Determine the perfect curtain length for any window or door with our easy-to-use tool.
Curtain Length Calculator
Measure from the floor to the curtain rod. (Inches)
Measure from the floor to the top of the window sill. (Inches)
To the Sill
Below the Sill (4-6 inches)
Mid-way to Floor
Just Touching the Floor
Puddling on the Floor
Select how you want your curtains to end.
How much you want the curtain to pool on the floor. (Inches)
Your Curtain Length Results
Key Assumptions:
Formula Used: Curtain length is calculated based on the rod height, window sill height, and your desired finish point (sill, floor, or puddle). For puddling, an additional depth is added.
Curtain Length vs. Rod Height
Visualizing how rod height impacts the required curtain length for a 'Just Touching' finish.
Desired Finish
Calculation Logic
Typical Length (Inches)
To the Sill
Rod Height – Window Sill Height
Below the Sill (4-6″)
(Rod Height – Window Sill Height) + 4 to 6 inches
Mid-way to Floor
(Rod Height – Floor) / 2
Just Touching Floor
Rod Height – Floor (approx. 0 inches)
Puddling on Floor
Rod Height – Floor + Puddle Depth
Standard curtain length calculations based on desired finish.
Curtain Length Calculator: Measure and Buy Curtains Accurately
What is a Curtain Length Calculator?
A curtain length calculator is a simple yet invaluable online tool designed to help homeowners, interior designers, and DIY enthusiasts determine the precise length required for curtains. Instead of relying on guesswork or complicated manual calculations, this tool takes your specific window or door measurements and desired aesthetic to provide an accurate curtain length. This ensures your curtains hang beautifully, complement your decor, and function effectively, whether you want them to just touch the floor, puddle elegantly, or end precisely at the windowsill. The primary goal of a curtain length calculator is to eliminate the common mistake of buying curtains that are too short or too long, saving time, money, and potential frustration.
Who should use it: Anyone purchasing new curtains, replacing old ones, or undertaking a home renovation project. This includes renters looking to update their space, homeowners wanting a polished look, and individuals who find measuring and calculating challenging. Essentially, if you're buying curtains, you can benefit from using a curtain length calculator.
Common misconceptions: A frequent misconception is that all curtains should just touch the floor. In reality, different styles and desired looks call for different lengths. Some prefer curtains that hover slightly above the floor for ease of cleaning, while others opt for a dramatic puddle effect. Another misconception is that standard window measurements are sufficient; however, the height of the curtain rod and the desired finish point are crucial factors that a curtain length calculator helps address.
Curtain Length Calculator Formula and Mathematical Explanation
The core logic behind a curtain length calculator is straightforward geometry and arithmetic, focusing on vertical measurements. The calculation aims to find the distance from the curtain rod to the desired endpoint of the fabric.
The fundamental formula can be broken down based on the desired finish:
To the Sill: Curtain Length = Rod Height – Window Sill Height
Mid-way to Floor: Curtain Length = (Rod Height – Floor Height) / 2. Since Floor Height is 0, this simplifies to Rod Height / 2.
Just Touching the Floor: Curtain Length = Rod Height – Floor Height (effectively, Rod Height, assuming the floor is at 0 inches relative to the rod's base).
Puddling on the Floor: Curtain Length = Rod Height – Floor Height + Puddle Depth (effectively, Rod Height + Puddle Depth).
Variable Explanations:
Variable
Meaning
Unit
Typical Range
Rod Height
The vertical distance from the floor to the curtain rod.
Inches
40 – 100+
Window Sill Height
The vertical distance from the floor to the top of the window sill.
Inches
20 – 80+
Desired Length Type
The chosen aesthetic finish for the curtain's bottom edge.
N/A
Sill, Below Sill, Mid-Floor, Touch Floor, Puddle
Puddle Depth
The extra fabric length allowed to pool on the floor for a 'puddle' effect.
Inches
1 – 12+
Calculated Curtain Length
The final recommended length for the curtain fabric.
Inches
Varies greatly based on inputs
The curtain length calculator automates these calculations, ensuring accuracy and ease of use for anyone needing precise curtain measurements. Understanding the curtain length calculator formula helps in making informed decisions about curtain styles.
Practical Examples (Real-World Use Cases)
Let's illustrate how the curtain length calculator works with practical scenarios:
Example 1: Standard Window with Floor-Length Curtains
Scenario: Sarah has a living room window. She measures the distance from the floor to her curtain rod at 70 inches. The top of her window sill is 55 inches from the floor. She wants her curtains to hang straight down and just touch the floor.
Inputs for Calculator:
Curtain Rod Height from Floor: 70 inches
Window Sill Height from Floor: 55 inches
Desired Curtain Length: Just Touching the Floor
Calculator Output:
Final Curtain Length: 70 inches
Intermediate Value (Length to Floor): 70 inches
Key Assumption: Floor is level and at 0 inches relative to the rod's base.
Interpretation: Sarah needs to purchase curtains that are 70 inches long. This ensures they will hang perfectly from the rod and just graze the floor, providing a clean and elegant look.
Example 2: Bay Window with Puddling Curtains
Scenario: Mark is redecorating his bedroom and wants a luxurious feel. His bay window has a curtain rod mounted high, measuring 90 inches from the floor. He desires a dramatic puddle effect and decides he wants the curtains to pool 5 inches on the floor.
Inputs for Calculator:
Curtain Rod Height from Floor: 90 inches
Window Sill Height from Floor: (Not directly used for puddle calculation, but good to note: 60 inches)
Desired Curtain Length: Puddling on the Floor
Puddle Depth: 5 inches
Calculator Output:
Final Curtain Length: 95 inches
Intermediate Value (Length to Floor): 90 inches
Intermediate Value (Puddle Depth Added): 5 inches
Key Assumption: Floor is level.
