, mechanical calculators, and financial planning calculators. The electrical section covers the calculations that come up most often around panels, transformers, and motors — transformer kVA sizing, kVA-to-kW and kW-to-current conversions, motor full-load current, APFC capacitor sizing for power factor correction, cable sizing, diesel generator sizing, inverter and UPS sizing, and solar panel array sizing. The mechanical section handles the calculations technicians and maintenance engineers reach for on rotating equipment and fluid systems — bearing L10 life, gear ratios, pump head and total dynamic head, belt length, and cooling tower efficiency. The financial section applies the same formula-first philosophy to personal finance — EPF, gratuity, SIP and lump-sum investment growth, CAGR, income tax comparison between the old and new regimes, fixed and recurring deposits, PPF, and NPS. Different domains, same principle: show the math, use standard-aligned defaults, and give an answer fast enough to be useful in the middle of a task.
Most visitors fall into one of a few groups. Electrical and mechanical engineering students use the calculators to check homework and lab results against a known-good formula rather than trusting a single worked example from a textbook. Site electricians and technicians use them standing in front of a panel or a pump skid, where a fast, mobile-friendly calculator beats flipping through a handbook or hunting for a signal to load a heavier tool. Plant maintenance teams use the bearing life, pump head, and cooling tower calculators to plan replacements and diagnose underperforming equipment before it fails outright. Facility managers use the transformer, DG, UPS, and solar sizing calculators when planning capacity for a new load, an expansion, or a backup power system. And because a lot of that same audience also plans their own retirement and investments, we added a small, focused set of financial calculators — EPF, SIP, CAGR, and the rest — built with the same emphasis on transparent, checkable math.
Every calculator follows the same basic pattern. You enter the inputs the formula actually needs — nothing extra, no forced sign-up, no account. The result appears instantly in the browser, along with the formula that produced it and a short explanation of what each term means. If a calculator involves an industry-standard constant or default assumption — a typical power factor, a standard safety margin, a common motor efficiency — that default is disclosed rather than buried, and in most cases you can override it if your specific situation calls for something different. Because the page shows its work, you can sanity-check the result by hand if you want to, use it to double-check a manual calculation, or use it to learn the formula itself rather than just the answer.
Our electrical calculators are built around formulas and default values referenced against recognized standards bodies — IEC for transformer and cable sizing, IEEE for motor and power system calculations, BIS for India-specific equipment ratings, and NEC for cable ampacity and installation practice where applicable. Our financial calculators are cross-checked against the published methods used by EPFO and major mutual fund houses, so the maturity and growth figures line up with how those institutions actually calculate them. That said, this site is an educational and planning resource, not a substitute for professional engineering judgment or licensed financial advice. For anything safety-critical, code-compliance related, or involving a significant financial decision, treat the calculator output as a strong starting estimate and verify it against your local electrical code or a qualified professional before acting on it. Our Disclaimer covers this in more detail, and our Editorial Policy explains how we research, verify, and update every calculator and article on the site.
There's no paywall or subscription anywhere on ElectroMechCalc, and there isn't one planned for the core calculators. The site started as a set of personal spreadsheets used on the job and grew from there — the goal was always to make a fast, accurate number available to anyone who needed it, not to build a gated product. The site is supported by advertising rather than by charging for access, which is also why the calculators are built to load quickly and work reasonably well even on a slow mobile connection at a job site, where waiting for a page to load can matter as much as the calculation itself.
A lot of engineering calculator sites are built primarily for a desktop, in a quiet office, with a stable connection. That's not always where these numbers are actually needed. ElectroMechCalc is designed to work on a phone with limited data, standing next to a distribution panel or a pump skid, with minimal typing and a result that appears as soon as the inputs are filled in. The same simplicity also makes the site useful in a classroom or a study session, where the priority shifts from speed to understanding — seeing the formula next to the result helps connect the calculation back to the theory behind it.
This is a small, actively maintained site, and the calculator list keeps growing based on what people actually ask for. If you spot an error in a formula or a result, want a calculator that doesn't exist yet, or have feedback on how an existing tool works, the fastest way to reach us is through the Contact page. Every message is reviewed, and corrections in particular are taken seriously — accuracy is the entire point of a site like this, and a wrong formula is worth fixing quickly. You can read more about who writes and reviews this content on our About page.
