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GSTIN 27ADJPJ5621J1ZF · Reference copy · 11 November 2026
STEEL IMPEX INDIA · ENGINEERING REFERENCE
Flange Hole Marking Calculator | PCD, Chord & Coordinates
Enter the pitch circle diameter and hole count to calculate centre positions. Compare straight chord and arc distance, or check how many holes fit on one specified pitch circle with a minimum edge gap.
Open calculator Common questionsCalculation basis
For n equally spaced centres on pitch circle D, angle = 360/n, straight chord = D sin(π/n), and arc = πD/n. Coordinates use radius D/2. The single-ring spacing calculation requires chord ≥ hole diameter + edge gap.
Worked example: 100 mm PCD and 8 holes gives 45° spacing, 38.2683 mm chord and 39.2699 mm arc distance. The first centre at 0° is X = 50 mm, Y = 0 mm.
Prepare a bulk enquiry for delivery within India
Include the material grade, standard and edition, complete size, quantity, finish, certificates, required date and delivery PIN code. For valves include body/trim, seats, service fluid, temperature, end connection and actuator. For fasteners include thread, pitch, length, property class and coating.
For a village, small town or large city, give the district, nearest transport depot and unloading arrangements. Stock, suitability, freight and delivery are confirmed for each order.
Prepare your material enquiry Delivery checklistCommon questions
What is the chord distance between equally spaced flange holes?
For pitch circle diameter D and n equally spaced holes, the straight centre-to-centre chord is D × sin(π/n). A 100 mm PCD with 8 holes gives 38.2683 mm. The arc distance is different: πD/n.
What do the coordinate axes mean?
The pitch-circle centre is the origin. Positive X points right, positive Y points up, and angles increase counterclockwise from positive X. Check the drawing’s orientation and edge distances before marking.
Is equivalent hole area a physical packing count?
No. Dividing one circle area by another gives an area ratio. Actual packing depends on gaps and boundaries. The separate single-ring tool checks equally spaced holes on one specified pitch circle.
Reference sources and corrections · Toolkit terms. Source scope, units and missing values remain part of every reference. A catalogue listing is not a stock guarantee, approval for substitution or brand affiliation.