Taper Calculator — Angle, TPF & Lathe Setup
Calculate taper per foot, included angle, and tailstock offset. Morse, Jarno, B&S, NPT, and custom tapers.
Why This Construction Metric Matters
Why: Taper fit is critical for tool holders, drill chucks, and pipe threads.
How: TPF = (D−d)/L × 12. Offset = TPF × L / 24.
- ●Morse #2 most common.
- ●Tailstock offset for long tapers.
- ●NPT: 3/4" per foot.
📋 Quick Examples — Click to Load
📊 Standard Taper TPF
📊 Taper Type Comparison
📊 Your Results
📊 Standard Angles
Planning estimates only. Verify with a licensed engineer or contractor before construction.
📐 Construction Industry Facts
TPF = (D−d)/L × 12
— ASME B5.10
Tailstock offset = TPF × L / 24
— Lathe setup
Taper per foot (TPF) = (Large D − Small D) / Length × 12. Taper angle = arctan((D−d)/(2L)). Tailstock offset = TPF × Lathe Length / 24. Morse tapers ~0.6"/ft; NPT pipe 0.75"/ft. Critical for tool holders, drill chucks, and pipe threads.
Sources: ASME B5.10, Machinery's Handbook, ASME B1.20.1.
Key Takeaways
- • TPF = (D − d) / L × 12; Angle = arctan((D−d)/(2L)).
- • Tailstock offset = TPF × Length / 24 for lathe taper turning.
- • Morse ~0.6"/ft; NPT = 3/4"/ft; Jarno = 0.6"/ft.
- • Self-holding (Morse) vs self-releasing (1:10) tapers.
Did You Know?
How Does Taper Calculation Work?
TPF from Dimensions
TPF = (Large D − Small D) / Length × 12. Converts diameter change over length to inches per foot.
Taper Angle
Half angle = arctan((D−d)/(2L)). Included angle = 2 × half angle. Used for compound rest setup.
Tailstock Offset
Offset = TPF × Distance between centers / 24. Shifts tailstock to create taper when turning between centers.
Expert Tips
Standard Taper Comparison
| Taper | TPF | Angle | Use |
|---|---|---|---|
| Morse #0 | 0.6246 | 1.49° | Morse |
| Morse #1 | 0.5986 | 1.43° | Morse |
| Morse #2 | 0.5994 | 1.43° | Morse |
| Morse #3 | 0.6024 | 1.44° | Morse |
| Morse #4 | 0.6232 | 1.49° | Morse |
| NPT 1/2" | 0.7500 | 1.79° | NPT |
| NPT 3/4" | 0.7500 | 1.79° | NPT |
| Jarno #4 | 0.6000 | 1.43° | Jarno |
Frequently Asked Questions
What is taper per foot (TPF)?
TPF is the change in diameter per foot of length. Formula: TPF = (Large D − Small D) / Length × 12. Morse tapers are ~0.6"/ft; NPT pipe threads are 0.75"/ft (3/4" per foot).
How is taper angle calculated?
Taper angle (half angle) = arctan((D − d) / (2 × L)) in degrees. Included angle = 2 × taper angle. TPF and angle are related: TPF = 12 × tan(angle) × 2 for full diameter change.
What is tailstock offset for lathe taper turning?
Offset = TPF × Lathe Length / 24. The tailstock is shifted to create the taper when turning between centers. Use compound rest for short tapers (<2"); tailstock for longer tapers.
Morse taper #2 dimensions?
Morse #2: Large D 0.700", Small D 0.572", Length 2.5625", TPF ~0.5994. Most common for drill chucks and lathe centers. Self-holding taper.
NPT taper specification?
NPT (National Pipe Thread) uses 3/4" per foot (0.75" TPF) for all sizes. Included angle ~3.58°. Used for pipe threads and hydraulic fittings. Self-releasing when compared to Morse.
Self-holding vs self-releasing tapers?
Self-holding (Morse, Jarno, B&S) lock by friction. Self-releasing (1:10, 1:20) have steeper angles for easy removal. NPT is tapered for pipe sealing.
Key Statistics
Official Data Sources
⚠️ Disclaimer: This calculator is for educational purposes only. Verify critical dimensions against official standards. Machining requires proper setup and safety.
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