HVAC Calculators Hub: Tonnage, CFM, Duct & Chiller

This HVAC calculators hub gathers seven free tools for cooling tons/BTU/h, ACH→CFM ventilation, duct size, static pressure, fan laws, psychrometrics, and chiller tonnage—for workshop, warehouse, and facility planning.

Pick the step that matches your question—cooling size, ventilation, duct / ESP, or plant tons. All paths share the workflow below. For electrical feeder impact, continue to the Power Calculator hub.

Most popular: HVAC capacity calculator (tons / BTU/h / cooling-load screen)—then CFM / ACH and duct size / ductulator.

What are HVAC Calculators?

HVAC calculators on this hub cover the practical decision chain: first-pass cooling and heating load (tons, BTU/h, kW), ventilation airflow (CFM from ACH), duct and ESP screening, fan affinity laws, psychrometric state points, and chilled-water plant tons. Use one structured flow for workshop, warehouse, and light-commercial planning.

Common HVAC Calculations

  • Estimate cooling size from floor area, ceiling height, occupancy, and climate band.
  • Convert sq ft rules of thumb to tons and BTU/h for budgeting (validate with Manual J before procurement).
  • Convert room volume and ACH targets to CFM for fan and duct screening.
  • Screen round or rectangular duct diameter from CFM with the HVAC duct size calculator.
  • Tie HVAC kW into factory load and energy cost screening on the Power hub.

Start Here

Most popular — HVAC capacity / tonnage: Use the HVAC capacity calculator for hvac capacity calculator, hvac tonnage calculator, and facility cooling load screening (not Manual J shopping).

Need a CFM calculator? Start with the CFM calculator (ACH to CFM) for room ventilation airflow—not compressor CFM.

Need duct size / ductulator? After CFM is known, use the duct size calculator (velocity-method screen; 12×12 CFM chart; before Manual D).

Need wet bulb / dew point? Use the psychrometric calculator (same page as wet-bulb calculator).

Browse all HVAC calculators · Browse planning topics · HVAC sizing authority guide

Cluster authority: HVAC sizing

For the HVAC cluster, cooling load sizing is the central knowledge entity—sensible and latent components, climate inputs, and rules of thumb tie into the size and ventilation tools on this hub. Start with the authority guide, then use calculators below.

HVAC Sizing Guide

Industrial cooling load methodology, rules of thumb vs detailed methods, climate inputs, and verification—the canonical HVAC sizing reference on CalcPanel.

Open HVAC Sizing Guide →

How to Calculate HVAC Capacity

Step-by-step capacity estimation with calculator links—worked inputs for workshop and utility-room screening.

How to Calculate HVAC Capacity →

Core Tools

HVAC Capacity Calculator

Estimate cooling/heating capacity and tonnage (tons, BTU/h, kW) from floor area, occupancy, and climate—facility cooling-load screen.

Use Calculator →

CFM Calculator (ACH to CFM)

Convert air changes per hour and room volume to CFM, m³/h, and L/s for fan and duct screening.

Use Calculator →

Duct Size Calculator (Ductulator)

Convert CFM and design velocity into duct area, round diameter, or rectangular trunk size—online ductulator-style screen.

Use Calculator →

HVAC Duct Static Pressure Calculator

Estimate duct friction rate and external static pressure from CFM, duct size, length, and fittings.

Use Calculator →

HVAC Fan Laws Calculator

Scale fan CFM, static pressure, and brake HP with affinity laws from RPM or target airflow.

Use Calculator →

Chiller Tonnage Calculator

Screen chilled-water plant tons from GPM × ΔT or known cooling load BTU/h—with an explicit safety factor.

Use Calculator →

Psychrometric Calculator

Dew point, wet bulb, humidity ratio, and approximate enthalpy from dry-bulb and relative humidity.

Use Calculator →

Calculation Workflow

  1. Recommended full flow: HVAC sizechiller tonnage (CHW plant) → psychrometricsACH to CFMHVAC duct sizeduct static pressurefan lawsIndustrial HVAC DesignEnergy Estimator → verify kW on Factory Load.
  2. Size-first path: HVAC size calculatorHow to Calculate HVAC Capacity → re-run size with safety margin.
  3. Ventilation-first path: ACH to CFMduct sizestatic pressureHVAC size when you also need tonnage context.
  4. Shortcut (approximate): HVAC sizeEnergy Estimator when you skip formal CFM and duct checks.