Interpretation: Mark should buy curtains that are 95 inches long. The extra 5 inches will create the desired soft puddle on the floor, adding a touch of opulence to his bedroom.
How to Use This Curtain Length Calculator
Using the curtain length calculator is designed to be intuitive. Follow these simple steps:
Measure Rod Height: Using a tape measure, determine the exact distance from the floor to the curtain rod. Enter this value in inches into the "Curtain Rod Height from Floor" field.
Measure Sill Height (if applicable): If you're considering curtains that end at or below the sill, measure the distance from the floor to the top of the window sill. Enter this in the "Window Sill Height from Floor" field.
Select Desired Finish: Choose how you want your curtains to end from the dropdown menu: "To the Sill," "Below the Sill," "Mid-way to Floor," "Just Touching the Floor," or "Puddling on the Floor."
Enter Puddle Depth (if applicable): If you selected "Puddling on the Floor," a new field will appear. Enter the desired amount of fabric you want to pool on the floor in inches.
Calculate: Click the "Calculate Length" button.
How to Read Results: The calculator will display the "Final Curtain Length" prominently. It will also show key intermediate values and assumptions used in the calculation. The table below the calculator provides a quick reference for standard lengths.
Decision-Making Guidance:
For a formal look: Choose "Just Touching the Floor" or "Puddling on the Floor."
For practicality and ease of cleaning: Opt for "To the Sill" or "Below the Sill." Ensure "Below the Sill" curtains extend at least 4-6 inches past the sill to avoid looking too short.
For dramatic effect: Use the "Puddling on the Floor" option with a generous puddle depth (e.g., 6-12 inches).
Always consider the fabric type; heavier fabrics may puddle more naturally than lighter ones.
This curtain length calculator simplifies the process, ensuring you achieve the perfect look for your space.
Key Factors That Affect Curtain Length Results
While the curtain length calculator provides a precise measurement, several factors can influence the final decision and appearance:
Curtain Rod Placement: The height at which you install the curtain rod is the most critical factor. Mounting the rod higher on the wall can make the ceiling appear taller and requires longer curtains. The calculator uses this measurement directly.
Desired Aesthetic: As covered, the style you want—from minimalist to opulent—dictates the finish. "To the sill" is casual, while "puddling" is formal. The calculator accounts for these choices.
Floor Levelness: The calculator assumes a perfectly level floor. If your floors are significantly sloped, you might need to adjust the final curtain length slightly or have them custom hemmed.
Fabric Type and Weight: Heavier fabrics (like velvet or thick linen) tend to drape and puddle more dramatically than lighter fabrics (like sheer voile). You might want to add an extra inch or two for lighter fabrics if aiming for a puddle effect.
Presence of Radiators or Furniture: If curtains will hang over a radiator or furniture, you must choose a length that doesn't obstruct heat or function. "To the sill" or "below the sill" are often necessary in these cases.
Hem Allowance: Manufacturers often include a standard hem allowance (e.g., 2-4 inches) at the bottom of ready-made curtains. While the calculator provides the total required length, be aware of how this interacts with pre-made hems if you plan to alter them.
Shrinkage: Natural fabrics like cotton and linen can shrink when washed. If you plan to wash your curtains, consider adding an extra inch or two to the calculated length to account for potential shrinkage.
Considering these factors alongside the curtain length calculator results will lead to the most satisfactory outcome.
Frequently Asked Questions (FAQ)
Q1: What is the standard length for curtains?
A: There isn't one single "standard" length. It depends entirely on your desired look and measurements. However, floor-length curtains (just touching or puddling) are very popular for a formal or elegant feel. The curtain length calculator helps determine this precisely.
Q2: Should curtains touch the floor?
A: It's a matter of style preference. Curtains that just touch the floor offer a clean, tailored look. Puddling curtains create a more luxurious, dramatic effect. Curtains ending above the floor can look unfinished if not done intentionally (e.g., ending exactly at the sill).
Q3: How much extra should I add for puddling curtains?
A: For a subtle puddle, add 1-3 inches. For a more dramatic effect, 4-6 inches is common. Very luxurious styles might use 8-12 inches or more. The curtain length calculator allows you to specify this.
Q4: My curtains look too short. What did I do wrong?
A: The most common mistake is measuring from the window frame instead of the rod, or not accounting for the desired finish. Ensure you measure from the rod to the floor (or desired endpoint) and use a tool like the curtain length calculator.
Q5: Can I use the calculator for doors?
A: Yes! Treat the door hardware (like a rod or track) as the "curtain rod" and measure from there to your desired finish point on the floor. The principles are the same.
Q6: What if my window sill is very high?
A: The calculator handles this. If your sill height is high (e.g., 70 inches) and your rod height is 80 inches, curtains ending "To the Sill" would be 10 inches long, which is unusual. In such cases, "Just Touching the Floor" (80 inches) or "Puddling" are more common choices.
Q7: Do I need to account for the curtain heading (pleats, grommets)?
A: The calculator measures the total fabric length needed from the rod. How the fabric attaches (grommets, rod pocket, pleats) affects where the fabric *starts* hanging relative to the rod. For most standard measurements (like grommets or rod pockets), measuring from the rod itself is accurate. For pinch pleats, you might need slightly less length as the pleats shorten the effective drop.
Q8: How do I measure for double curtains (e.g., sheer and blackout)?
A: Measure each set independently using the curtain length calculator. Sheer curtains might be floor-length, while blackout curtains hung on the same rod might be slightly shorter (e.g., just touching the floor) for practicality.
Related Tools and Internal Resources
Curtain Width CalculatorHelps determine the optimal width for your curtains based on rod size and desired fullness.