Japanese vs American Rod Power Ratings, Measured on 2,589 Bass Rods
A casting rod rated to 3/4 oz is usually an M in Japan and an MH in the US. Look closer and American brands disagree with each other by more than they disagree with Japan.
If you have shopped for a Japanese-market rod, you have done this translation in your head: the spec sheet says M, and you wonder whether that is the M you know. The common answer on forums is that JDM rods "run heavy." I put that to the catalog, using 2,589 bass rods from 42 brands with a factory power letter and a printed lure rating.
What the numbers say
- Casting rods do run heavier in Japan, by about one lure-weight step. A rod rated to 3/4 oz is labeled M by 72 of 101 Japanese-market rods and MH by 204 of 305 US-market rods.
- US brands use two different MHs. Eight rate MH casting rods to 1 oz (St. Croix, Daiwa US, Shimano US, ARK, KastKing, 13 Fishing, Powell, Denali). Ten rate them to 3/4 oz (Dobyns, G. Loomis, Lew's, Falcon and six more). That spread is wider than the gap between Japan and the US.
- Spinning rods mostly agree. ML and MH spinning rods carry the same ratings in both markets, and Japanese L spinning rods actually rate lighter.
The 3/4-oz test
The cleanest way to compare labels is to hold the rating still and see what letter each market prints on it. Here are all the bass casting rods in the sample with a maximum lure rating of 20 to 22 g, which is 3/4 oz give or take a rounding.
| Label printed | Japan-market rods | US-market rods |
|---|---|---|
| ML | 8 | 5 |
| M | 72 | 78 |
| MH | 18 | 204 |
| H | 3 | 17 |
| XH | 0 | 1 |
| Total | 101 | 305 |
So a Japanese M and an American MH are, most of the time, the same rating. That is the forum wisdom, and at 3/4 oz it holds. The next section shows why it is only half the picture.
Power letter by power letter
Here is the full spread for casting rods. Each bar covers the middle half of the rods at that letter (25th to 75th percentile), and the dot is the median.
| Power | Japan median | US median | Gap (geo. mean) | n (brands) |
|---|---|---|---|---|
| ML | 15.0 g · 0.53 oz | 12.4 g · 0.44 oz | +32% | 51 (10) · 53 (13) |
| M | 21.0 g · ¾ oz | 17.7 g · ⅝ oz | +20% | 113 (13) · 296 (29) |
| MH | 28.4 g · 1 oz | 28.0 g · 1 oz | +26% | 119 (14) · 600 (29) |
| H | 42.0 g · 1½ oz | 42.5 g · 1½ oz | +20% | 75 (12) · 326 (27) |
Japanese-market rods rate 20 to 32% heavier at ML, M and MH. Two things stand out on the chart. The Japanese M is almost a fixed point: its middle half runs from 21.0 to 21.3 g, which is 3/4 oz, whereas the US M spreads from 1/2 to 3/4 oz. And at MH the two medians agree (both about 1 oz) while the bars do not. 81.5% of Japanese MH casting rods are rated to at least 1 oz, against 53% of US ones, and 44% of US MH rods stop at 3/4 oz. A median sitting on the same number was hiding two populations.
There are two American MHs
Splitting the US MH rods by brand makes the second population visible. Every brand with at least eight MH bass casting rods is plotted at its median rating.
The brands land in two tight clusters: one at 1 oz, one at 3/4 oz. Only iRod sits outside them. The split does not follow price. St. Croix and KastKing share the 1-oz camp, and G. Loomis and Lew's share the 3/4-oz camp. Nor is it confined to MH. The 3/4-oz brands sit one step lower across their whole ladder:
| Brand | M | MH | H |
|---|---|---|---|
| Daiwa (US) | ¾ oz (28) | 1 oz (60) | 1½ oz (49) |
| Shimano (US) | ¾ oz (34) | 1 oz (46) | 1½ oz (23) |
| St. Croix | ⅝ oz (28) | 1 oz (53) | 1.38 oz (35) |
| Dobyns | 0.69 oz (14) | ¾ oz (40) | 1 oz (36) |
| G. Loomis | ⅝ oz (25) | ¾ oz (33) | 1 oz (21) |
| Falcon | ½ oz (11) | ¾ oz (18) | 1 oz (17) |
Read across a row and the pattern is plain. A Dobyns or G. Loomis H is rated like a St. Croix or Shimano US MH. A Dobyns MH is rated like a Daiwa US M. Meanwhile the line ratings agree: MH rods in both camps print a median of 20 lb (310 rods in the 1-oz camp, 240 in the 3/4-oz camp, PE-derived ratings excluded), so the lure rating is the only number on the label that shows which camp a rod is in.
Same company, two markets
Daiwa and Shimano publish separate Japanese and US lineups, which gives a controlled comparison: one company writing spec sheets for two audiences.
| Brand | Power | Japan label | US label |
|---|---|---|---|
| Daiwa | ML | 16.0 g (16) | 17.5 g (12) |
| M | 21.0 g (35) | 21.5 g (28) | |
| MH | 28.0 g (34) | 28.5 g (60) | |
| Shimano | ML | 15.0 g (12) | 12.3 g (6) |
| M | 21.0 g (28) | 21.0 g (34) | |
| MH | 30.0 g (24) | 28.0 g (46) |
Through MH, each company labels its two markets almost identically. Japanese-run lineups use one scale (M near 3/4 oz, MH at 1 oz or above) wherever they are sold. The Japan-versus-US gap in the power-letter table comes mostly from the American brands in the 3/4-oz camp, which make up a large share of the US sample. The one Japanese-market brand that sits with them is Fenwick Japan (MH median 21.0 g, n=8).
