Inside micrometer allows you measure internal diameter of an object precisely and accurately.
An inside micrometer is used by professionals to measure the internal dimensions of pipes, holes, registers, and slots with very high accuracy.
There are two types of inside micrometers: analog and digital. The digital model can reach a smallest reading (resolution) down to .00005″.
If you want to measure the external diameter of an object, an outside micrometer would be the right tool. But, when it comes to measuring the internal diameter of a slot or a hole with greater accuracy and precision, an inside micrometer would be the right choice. Although they serve the same purpose, not all inside micrometers are the same.
Using an inside micrometer is pretty similar to the process that you have to follow for outside micrometer. You get a movable thimble and a barrel or main scale. In addition, you get extension rods with inside micrometers that offer different ranges up to 24 inches or even greater.
If you want to buy an inside micrometer that is reliable and serves the purpose with excellence, then we have got some great recommendations for you. We have reviewed some of the best inside micrometers that are trusted by professionals. And at the end, we will include a buying guide to give you a brief idea about what to consider while buying an inside micrometer.
Top 4 Best Inside Micrometers in 2025
| Products | Pictures | Range | Special Feature | Price |
|---|---|---|---|---|
| 1. Starrett 124BZ |  | 5-6 mm | High-grade steel construction that makes it durable | CHECK THE PRICE HERE! |
| 2. iGaging Inside Hole Micrometer |  | 8-10 mm | Allows measurements near the bottom of the blind hole | CHECK THE PRICE HERE! |
| 3. Inside Micrometer Internal Diameter Gauge |  | 5-30 mm | Microlap finish to assure accurate measurement | CHECK THE PRICE HERE! |
| 4. Mitutoyo 345-251-30 IMP-50MX Micrometer |  | 25-50mm | Jaws made from high-grade steel | CHECK THE PRICE HERE! |
1. Starrett 124BZ Inside Solid Rod Micrometer Set [Best Overall]
Our first product is the Starrett inside solid rod micrometer. It is an analog micrometer that offers you a maximum range of 12 inches and comes with 10 measuring rods. The rods can be easily interchanged for different ranges. On the micrometer, you get a rotating thimble with a nut-type lock. The accuracy of this micrometer is ±.00001 inches.
Furthermore, this inside micrometer comes with high-grade hardened anvils that are very sturdy and long-lasting. The extensive range provided by the rods that easily fit and lock in the head of the micrometer makes it ideal for machinists. In the package, you get a plastic box for storage as well.
Pros:
- Very Accurate
- Sturdy
- Quick and easy rod installation
Cons:
- A bit pricey
2. iGaging Inside Hole Micrometer Digital 3-Point Bore Gauge
If you think that using an analog inside a micrometer is a challenging task, then this one can be an excellent choice for you. The iGaging inside hole micrometer is a digital tool that comes with a display unit with a preset button, in/mm button, and hold button in it. Using this micrometer is very easy. It gives you a range of 0.35 – 0.425 inches. The contact points on this micrometer allow you to take measurements near the bottom of the blind spot.
Another very amazing feature of this digital inside micrometer is that it is compatible with tablets and other devices and can be connected to them via a cable. A Carbide ring and a protective case for storage are included in the package.
Pros:
- Easy to use
- Compatible with smart devices
- Accurate results
Cons:
- You don’t get extension rods with it
3. Accusize Industrial Tool Inside Micrometer
This inside micrometer also belongs to the analog type. It gives you a greater measuring range which is starting from 2 inches to 24 inches. That said, it comes with interchangeable measuring rods, each of which is marked with its own measuring range.
For the body material, it is made from top-quality stainless steel, which makes it very durable.
The surface of this micrometer has a carbide coating on its surface which makes it glare-free and resistant to rust. You get a standard caliper gauge with it for zero setting. Inside the package, along with the micrometer, you get a perfect wooden box for storage.
Pros:
- Easy to read
- Sturdy
- Accurate readings
Cons:
- Requires careful handling
4. Mitutoyo 345-251-30 IMP-50MX Micrometer
Finally, we have a digital micrometer from Mitutoyo that offers you exceptional high-quality products that you would expect from a top brand. It offers you a high accuracy of 0.0003 inches. The display unit of this inside micrometer comes with a preset hold and zero buttons. It is powered by the LR44 battery that is included in the package. The jaws of this tool are made from high-grade tool steel. You also get a locking clamp feature that allows you to lock the spindle at any desired position.
You get carbide-tipped measuring faces on it. The satin chrome finish on top of the steel build gives it a premium look and feel. You can get a Mitutoyo micrometer to stand with it. In the package, you get a storage box for it as well.
Pros:
- High Accuracy
- Offers wider range
- Premium finish
Cons:
- Doesn’t show readings in inches
Things To Consider Buying An Inside Micrometer
Due to the mixed reviews and different features, it is very difficult to pick one. To resolve your issue, in this section, we will tell you about some crucial factors that you need to consider while buying an inside micrometer.
1. Type
The first thing that classifies different inside micrometers is their type. You will generally find two types of inside micrometers in the market. The analogs have been used for a long time and offer good accuracy and quality. But if you are looking for an inside micrometer that offers you greater accuracy along with ease of use and quick results, then there is no better option than a digital model. The display unit on it shows very accurate results, and you don’t need to go for any kind of calculation.
2. Range
Another important feature that you need to consider before buying an inside micrometer is the range that it offers. It depends on your requirements. If you want to measure the diameter or dimensions of smaller holes, slots, or registers, then you can choose one with a lesser range. Inside micrometers with a lesser range are comparatively cheaper. If your project requires measuring greater ranges, then you can go for the one that offers a wider range.
3. Build Material
The durability of an inside micrometer depends on its build material. Although this is a tool that you won’t use very often until your tasks require it, you should get the one that lasts a long time, so you don’t have to buy it again. For that purpose, you should go for the one that is made from high-quality stainless steel or high-grade steel that is ideal for such tools. The inside micrometers that are made from such material can resist impact and will not rust or break easily.
4. Finish
If you are choosing an analog inside a micrometer, you will have to take the reading manually. Any glare or light reflection on the graduations can make your task even harder. If you get the micrometer that comes with a satin chrome finish, then this won’t be a problem anymore because such a finish makes the surface glare free. Furthermore, a good finish of a micrometer is a clear indicator that it is a high-quality product.
F.A.Q.
Q: How to check the inside/internal micrometer’s accuracy?
For an inside micrometer, prepare the gauge block holder and half-round jaw and stack the needed length to be measured.
A: Checking the inside micrometer’s accuracy can be done with gauge block holder that has half-round jaw. In this case, like the calibration of other types of micrometer, it requires a set of gauge blocks to check several lengths. Never forget to consider the calibrated gauge blocks so that your inspection is reliable.
Q: How to take care of depth micrometer?
A: Check out these micrometer maintenance points you can do to keep this measuring tool long last.
Conclusion
Getting the right inside micrometer will save you from all the hassle. You can get accurate readings of internal dimensions with unparalleled accuracy and precision. This brings us to the conclusion of the article. We hope that you found this guide very helpful, and you can now select an inside micrometer for yourself that matches your requirements. If you still can’t make a choice, we have got some recommendations for you.
The best overall inside micrometer would be the Starrett 124BZ inside micrometer set, as it comes with a set of rods that offer a very extensive range for measurements. It is made from high-grade steel, which makes it very durable. If you want to buy a digital inside micrometer, then you should go for the iGaging Inside Hole Micrometer as it is very easy to use and comes with a hold reading feature. You can get a greater range of variants of this micrometer as well.