HVAC planning topics

Beyond the core calculators, these topics cover sq ft sizing, climate bands, ventilation, duct diameter, and handoff to Power tools for electrical and energy impact.

Cooling size (area → tons → BTU/h)

Screen block cooling and heating load before Manual J or stamped engineering—one calculator, this hub. Sq ft rules and IECC zone factors live on the size calculator Formula section and FAQ.

  1. HVAC size calculator — tons, BTU/h, and kW from area, height, occupancy, IECC zone
  2. How to Calculate HVAC Capacity — worked examples and assumptions
  3. HVAC Load vs Capacity — difference for procurement conversations

Guides: HVAC Sizing Guide · Capacity calculation examples · Common sizing mistakes

Psychrometrics (dew point · wet bulb · enthalpy)

When moisture or coil leaving conditions matter, screen air-state properties before locking tonnage or outdoor-air strategy.

  1. Psychrometric calculator — dew point, wet bulb, humidity ratio, approximate enthalpy from dry-bulb and RH
  2. HVAC size calculator — return to tons / BTU/h after moisture context is set

Ventilation (ACH → CFM)

After tonnage context (or in parallel), convert target air changes and room volume into supply airflow for fans.

  1. ACH to CFM calculator — CFM, m³/h, and L/s from floor area, ceiling height, ACH
  2. HVAC fan laws calculator — scale CFM, SP, and BHP when RPM or target airflow changes
  3. Industrial HVAC Design — duct distribution and plant layout context

Duct / trunk size (CFM → diameter → ESP)

When CFM is known, screen free area and round or rectangular size with the velocity method, then friction/ESP—not Manual D.

  1. HVAC duct size calculator — area, round Ø, or rectangular sides from CFM and ft/min
  2. HVAC duct static pressure calculator — friction rate and duct + fitting ESP screen
  3. Industrial HVAC Design — duct sizing — velocity bands and plant narrative

HVAC applications & deployment (hub absorb)

Scenario SERPs for warehouse AC shopping and data-center OEM pages are not Tier S landings here. Use these short cards to enter the calculator workflow—then size load, CFM, ducts, or CHW plant on the tools below.

Warehouse & high-bay HVAC planning

Description: Warehouse cooling is a facility planning problem (tons, high-bay ACH, duct/ESP)—not a window-unit shopping list. Start with block cooling load, convert the occupied height band to CFM, then screen trunks and fan ESP before vendor shortlists.

Typical load: Often 20–40+ BTU/h per sq ft for comfort cooling in occupied zones; process heat, dock doors, and clear height dominate peaks. Screen with the HVAC capacity calculator (warehouse example) and CFM / ACH using true clear height.

Recommended path: Capacity → ACH/CFM → duct sizestatic pressure. Portable “warehouse air conditioner” rental/shopping queries stay off this hub as product SERP.

Start warehouse load screen →

Data center HVAC screening (hub summary)

Description: Data-center HVAC is thermal management (sensible IT load, humidity, redundancy)—OEM CRAC/CRAH pages own brand SERP. On CalcPanel, screen plant tons and air-state first, then electrical impact on the power hub.

Typical load: IT kW × ~3,412 BTU/h per kW plus UPS/PDU losses; latent is usually small vs comfort spaces. Use capacity for block tons, psychrometrics for dew-point/wet-bulb leaving-air checks, and chiller tonnage when CHW plants serve CRAH coils.

Recommended path: IT/facility load → psychrometric screen → chiller GPM×ΔT → factory load for feeder kW. Full CFD / ASHRAE thermal guidelines remain engineer-of-record scope.

Start CHW plant tons →

Use Cases

Which HVAC Calculator Should You Use?

