What This Calculator Does

This Window Blind Size Calculator helps you estimate finished blind width and length for inside mount, outside mount, ceiling mount, door mount, and bay window configurations. It calculates fabric yardage, hardware brackets, cord/stack length, and child-safety cordless options for roller, roman, cellular, wood, faux wood, vertical, mini, and motorized blinds.

The calculation features automatic deduction for mullions, handles, sensors, and vents, plus detailed cost breakdowns including hardware, fabric, valance, lift mechanisms, installation, and delivery.

How to Use the Window Blind Size Calculator

1. Select your preferred measurement system (Imperial inches or Metric cm) and target blind type. Selecting a blind type automatically adjusts default width, length, and fabric treatment.
2. Choose your application / window location (living room, bedroom, kitchen, etc.) — this auto-suggests appropriate fabric treatment and safety features.
3. Select the mount type (inside, outside, ceiling, door, or bay) and enter the corresponding dimensions.
4. Optionally use a project template to auto-fill dimensions for common windows like a standard bedroom, sliding door, or bay window.
5. Add deductions for mullions, handles, sensors, and vents to refine blind sizing and hardware requirements.
6. Configure optional hardware and safety features like valance, cordless lift, light gap reducer, stack accommodation, and hold-down brackets.
7. Optionally enter pricing for hardware, fabric, labor, and installation to generate a complete financial estimate.
8. Adjust the waste slider to configure your safety margin, then click Calculate Blind Size & Order.

Blind Size Reference Chart

Common Window Blind Questions

Pro Tips for Accurate Blind Measurement

• Use a steel tape measure — cloth or laser can give inconsistent readings on window frames.
• Measure each window separately — no two windows are exactly the same size.
• Note any out-of-square windows — use outside-mount if the frame is significantly skewed.
• Check obstructions — handles, locks, alarm sensors, and HVAC vents affect blind clearance.
• Verify frame depth — inside-mount requires at least 1.5–2 inches for brackets and hardware.
• Choose cordless for child or pet rooms — bedrooms, playrooms, and family rooms.
• For motorized blinds verify power source proximity — battery, plug-in, or hardwired.
• Round DOWN inside-mount measurements; round UP outside-mount measurements.

Complete Guide to Window Blind Sizing & Costs

Getting the right blind size is essential for proper fit, light control, and energy efficiency. This guide covers everything from measuring to installation.

Understanding Inside Mount vs Outside Mount

Inside mount blinds fit inside the window frame — they look clean and streamlined but require sufficient frame depth. Outside mount blinds cover the entire window opening and overlap the trim — they block more light and work well for out-of-square windows.

Choosing Fabric Type and Light Control

Blackout fabrics block 100% of light — ideal for bedrooms and media rooms. Light filtering fabrics soften glare while maintaining daytime privacy. Solar screen fabrics reduce heat and UV glare while preserving outward visibility.

Hardware Requirements: Brackets, Lift Mechanisms, Valances

Every blind needs mounting brackets (1 per 30 inches + 2 per blind). Lift mechanisms include standard cord, cordless, continuous loop, motorized, and wand tilt. Valances cover the headrail for a finished look — available in square, crown, or curved styles.

Hidden Costs: Custom Sizing Fees, Installation, Motor Wiring

Beyond the blind itself, budget for custom sizing fees ($10–30 per blind), professional installation ($25–50 per blind), motor wiring ($50–150), and smart home integration ($20–50). Our calculator includes all these optional cost fields to give you a complete project estimate.