Shelf Sag and Load Calculator (The Sagulator)
The shelf sag and load calculator (Sagulator) estimates how much a shelf will bend under the weight of books, audio equipment, tools, or dishware based on span length, material stiffness, and thickness.
Shelf parameters
Load share per bracket: 16 kg (3 pcs кронштейнів)
Rigid structure, deflection is virtually imperceptible
• 1 meter of paperback/hardcover books ≈ 25-30 kg
• Stack of 12 dinner ceramic plates ≈ 6-8 kg
• Canned jars (3 Liters) ≈ 4.5 kg each
Shelf installation best practices
How to use
- Select your shelf material (hardwood, softwood, plywood, MDF, or particle board).
- Enter unsupported span length between brackets.
- Input shelf depth and thickness.
- Choose wall anchor substrate (concrete, brick, stud, or drywall).
- Review total sag deflection in mm/inches and safety rating.
Acceptable Shelf Sag Criteria
Woodworking standards consider a sag of 1/300 to 1/360 of the unsupported span (less than 0.033 inches per foot) visually acceptable and structurally sound.
Frequently Asked Questions
What is the maximum span for a bookshelf?
Standard 3/4-inch (18-19mm) plywood or solid wood handles spans up to 30-36 inches (75-90 cm). 5/8-inch (16mm) particle board should not exceed 24 inches (60 cm) under full book loads.
Related Tools
Compound Interest Calculator
Calculate monthly investment growth with compounding interest.
Habit Cost Calculator
Calculate how much your daily habits cost per year and across 10 years.
Subscription Optimizer
Analyze all your subscriptions and find unnecessary expenses.
Cash Loan Calculator
Calculate monthly payment, total interest, and comparison between annuity and differentiated loans.