GoalRecommended Tool or Guide
Estimate cooling size / tonnage / BTU/h / capacityHVAC capacity calculator
HVAC size by square feetHVAC size calculator (sq ft rules in tool FAQ)
HVAC size by climate zoneHVAC size calculator (IECC zone dropdown)
Understand load vs installed capacityHVAC Load vs Capacity Guide
Recheck after occupancy or process heat changeHVAC size calculator + How to Calculate HVAC Capacity
Dew point / wet bulb / humidity ratioPsychrometric calculator
BTU/h ↔ tons conversionHVAC size calculator (built-in converter)
Duct / trunk size / ductulator from CFMDuct size calculator
CFM from ACH (ventilation CFM calculator)CFM calculator (ACH)
Duct friction / external static pressureHVAC duct static pressure calculator
Fan speed / affinity laws (CFM, SP, HP)HVAC fan laws calculator
Chiller plant tons (GPM × ΔT)Chiller tonnage calculator
Diffuser / grille free areaHVAC duct size (diffuser table)
Duct airflow (ACH → CFM) screeningACH to CFM calculator
Plant-wide electrical impact of HVAC kWPower CalculatorFactory Load
Annual HVAC operating costIndustrial Energy Estimator

Intent split: The HVAC calculator (/tools/hvac-capacity) owns hvac calculator / tonnage / BTU sizing SERP. This hub (/hvac-calculator) is the planning index—use it for workflow navigation, then open the matching task tool above.

HVAC Sizing Long-Tail Queries (Square Feet, Climate, Duct)

Generic “HVAC size calculator by zip code” queries route to the HVAC size calculator. Separate hvac duct size calculator intent uses the duct size tool—not as thin house/filter pages.

  • Square feet / system / unit size: HVAC size calculator — also covers calculate hvac size, hvac system size calculator, and hvac unit size calculator.
  • Zip code / climate: Pick your IECC climate zone on the size calculator—see the zone → factor table in that page’s Formula section.
  • Duct / trunk size: Get CFM with ACH to CFM, diameter with HVAC duct size calculator, then ESP with duct static pressure; use fan laws for RPM/VAV changes.

Deep methodology: How to Calculate HVAC Capacity · HVAC Sizing Guide.

Related Guides

Partner Hub: Power Systems

HVAC kW feeds into facility demand and feeder sizing. Use the Power Calculator hub for factory load roll-up, transformer and generator context, and the Electrical hub for breaker and cable checks on HVAC feeders.

FAQ

What is an HVAC calculator used for?

This hub helps you pick the right free tool—cooling size (tons, BTU/h) or ventilation (CFM)—before detailed HVAC engineering. It does not replace Manual J or stamped loads for permit drawings.

Which HVAC calculator should I start with first?

For tonnage or BTU/h, start with the HVAC size calculator. For fan or duct airflow, start with ACH to CFM. Return to this hub when you need the full workflow.

Is there an HVAC size calculator by square feet?

Yes—use the HVAC size calculator with your floor area. The tool lists common BTU/h per square foot rules of thumb for US budgeting in its FAQ.

Can I size HVAC by zip code or climate zone?

Select your IECC climate zone on the HVAC size calculator. Zip-specific Manual J data still requires local design temperatures for permit drawings.

Which tool covers HVAC duct size or CFM?

Estimate tonnage on the HVAC capacity calculator first; then use the CFM calculator (ACH) for airflow, duct size / ductulator for diameter (includes diffuser/grille face-area screen), duct static pressure for ESP, and fan laws for RPM/VAV scaling. For chilled-water plant tons use the chiller tonnage calculator.

Where is the online ductulator or wet bulb calculator?

Ductulator / duct size: duct size calculator (CFM + velocity → round/rect; 12×12 CFM chart). Wet bulb: psychrometric calculator—same free page, no separate URL. Warehouse AC shopping queries stay on this hub summary only (no Tier S product page).

Do you have a warehouse air conditioner or data center HVAC page?

No Tier S shopping pages. Warehouse AC product SERPs and OEM data-center brands are absorbed as planning cards under HVAC applications—use capacity, CFM, duct/ESP, psychrometric, and chiller tools instead of portable-AC storefronts.

Do you have refrigerant charge or SEER savings calculators?

No dedicated tools—those SERPs are OEM line-charge apps and residential SEER shopping. For facility energy use, continue with the energy estimator; for capacity keep using HVAC size.

What is the difference between this hub and the HVAC size calculator?

This page (/hvac-calculator) is the HVAC calculators hub for navigation and workflow. The HVAC size calculator is the interactive tool for tons, BTU/h, and kW results—use it when your query is task-specific (size, capacity, sq ft).

How to calculate HVAC capacity for workshop retrofit?

Start with area and thermal assumptions in the HVAC size calculator, then update occupancy, process heat, and ventilation. See How to Calculate HVAC Capacity for worked steps.