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Introducing Enginist: 100% Free Engineering Calculators

Enginist provides free professional engineering calculators with transparent formulas, standards references, and no paywalls. Power factor, voltage drop, HVAC sizing, pump calculations - all free, forever.

Enginist Team
Published: October 15, 2025
Updated: December 16, 2025
#launch#engineering calculators#free engineering tools#platform announcement

Table of Contents

Why We Built Enginist

Engineering calculations shouldn't require expensive subscriptions or unreliable spreadsheets.

We've all been there: the Excel file named "v3_FINAL_USE_THIS_ONE.xlsx" with hidden formula errors. Or the quote for engineering software that costs thousands per year for seats you can't justify.

Enginist solves this. Every calculator is free, shows its formulas, and references the actual standards.

What Makes Enginist Different

1. Transparent Formulas

Every calculator shows exactly how results are calculated. Click "Show Formulas" to see equations, variable definitions, and standards references. During code compliance reviews, you can point to the exact formula and standard clause.

2. Standards-Based

All calculations reference recognized standards:

DomainStandardsCoverage
ElectricalIEEE, IEC, NECPower factor, voltage drop, cable sizing
HVACASHRAECooling load, psychrometrics, ventilation
Fire ProtectionNFPASprinkler, hydrant systems
StructuralIBC, AISCBeam deflection, section properties
PlumbingIPC, UPCPipe sizing, water systems

3. Actually Free

No trials. No premium tiers. No per-seat licensing.

Everything is free:

  • ✅ All 68+ calculators
  • ✅ PDF export
  • ✅ Shareable links
  • ✅ Calculation history
  • ✅ Unit conversion
  • ✅ Dark mode
  • ✅ Mobile-responsive design

Available Calculators

Electrical

HVAC

Mechanical

Quick Example: Power Factor Calculation

Scenario: A manufacturing plant is paying penalties for poor power factor. Management needs a business case for capacitor banks.

The required capacitor bank size is calculated using:

Qc=P×(tan⁡ϕ1−tan⁡ϕ2) kVARQ_c = P \times (\tan\phi_1 - \tan\phi_2) \text{ kVAR}

Where PP is real power in kW, ϕ1\phi_1 is current power factor angle, and ϕ2\phi_2 is target power factor angle.

Traditional approach: Build an Excel spreadsheet (2-4 hours) or hire a consultant (3,000-5,000 USD).

With Enginist:

  1. Open the Power Factor Calculator
  2. Enter your measured data (5 minutes)
  3. Get required capacitor size, annual savings, and payback period
  4. Export as PDF for management presentation

Total time: 10 minutes. Cost: Free.

Second Example: Voltage Drop Verification

Scenario: An electrician needs to verify that a 150m cable run to an HVAC unit meets NEC voltage drop requirements.

Problem Statement

  • Load: 3-phase motor, 15 kW at 400V
  • Cable length: 150 m (one-way)
  • Proposed cable: 6 mm² copper
  • Voltage drop limit: 3% per NEC guidelines

Step 1: Calculate Current

I=P3×V×pf×η=15,0003×400×0.85×0.9=28.3 AI = \frac{P}{\sqrt{3} \times V \times pf \times \eta} = \frac{15,000}{\sqrt{3} \times 400 \times 0.85 \times 0.9} = 28.3 \text{ A}

Step 2: Calculate Voltage Drop

Using the formula for 3-phase circuits:

Vdrop=3×I×L×(R×cos⁡ϕ+X×sin⁡ϕ)1000V_{drop} = \frac{\sqrt{3} \times I \times L \times (R \times \cos\phi + X \times \sin\phi)}{1000}

For 6 mm² copper at 75°C: R = 3.08 Ω/km, X = 0.08 Ω/km

Vdrop=3×28.3×150×(3.08×0.85+0.08×0.527)1000V_{drop} = \frac{\sqrt{3} \times 28.3 \times 150 \times (3.08 \times 0.85 + 0.08 \times 0.527)}{1000} Vdrop=3×28.3×150×2.661000=19.6 VV_{drop} = \frac{\sqrt{3} \times 28.3 \times 150 \times 2.66}{1000} = 19.6 \text{ V}

Step 3: Check Against Limit

%Vdrop=19.6400×100=4.9%\% V_{drop} = \frac{19.6}{400} \times 100 = 4.9\%

Result: 6 mm² cable FAILS (4.9% > 3% limit)

Step 4: Upsize Cable

Try 10 mm² (R = 1.83 Ω/km):

Vdrop=3×28.3×150×1.581000=11.6 V=2.9%V_{drop} = \frac{\sqrt{3} \times 28.3 \times 150 \times 1.58}{1000} = 11.6 \text{ V} = 2.9\%

Result: 10 mm² cable PASSES ✓

Use our Voltage Drop Calculator to verify cable sizing for any installation.

