What is the ideal seat height for a dining chair?

For a standard 750mm dining table, seat height should be 430-460mm for most adults. This is based on the popliteal height (back of knee to floor), which is approximately 24% of body height. Too high and feet dangle; too low and thighs are angled upward, which is uncomfortable for eating.

What angle should a chair back be?

For a dining chair, the back should be 93-97 degrees from the seat (just past vertical). For a reading or relaxed chair, 100-105 degrees. For a lounge or recliner, 110-115 degrees. The seat should also tilt back slightly (3-5 degrees for dining, up to 12 degrees for a lounge chair) to keep the sitter from sliding forward.

How much leg splay should a chair have?

Typically 3-7 degrees outward. Dining chairs use 3-5 degrees for a clean look while maintaining stability. Lounge chairs benefit from 7-10 degrees for a wider, more stable base. The splay must be compound — outward both to the front/back and to the sides. A wider splay makes the chair more tip-resistant.

How deep should a chair seat be?

The seat depth should be about 50mm less than the buttock-to-popliteal length, to avoid pressing into the back of the knees. For an average adult (175cm tall), this is about 400mm. Too deep and the sitter cannot use the backrest; too shallow and there is insufficient thigh support.

What height should armrests be?

Armrests should be about 200-250mm above the seat surface. This allows the forearms to rest naturally with shoulders relaxed. Too high forces the shoulders up; too low causes the user to lean sideways. For dining chairs, armrests must clear under the table apron — typically 630mm from the floor.

WoodCalcs

Chair Angle Calculator — Ergonomic Dimensions

Calculate seat height, angle, back angle, leg splay and armrest height for custom chairs based on user height.

User Height

Height of the primary chair user

Seat Height (optional override)

0 = auto-calculate from height

Chair Style

Determines back angle and seat tilt

How We Calculate This

This calculator uses anthropometric proportions to derive ergonomic chair dimensions from the user's height.

Anthropometric ratios used

Popliteal height (knee): ~24% of body height
Buttock-popliteal (seat depth): ~26% of body height
Hip breadth (seat width): ~22% of body height + clearance
Shoulder height (back): ~34% of body height from seat

Angle relationships

The seat angle and back angle work together. As the back reclines more, the seat tilts back further to prevent the sitter sliding forward. The calculator adjusts both angles based on your chair style preference.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.