Best Inside Micrometer (2026): 4 Picks for Bore and Engine Work
Inside micrometers for bore, bearing and engine work, compared by range, resolution, accuracy, extension rods, case and warranty.
On this page
Top picks at a glance
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- 1
Best OverallStarrett 124BZ9.6/10View on Amazon - 2
Widest RangeAccusize 3011-50519.6/10View on Amazon - 3
Most Precise Small RangeAccusize EG00-32219.6/10View on Amazon
A cylinder bore needs a check after a rebuild, and a caliper cannot reach the inside wall with the precision the job needs. An inside micrometer spans the bore and reads the internal size, so a worn cylinder or a tight bearing housing shows up before parts go back together. This guide covers the best inside micrometer options, compared by range, resolution, accuracy, rods and case, so the choice fits the bore, the engine and the bench.
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Quick picks
- Best Overall Starrett 124BZ: 2 to 12 in range with 0.001 in graduation, insulated rods, hardened anvils and a one year warranty. Check price on Amazon
- Widest Range Accusize 3011-5051: 2 to 24 in range with extension rods of 0.5, 1, 2, 4, 6 and 8 in and a 0.0001 in resolution. Check price on Amazon
- Most Precise Small Range Accusize EG00-3221: 0.2 to 1.2 in range with 0.00028 in accuracy, a ratchet stop and a locking clamp. Check price on Amazon
Picks for the garage
Accusize Industrial Tools 2-24'' by 0.001''
An inside micrometer set with a 2 to 24 in range, extension rods of 0.5, 1, 2, 4, 6 and 8 in, a 0.0001 in resolution and a caliper gauge for zero setting.
Pros
- 2 to 24 in range, the widest here
- Extension rods of 0.5, 1, 2, 4, 6 and 8 in
- 0.0001 in resolution with 0.001 in increments
- Caliper gauge for zero setting in a fitted case
Cons
- No warranty term is stated
- Accuracy is given as a metric formula, not a plain figure
- Rod diameter of 0.61 in limits smaller bores
- No ratchet stop is stated
Starrett Solid Rod Inside Micrometer Set
A solid rod inside micrometer set with a 2 to 12 in range, 0.001 in graduation, insulated rods, hardened and ground anvils and a padded case.
Pros
- 2 to 12 in range with 0.001 in graduation
- Insulated rods marked with length
- Hardened and ground anvils
- One year warranty on defects in material and workmanship
Cons
- No accuracy figure is stated
- No resolution figure beyond graduation is stated
- No extension rod sizes are stated
- No ratchet stop is stated
Accusize Industrial Tools Inside Micrometer
An inside micrometer with a 0.2 to 1.2 in range, 0.001 in graduation, 0.00028 in accuracy, a ratchet stop and a locking clamp, with a satin chrome finish.
Pros
- 0.00028 in accuracy for small bores
- Ratchet stop for consistent measurement force
- Locking clamp to hold the setting
- Hardened and ground faces with a satin chrome finish
Cons
- Resolution is given as 0.0001 in in the title and 0.001 in in the bullets
- No case is stated
- No warranty term is stated
- Range covers 0.2 to 1.2 in only
Tallew 1 Set Micrometer Set 0-4"
A micrometer set with a 0 to 4 in outside micrometer set and a 6-piece telescoping bore gauge set for 5/16 to 6 in, with a pouch and a case.
Pros
- Bore gauge range of 5/16 to 6 in
- Outside micrometers from 0 to 4 in
- 6-piece telescoping bore gauge set
- Blue fabric pouch and black plastic case included
Cons
- No direct inside micrometer is included
- No accuracy figure is stated
- No resolution figure is stated
- Spec table gives dimensions of 0.39 in on each side
Compared on paper
| Model | Shop Score | Range | Resolution | Accuracy | Case | Warranty |
|---|---|---|---|---|---|---|
| Starrett 124BZ | 9.6/10 | 2-12 in | 0.001 in graduation | Not stated | Padded case | One Year |
| Accusize 3011-5051 | 9.6/10 | 2-24 in | 0.0001 in | Metric formula | Fitted case | Not stated |
| Accusize EG00-3221 | 9.6/10 | 0.2-1.2 in | 0.0001 in | 0.00028 in | Not stated | Not stated |
| Tallew UG-Tallew-5715 | 9.5/10 | 5/16-6 in bore | Not stated | Not stated | Pouch and case | Not stated |
Specifications are manufacturer rated, as published on each listing and collected 2 November 2026. Where a listing contradicts itself, both figures are shown.
