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Chair Seat Height Calculator — Ergonomic Chair Dimensions
Calculate ergonomic chair dimensions based on user height for comfortable seating.
How We Calculate This
This calculator uses anthropometric proportions to determine ergonomic chair dimensions from user height.
Key relationships
Seat height = Popliteal height = approx. 25% of body height
The result is the bare-foot popliteal height. For shod users, add roughly 25-30mm for footwear so the seat still holds the feet flat with the knees at about 90 degrees.
Seat depth = approx. 85% of buttock-popliteal length (buttock-popliteal length = approx. 29% of height)
Seat width = Hip breadth (22% of height) + 40mm clearance
Cushion thickness is subtracted from the seat frame height, as the compressed cushion will bring the effective sitting surface back to the target height.
Frequently Asked Questions
The standard UK dining chair seat height is 430-460mm for an average adult (1700-1800mm tall). This pairs with a standard 735mm dining table height, providing about 280-300mm of clearance between seat and table underside for comfortable thigh clearance.
Seat depth should allow you to sit with your back against the backrest while maintaining a gap of about 50-75mm between the front edge of the seat and the back of your knees. It is set to roughly 85% of buttock-popliteal length (the horizontal buttock-to-back-of-knee distance), typically 400-450mm for adults. Too deep causes slouching; too shallow gives inadequate thigh support.
Dining chairs typically have a seat tilt of 1-3 degrees backward (front higher than rear). Lounge chairs have 5-8 degrees of tilt. The backrest angle relative to the seat is usually 95-100 degrees for dining and 100-110 degrees for lounge chairs.
Armrests should support the forearms at approximately elbow height when seated, typically 180-220mm above the seat surface. Too high causes shoulder strain; too low requires leaning sideways. For dining chairs, armrests must clear under the table.
Popliteal height is the distance from the floor to the back of the knee when seated. It is the key measurement for seat height, approximately 25% of standing height. The seat should be at or slightly below popliteal height so feet rest flat on the floor without compressing the underside of the thighs.
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Last updated: February 2026
All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.