Skip to content

Header Size Calculator

Prepare preliminary opening and load inputs before checking an approved header table or engineered design.

Reviewed
2026-09-05
Units
US + metric

Calculated result / live

10.5 ft header length

Provide about 10.50 ft of header length, including 3.0 in bearing at each end.

A 10.00 ft opening with 3.0 in bearing on two sides. This sizes length only, not member depth or ply count.

Input panel

Project measurements

Secondary quantities
Opening10.00 ft
Total bearing6.0 in
Minimum header length10.50 ft

Calculation trace

Formula with your numbers

10.00 ft + (2 × 3.0 in ÷ 12) = 10.50 ft

10.5 ft header length
01

What this header size calculator calculates

A 6 ft opening with 3 in bearing at each side needs 6.50 ft of header length before cuts.

Formula

Opening width + (bearing per side × 2) ÷ 12 = minimum header length.

Worked example

6 ft + (3 in × 2 ÷ 12) = 6.50 ft. The length does not prove that a 2 × 10 or any other member is adequate.

Ordering decision

Use the approved header table or engineered design for roof, floor, wall, snow, wind, and point loads.

The page cites the applicable Uzi Tools reference table beside the calculator. Product labels, current editions, local code, and a licensed professional govern structural, electrical, and life-safety work.

02

How to use it

  1. Enter the measured dimensions and keep the displayed units beside each field.
  2. Review the header length and bearing result and the substituted formula before ordering.
  3. Adjust waste for the layout, cut pattern, product package, and site conditions.
  4. Copy or print the material list, then verify the cited product data and local requirements.
03

Header length and bearing

This header calculator checks the preliminary cut length from opening width and bearing at both ends. It does not select a header depth, species, ply count, or load capacity.

04

Limits and professional review

Measurements, product yield, waste, moisture, and site conditions can change the order quantity. Local code and a licensed professional govern structural and electrical work.

05

Data sources

06

Related calculations

07

Same-project tools

08

Questions specific to this estimate