How the points were given
Each micrometer is scored on performance, build, value, safety and warranty, with the weights published on the How We Pick page. None states a UL, ETL or CSA listing, so no safety points are given. A warranty is stated for the Starrett pick only.
| Product | Shop Score | Perf. /35 | Build /25 | Value /25 | Safety /10 | Warranty /5 |
|---|---|---|---|---|---|---|
| Accusize 3011-5051 | 9.6 | 30 | 21 | 21 | n/a | 0 |
| Starrett 124BZ | 9.6 | 29 | 22 | 20 | n/a | 0 |
| Accusize EG00-3221 | 9.6 | 28 | 21 | 20 | n/a | 0 |
| Tallew UG-Tallew-5715 | 9.5 | 26 | 20 | 20 | n/a | 0 |
Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score. Safety counts only for powered gear or where the listing states safety features; where it does not apply, the score is taken over the remaining 90 points.
What the listings tell you
The listings here give range for every pick, and resolution for the Accusize picks. The Starrett listing gives a range of 2 to 12 in with 0.001 in graduation, the Accusize 3011 listing gives a range of 2 to 24 in, the Accusize EG00 listing gives a range of 0.2 to 1.2 in, and the Tallew listing gives a bore gauge range of 5/16 to 6 in with outside micrometers from 0 to 4 in. Accuracy is stated for the Accusize EG00 pick at 0.00028 in, and as a metric formula for the Accusize 3011 pick, with no accuracy stated for the Starrett or Tallew picks.
Best inside micrometer: what to check
Range and rods
Range sets the bore size the tool can span. The Starrett pick covers 2 to 12 in, the Accusize 3011 pick covers 2 to 24 in with extension rods of 0.5, 1, 2, 4, 6 and 8 in, and the Accusize EG00 pick covers 0.2 to 1.2 in. The Tallew pick covers a bore gauge range of 5/16 to 6 in, with outside micrometers from 0 to 4 in, so check the bore size in use before choosing a range.
Resolution and accuracy
Resolution and accuracy set how fine the reading can be. The Accusize EG00 listing states a resolution of 0.0001 in in the title and 0.001 in in the bullets, with an accuracy of 0.00028 in, so both resolution figures are shown here. The Accusize 3011 listing states a resolution of 0.0001 in with 0.001 in increments, and an accuracy given as a metric formula. The Starrett listing states 0.001 in graduation, with no accuracy figure stated.
Direct reading or bore gauge
Three picks here are direct inside micrometers, while the Tallew pick is a combo set. The Tallew listing states a 6-piece telescoping bore gauge set with an outside micrometer set, where the bore gauge expands inside a hole, captures the internal size, and transfers that reading to the outside micrometer for checking. That workflow suits cylinder bores, bearing housings and bushings, with no direct inside reading stated for the combo set.
Case and storage
A case keeps rods and gauges in order on the bench. The Starrett pick includes a padded case, the Accusize 3011 pick includes a fitted case with a caliper gauge for zero setting, and the Tallew pick includes a blue fabric pouch for the bore gauge set and a black plastic case with foam support for the outside measuring tools. No case is stated for the Accusize EG00 pick.
Use rated jack stands on solid ground, wear eye protection with power and air tools, keep fuel-burning equipment out of a closed garage, and follow the manual for every tool. Read our Safety Disclaimer.
Garage Fit Check
- Range: the Starrett pick covers 2 to 12 in, the Accusize 3011 pick covers 2 to 24 in, and the Accusize EG00 pick covers 0.2 to 1.2 in, so check bore size before buying.
- Rods: the Accusize 3011 pick includes rods of 0.5, 1, 2, 4, 6 and 8 in, with a caliper gauge for zero setting, so check rod sizes for the bore in use.
- Storage: the Starrett pick includes a padded case, the Accusize 3011 pick includes a fitted case, and the Tallew pick includes a blue fabric pouch and a black plastic case, so check bench space for the case.
- Weight: the Starrett pick weighs 2.16 lb, and the Tallew pick weighs 5.34 lb, so check handling for the set in use.
FAQ: garage tools
What is an inside micrometer?
An inside micrometer measures the internal size of a bore or housing. The picks here state ranges from 0.2 to 1.2 in, 2 to 12 in and 2 to 24 in, with the Tallew pick using a bore gauge and an outside micrometer to check the same kind of size.
How do you read an inside micrometer?
The Accusize EG00 pick states a ratchet stop for consistent measurement force and a locking clamp to hold the setting, and the Starrett pick states quick-reading figures on insulated rods marked with length. Check the maker instructions for the pick in use before measuring.
What accuracy do these inside micrometers state?
The Accusize EG00 listing states an accuracy of 0.00028 in. The Accusize 3011 listing states accuracy as a metric formula, and no accuracy figure is stated for the Starrett or Tallew picks.
What range fits engine work?
The Starrett pick covers 2 to 12 in, the Accusize 3011 pick covers 2 to 24 in, and the Tallew pick covers a bore gauge range of 5/16 to 6 in. Match the range to the bore in use, and check the listing for the range before buying.
Do inside micrometers come with a case?
The Starrett pick includes a padded case, the Accusize 3011 pick includes a fitted case, and the Tallew pick includes a blue fabric pouch and a black plastic case. No case is stated for the Accusize EG00 pick.
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