Platform Features

Works Everywhere

  • Desktop: Full-featured experience
  • Tablet: Perfect for on-site reviews
  • Mobile: Field calculations on the go
  • Offline: Install as PWA for offline access

Built for Engineers

  • Unit conversion: Seamless metric/imperial switching
  • Dark mode: Reduce eye strain
  • Print-friendly: Clean summaries for documentation
  • Fast: Less than 2 second page loads globally

Share Your Work

  • PDF export: Professional calculation reports
  • Shareable links: Send calculation scenarios to colleagues
  • Calculation history: Track your recent calculations

For Students and Small Firms

Students: Learn with the same tools professionals use. Understand formula derivations, not just answers. Build portfolio projects that impress hiring managers.

Small firms: Compete on engineering skill, not software budget. No more rationing expensive software seats. Every engineer gets access to every calculator.

Facilities engineers: Make immediate impact. Calculate savings, build business cases, get projects approved - all without waiting for procurement.

Technical Standards

Every Enginist calculator is:

  • Validated against published worked examples
  • Cross-checked with commercial software
  • Reviewed before release
  • Documented with assumptions and limitations

We target less than 2% deviation from standard reference values. All formulas are visible for independent verification.

Why Not Just Use Excel?

We've all inherited that engineering spreadsheet - the one passed down through three job changes, with formulas nobody fully understands anymore. Here's why purpose-built calculators are better:

IssueExcel SpreadsheetEnginist Calculator
Version control"final_v3_USE_THIS.xlsx"Always current, centrally maintained
Formula errorsHidden in cells, hard to auditVisible, validated against standards
Unit handlingManual conversion, error-proneAutomatic metric/imperial switching
Standards updatesYou track and update manuallyWe handle IEEE/ASHRAE/IEC updates
DocumentationOften missing or outdatedBuilt-in formula explanations
SharingEmail attachments, version conflictsShareable links with state preservation

The Real Cost of Spreadsheet Errors

Studies show that 88% of spreadsheets contain errors. In engineering, these errors can mean:

  • Undersized electrical systems causing failures
  • HVAC systems that don't meet load requirements
  • Structural elements that don't meet code

Enginist calculators eliminate entire categories of spreadsheet errors by enforcing correct formula application and unit handling.

Calculation Accuracy Verification

Our validation process for each calculator includes:

  1. Standard verification: Compare results against published worked examples in IEEE, ASHRAE, IEC standards
  2. Cross-software validation: Check against commercial engineering software where available
  3. Edge case testing: Verify behavior at boundary conditions (minimum/maximum values)
  4. Unit consistency: Test all supported unit combinations for correct conversion

For example, our Voltage Drop Calculator has been verified against:

  • IEEE Std 141 (Red Book) worked examples
  • NEC Chapter 9 Table 9 conductor properties
  • Commercial cable sizing software outputs

All verification data is available upon request for critical applications.

Third Example: Duct Sizing for HVAC

Scenario: An HVAC contractor needs to size a supply duct for an office renovation.

Problem Statement

  • Required airflow: 850 L/s
  • Target friction rate: 1.0 Pa/m (equal friction method)
  • Available space: 300mm ceiling cavity
  • Duct material: Galvanized steel

Solution Using Enginist

  1. Open the Duct Sizing Calculator
  2. Enter: Flow = 850 L/s, Friction = 1.0 Pa/m

Result

Duct OptionDimensionsVelocityFits 300mm?
RoundØ400mm6.8 m/s✗ Too tall
Rectangular 2:1500×250mm6.8 m/s✓ Yes
Rectangular 3:1600×200mm7.1 m/s✓ Yes

Selected: 500×250mm rectangular duct (lower aspect ratio = less fabrication cost)

Total time: 2 minutes with Enginist vs. 20+ minutes with charts and tables.

Get Started

No registration required. Just pick a calculator and start.

  1. Browse all calculators - Find the tool you need
  2. Enter your data - Get instant results with formula transparency
  3. Export or share - PDF reports and shareable links included

The Enginist Team

Building better tools for engineers, completely free.

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