Spinning rods mostly agree
| Power | Japan median | US median | Line, JP · US | n (brands) |
|---|---|---|---|---|
| L | 7.1 g · ¼ oz | 10.5 g · ⅜ oz | 6 · 8 lb | 40 (7) · 45 (12) |
| ML | 11.0 g · ⅜ oz | 10.6 g · ⅜ oz | 8 · 10 lb | 53 (12) · 188 (23) |
| M | 16.5 g · 0.58 oz | 17.5 g · ⅝ oz | 13 · 12 lb | 18 (8) · 310 (27) |
| MH | 21.0 g · ¾ oz | 21.3 g · ¾ oz | 14 · 15 lb | 23 (9) · 131 (21) |
For bass spinning rods the letters translate directly at ML, M and MH. The one real difference runs the other way from the forum wisdom: a Japanese L spinning rod is rated to 1/4 oz where a US L is rated to 3/8 oz, and Japanese L and ML rods print lighter line.
The trap in the raw numbers
Before the bass filter, the comparison looked very different. Across all freshwater and inshore lure rods, Japanese-market M spinning rods had a median max lure of 30.0 g against 17.7 g for US ones (n=73 and 752). That is not a labeling difference. The Japanese set is full of seabass, boat-game, squid and tip-run rods, which are lure rods for heavier fisheries, and Japan builds far more of them than the US does. Compare a Japanese seabass M to an American bass M and you will conclude that JDM rods run heavy for reasons that have nothing to do with the letter.
The same caution applies to line ratings. Many Japanese rods print PE braid ratings, and converting those to pound-test produces numbers two to three times the mono and fluoro ratings printed beside them. Every line figure in this post excludes PE-derived ratings.
Using this when you buy
- Read the lure rating, not the letter. The max lure number is the one that separates the camps. The grams-to-ounces converter handles Japanese spec sheets.
- A Japanese casting M is rated like the 3/4-oz MH from Dobyns, G. Loomis, Lew's or Falcon. A Japanese MH is rated like the 1-oz MH from St. Croix or the US Daiwa and Shimano lineups.
- Spinning letters translate, except that a Japanese L is a step lighter.
- Compare across brands by rating. The database filters on lure weight directly, and Rod Power Explained covers what each letter throws in general.
Method
Source. Fishing Rod Database catalog as of October 11, 2026. Every rating is the manufacturer's printed figure. None of these are measurements of the blanks.
Label market is the market a spec sheet was written for. Daiwa and Shimano publish separate Japanese and US lineups, and those are counted separately; every other brand counts in its home market. Brands from other countries are excluded.
Included rods: casting and spinning, 6'6" to 7'6", freshwater or inshore, with a power letter printed by the manufacturer (inferred powers excluded) and a lure-weight rating (test-curve and jig-weight ratings excluded). The bass subset keeps rods whose product or series description names black bass and no other fishery. The filter reads text, not specs, so it cannot shape the lure numbers it is measuring. Result: 564 Japanese-market and 2,025 US-market rods from 42 brands.
Why geometric means. Ratings bunch on a few values: 96.7% of US max-lure ratings sit within 0.6 g of a 1/8-oz step, and Japanese brands favor whole grams. Medians therefore jump from step to step, so the gap column compares geometric means, and the MH comparison uses the share of rods at or above 1 oz.
Robustness. The ML, M and MH casting gaps hold when any single brand is removed. The H gap does not survive removing Daiwa, whose Japanese H lineup includes big-bait rods, so this post makes no claim about H. XH is omitted: US brand medians range from 32 g to 283 g, which is several different rod classes sharing one letter. Daiwa and Shimano make up close to half of the Japanese sample.
Data: summary-by-power.csv (percentiles, geometric means and line ratings by power and market, for the bass set, the full freshwater/inshore set and the Daiwa/Shimano pairs) and brand-ladders.csv (median max lure per brand and power, casting). Free to reuse with a link back to this page. Corrections go through the contact form.
FAQ
Is a Japanese M the same as an American MH?
For bass casting rods, often yes. Of 101 Japanese-market casting rods rated to a 3/4-oz maximum, 72 are labeled M. Of 305 US-market rods rated to 3/4 oz, 204 are labeled MH. But US brands are split: about half rate their MH casting rods to 1 oz, which matches a typical Japanese MH.
What lure weight does a medium-heavy casting rod throw?
It depends on the brand. Among 600 US-market MH bass casting rods, 53% are rated to at least 1 oz and 44% top out at 3/4 oz. Among 119 Japanese-market MH casting rods, 81.5% are rated to 1 oz or more.
Do Japanese spinning rods run heavier than American ones?
Not for bass rods. Median maximum lure ratings match at ML (11.0 g vs 10.6 g) and MH (21.0 g vs 21.3 g). Japanese L spinning rods rate lighter: a median of 1/4 oz against 3/8 oz for US-market L rods, with lighter line ratings at L and ML.
Why do brands rate the same power letter differently?
Power letters are not defined by any industry standard, so each brand sets its own scale. In this sample, US brands fall into two groups at MH: one rates MH casting rods to 1 oz and the other to 3/4 oz, while both print the same 20 lb median line rating.