Range Hood Size Calculator & Kitchen Ventilation Measurement Guide

Plan range hood width, rough CFM band, mounting height, duct awareness, and replacement measurements before comparing products or asking an installer.

This range hood size calculator is built for homeowners, remodelers, landlords, and cabinet planners who need a conservative pre-shopping worksheet. It turns cooktop width, hood style, fuel type, cooking intensity, kitchen openness, duct assumptions, cabinet opening, and mounting height into a practical planning range. The output is not a permit drawing or installation instruction, but it helps you collect the measurements a qualified installer, appliance dealer, or ventilation professional will ask for.

How to use the range hood size calculator

Start with the actual cooking surface width, not just the cabinet label or appliance model name. A common wall or under-cabinet hood is often planned at least as wide as the cooktop, while an island hood may need extra capture width because smoke and steam can escape from every side. Enter the cabinet or ceiling opening separately so the calculator can flag when the hood body may not fit the available space.

The CFM band is intentionally described as a rough planning range. The calculator begins with cooktop width, then adjusts for gas or induction appliances, cooking intensity, open-plan rooms, island exposure, and whether the unit is ducted or recirculating. Real requirements can change after a pro reviews BTU output, duct size, equivalent duct length, elbows, termination, make-up-air rules, noise targets, and manufacturer tables.

Inputs and outputs included

• Cooktop and hood width: compares planned capture width with wall, under-cabinet, insert, island, or recirculating layouts.
• Cabinet/opening width: warns when a chosen hood may be wider than the available upper-cabinet gap or trim area.
• Fuel and cooking intensity: adjusts the ventilation planning band for electric, induction, gas, light cooking, everyday cooking, or heavy searing.
• Duct assumptions: records duct diameter, approximate run length, elbows, and recirculating situations so obvious restrictions are visible before purchase.
• Mounting height: checks whether the planned distance above the cooking surface is in a broad conservative range and reminds you to follow the exact manuals.

Calculation logic in plain English

The width estimate starts from the cooktop width. Wall and under-cabinet layouts usually use the cooktop width as a minimum planning target, inserts follow the liner/enclosure requirement, and island hoods add a wider capture allowance. The CFM planning band starts from a width-based estimate, then applies multipliers for gas heat, induction, cooking intensity, open kitchens, island exposure, and recirculating limitations. The tool also raises review notes when the duct is narrow, the run is long, there are multiple elbows, or the proposed mounting height is outside a conservative planning window.

Real planning examples

Replacing a 30 inch under-cabinet hood: a homeowner with a 30 inch gas cooktop, 30 inch cabinet opening, 6 inch duct, and two elbows can use the tool to confirm that a 30 inch replacement is plausible, then check the manual for mounting height, duct size, and make-up-air rules before ordering.

Planning a kitchen island: a 36 inch cooktop on an island often needs a wider capture target than a wall hood. The calculator flags the extra width allowance and reminds the planner to verify ceiling support, duct route, sight lines, and manufacturer chimney limits.

Considering a recirculating unit: a renter or condo owner without an outside duct can mark the hood as recirculating. The output lowers expectations for odor and grease removal and highlights filter access, product limits, and building rules.

Checking a long duct route: a remodeler with a roof termination, transition, and several elbows can use the duct inputs to spot a likely restriction early. That warning does not size the duct, but it tells the team to review equivalent length, damper condition, termination clearance, and noise expectations before choosing a powerful blower.

Before buying or installing

Use the results as a measurement checklist, then verify the hood manual, cooking appliance manual, cabinet structure, electrical supply, gas safety, duct route, wall or roof termination, make-up-air requirement, local code, permit requirement, and warranty language. Do not cut cabinets, penetrate a wall or roof, alter gas/electrical service, or assume a high-CFM hood is allowed without qualified professional review.

FAQ

How wide should a range hood be? Use the cooktop width as a basic wall-hood planning minimum and consider extra capture for island layouts. Confirm the exact product manual.

Is the CFM number a code requirement? No. It is a planning band only. Codes, make-up-air rules, duct limits, appliance BTU, and manufacturer instructions control the real decision.

Can this choose a duct size? No. It records duct concerns and tells you what to verify with a qualified ventilation professional.

Does this site include live ads or commercial product links? No. It only contains reserved future advertising space and no product partner links.

General non-installation planning only. Verify manufacturer instructions, local code, make-up-air, ducting, electrical, gas, cabinet support, and qualified professional requirements.