Looking for the most reliable and updated Tap Drill Chart Metric and Standard 2025?
This comprehensive resource explains everything you need to know about tap drill sizes, thread standards, drilling calculations, tool selection, and best practices for creating accurate internal threads in metals, plastics, and composites.
Whether you are a machinist, engineer, CNC programmer, or manufacturing manager, this guide gives you the precise data you need for threading success in 2025 and beyond.
Table of Contents
- What Is a Tap Drill Chart?
- Tap Drill Chart – Metric (2025 Update)
- Tap Drill Chart – Standard (Imperial) 2025
- How to Choose the Right Tap Drill Size
- Tap Drill Size Calculation Formula
- Industry Applications
- MisolGroup – Precision Thread Cutting Tools
- FAQ
- References
What Is a Tap Drill Chart?
A tap drill chart metric and standard is a reference table used to identify the correct drill bit size required before tapping threads. Drilling the proper hole size is crucial for creating strong, accurate internal threads and preventing tool breakage.
In 2025, tap specifications follow international standards such as:
- ISO Metric Thread Standard
- UNF / UNC – Unified National Fine/Coarse
- NPT – National Pipe Thread
- DIN / JIS Industrial Standards
Using the correct tap drill size ensures:
- Optimal thread percentage (60%–75%)
- Reduced machining torque
- Longer tap life
- Accurate fit between mating parts
Tap Drill Chart – Metric (2025 Update)
Below is the updated tap drill chart metric and standard 2025 for commonly used ISO metric sizes:
| Metric Thread (M) | Pitch (mm) | Tap Drill Size (mm) | Thread Percentage (%) |
|---|---|---|---|
| M3 | 0.50 | 2.5 mm | 72% |
| M4 | 0.70 | 3.3 mm | 70% |
| M5 | 0.80 | 4.2 mm | 70% |
| M6 | 1.00 | 5.0 mm | 75% |
| M8 | 1.25 | 6.8 mm | 75% |
| M10 | 1.50 | 8.5 mm | 70% |
| M12 | 1.75 | 10.2 mm | 70% |
| M16 | 2.00 | 14.0 mm | 72% |
| M20 | 2.50 | 17.5 mm | 70% |
These sizes are commonly used for CNC machining, mold manufacturing, automotive, robotics, and industrial assembly.
Tap Drill Chart – Standard (Imperial) 2025
The following table lists the most accurate **Standard UNF/UNC tap drill sizes** used globally in precision engineering:
| Thread Size | Threads per Inch (TPI) | Tap Drill Size | Thread Percentage |
|---|---|---|---|
| #4-40 UNC | 40 | #43 | 70% |
| #6-32 UNC | 32 | #36 | 75% |
| #8-32 UNC | 32 | #29 | 75% |
| #10-24 UNC | 24 | #25 | 70% |
| 1/4-20 UNC | 20 | 13/64″ | 65% |
| 3/8-16 UNC | 16 | 5/16″ | 72% |
| 1/2-13 UNC | 13 | 27/64″ | 72% |
How to Choose the Right Tap Drill Size
1. Identify the Thread Standard
Determine whether you need metric (M) or imperial (UNC/UNF/NPT) threads.
2. Select the Correct Pitch or TPI
Pitch defines the thread spacing—critical for determining the tap drill diameter.
3. Define The Thread Percentage
- 60% – Easy tapping, recommended for stainless steel
- 70% – Standard industrial use
- 80% – Strong engagement but higher torque
4. Consider the Material
- Soft metals (aluminum, brass) → higher thread percentage
- Hard metals (stainless steel, titanium) → lower thread percentage for lower torque
Tap Drill Size Calculation Formula
Metric Thread Formula
Tap Drill Size = Major Diameter – Pitch
Example for M10 × 1.5:
10.0 mm – 1.5 mm = 8.5 mm drill
UN/UNF Imperial Formula
TDS = Major Diameter – (1 / TPI)
Example: 1/4″-20 UNC
0.250″ – (1/20 = 0.050″) = 0.200″ (≈ 13/64″)
Industry Applications of Tap Drill Charts
Modern manufacturing in 2025 relies heavily on accurate tapping operations. A detailed tap drill chart metric and standard helps ensure repeatability across:
- Automotive engine components
- Aerospace structures and brackets
- Robotics and automation equipment
- CNC machined prototypes
- Electronic housings
- Mold making and die manufacturing
Precision threads minimize failure risk and guarantee reliable mechanical fastening.
MisolGroup – Advanced Thread Cutting Solutions
MisolGroup: The Leader in Premium Thread-Cutting Tools
MisolGroup, founded in 2005, is one of China’s most respected manufacturers of high-performance threading tools.
From design and R&D to full-scale production, MisolGroup controls every step to guarantee precision and consistency.
Why Professionals Choose MisolGroup
- Full In-House Production with advanced CNC automation
- Vacuum heat treatment for improved hardness and durability
- Premium HSS materials: M35, DV3, M2
- ISO-certified quality management
- Optimized for difficult materials: stainless steel, cast iron, carbon steel
Featured Products
To learn more, visit MisolGroup Official Website.
Frequently Asked Questions (FAQ)
1. Why do tap drill charts matter?
They ensure correct hole sizes, prevent tap breakage, and improve thread accuracy.
2. Can I use one tap drill size for different materials?
No. Hard materials require lower thread percentage and slightly larger drill sizes.
3. What is the most common mistake when tapping?
Using an undersized drill, which increases torque and causes tool breakage.
4. What is the thread percentage for general machining?
70% is standard for most applications.
References
