Compound Bow Draw Length Calculator

Compound Bow Draw Length Calculator

Inches (Standard) Centimeters (Metric)

Measure from the tip of one middle finger to the other with arms outstretched.

Calculated Draw Length

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function updateLabels() { var unit = document.getElementById('unitSystem').value; var label = document.getElementById('spanLabel'); var input = document.getElementById('wingspanInput'); if (unit === 'cm') { label.innerText = "Your Wingspan (Centimeters):"; input.placeholder = "e.g. 178"; } else { label.innerText = "Your Wingspan (Inches):"; input.placeholder = "e.g. 70"; } } function calculateBowDraw() { var wingspanValue = parseFloat(document.getElementById('wingspanInput').value); var unit = document.getElementById('unitSystem').value; var resultDiv = document.getElementById('resultDisplay'); var valDiv = document.getElementById('drawLengthValue'); var recDiv = document.getElementById('recommendationText'); if (isNaN(wingspanValue) || wingspanValue <= 0) { alert("Please enter a valid wingspan measurement."); return; } var wingspanInInches; if (unit === 'cm') { wingspanInInches = wingspanValue / 2.54; } else { wingspanInInches = wingspanValue; } // The industry standard formula: Wingspan / 2.5 var drawLength = wingspanInInches / 2.5; var roundedDraw = Math.round(drawLength * 2) / 2; // Round to nearest 0.5 inch resultDiv.style.display = "block"; valDiv.innerText = roundedDraw + "\""; var advice = ""; if (roundedDraw 30) { advice = "This is a long draw length; ensure the bow model you select supports this range."; } else { advice = "This is a standard adult draw length."; } recDiv.innerText = advice + " Most compound bows are adjustable in 0.5-inch increments."; }

How to Determine Your Perfect Draw Length

Choosing the correct draw length for your compound bow is the single most important factor in achieving accuracy and comfort. If your draw length is too long, you will struggle with form and likely experience "string slap" on your forearm. If it is too short, you won't be able to reach a consistent anchor point, leading to erratic shots.

The Wingspan Method (The 2.5 Formula)

The most widely accepted method used by professional archery shops to find a starting draw length is the Wingspan Formula. This method relies on the proportional relationship between your arm span and the length of your draw.

1. Stand tall with your back against a wall.
2. Extend your arms out to the sides, parallel to the floor, with your palms facing forward.
3. Have a friend measure from the tip of one middle finger to the tip of the other middle finger. Do not stretch excessively; maintain a natural, relaxed posture.
4. Divide the total measurement (in inches) by 2.5.

Example Calculations

Wingspan	Calculation	Estimated Draw Length
68 Inches	68 / 2.5 = 27.2	27″ or 27.5″
72 Inches	72 / 2.5 = 28.8	29″
75 Inches	75 / 2.5 = 30.0	30″

Fine-Tuning Your Fit

While the calculator provides a highly accurate starting point, personal preference and "anchor points" play a role. Here are a few things to consider:

• The Release Aid: The type of release you use (index finger vs. thumb button) can slightly change how a draw length feels.
• D-Loop Length: Adding a D-loop to your string adds about 0.5 inches to your effective draw length. Many archers choose to drop their bow's mechanical draw length by 0.5 inches to compensate.
• Shoulder Alignment: When at full draw, your front shoulder should be low and relaxed, not bunched up against your chin. If your shoulder is pushed back, your draw length is likely too long.

Signs Your Draw Length Is Wrong

If you have already purchased a bow, look for these red flags:

Too Long: You find yourself leaning your head back to see through the peep sight, or the string is hitting your forearm frequently. You may also feel a "creep" where the bow wants to take off because you can't stay in the valley.

Too Short: You feel cramped, your nose doesn't touch the string (if that is your preferred anchor), and you struggle to keep the bow steady because your muscles are overly contracted.

Expert Tip: Always round to the nearest half-inch. Most modern compound bows feature adjustable cams that allow you to change the draw length without a bow press, making it easy to test small adjustments after using this calculator.