Copper vs Iridium Spark Plug: Which One Should You Buy?
Copper vs iridium spark plug choice explained through copper examples from the listings reviewed here, with thread, gap, pack size and fit notes compared.
On this page
Top picks at a glance
As an Amazon Associate I earn from qualifying purchases.
- 1
NGK BPMR7A Copper Spark Plug9.6/10View on Amazon - 2
YzusGomumu 799584 Carburetor Kit with Spark Plug and Air9.7/10View on Amazon - 3
Champion RC12YC Copper Plus Small Engine Spark Plug9.5/10View on Amazon
Verdict: For the copper vs iridium spark plug choice, pick a copper example below when the part number and thread match your engine. No iridium listing is scored here, so pick iridium only after matching the same part number, thread and gap on an iridium listing.
A mower that coughs, stalls or refuses to start on a still morning often points the owner toward the plug. The copper vs iridium spark plug question comes down to matching the plug to the engine in front of you, not to chasing a label. This comparison looks at what the copper side offers through the listings reviewed here, and names the fit details to check on any plug, copper or iridium, before it goes into an engine.
AcreMowerLab earns a commission when you shop through links here. It never changes your price. Affiliate disclosure.
NGK BPMR7A Copper Spark Plug, 2 Pack
A copper spark plug in a 2 pack, with a 14mm thread, a 0.03 inch gap and a 20k-30k mileage figure in the title, plus trivalent metal plating for corrosion resistance.
Read the full review
The NGK example is a copper spark plug with part number BPMR7A, a 14mm thread and a 0.03 inch gap, sold as a 2 pack with an item weight of 2.4 ounces. The title carries a 20k-30k mileage figure and a list of part numbers it replaces, and the listing says to verify compatibility before purchase. The bullets describe electrode technology across copper, iridium and platinum for the brand range, while the title and spec table put this listing on the copper side with a copper core material.
Pros
- 20k-30k mileage figure stated in the title
- Trivalent metal plating for corrosion resistance and easier removal, per the listing
- Gap size stated at 0.03 inches, so the electrode distance can be checked against the engine manual without guessing
- 2 pack in the box for a spare on the shelf
Cons
- Warranty term is not stated; the listing only says a manufacturer warranty is provided
- Spec table lists vehicle type as Car, Truck, so small-engine fit must be matched by part number
- Top material is listed only as Metal, with no further detail
- No EMI or RFI suppression claim is stated
Champion RC12YC Copper Plus Small Engine Spark Plug
A copper small-engine spark plug with a copper core center electrode, a SAC-9 semi-conductor resistor, a TinTac and ULTRASEAL shell, and a 14mm x 1.25mm thread.
Read the full review
The Champion example is a copper small-engine spark plug with part number 71, a copper core center electrode, a SAC-9 semi-conductor resistor for EMI and RFI suppression, and a TinTac and ULTRASEAL shell. The thread is listed as 14mm x 1.25mm and the item weight as 10.56 ounces. The title lists a box of 6 plugs while the spec table lists 1 Count; the title is trusted over the spec table here, so read the pack as a box of 6.
Pros
- SAC-9 semi-conductor resistor for EMI and RFI suppression
- Copper core center electrode for accurate control of heat range, per the listing
- TinTac and ULTRASEAL shell stated for corrosion protection
- Title lists a box of 6 plugs, giving spares for later changes
Cons
- Title says a box of 6 while the spec table says 1 Count; the title is the safer guide
- Gap size is not stated
- Warranty term is not stated; the listing only says a manufacturer warranty is provided
- Spec table lists vehicle type as Car, Truck while the title names a small engine plug, so fit must be matched by part number
Copper vs iridium spark plug side by side
| Product | Core material | Thread size | Gap | Pack |
|---|---|---|---|---|
| NGK BPMR7A | Copper | 14mm | 0.03 inches | 2 Count |
| Champion RC12YC | Copper | 14mm x 1.25mm | Not stated | Box of 6 in title; 1 Count in spec table |
Figures are manufacturer stated for the example models, collected 28 October 2026.
Copper core: what the examples state
Each example here sits on the copper side. The NGK example lists a copper core material, a 14mm thread and a 0.03 inch gap, with trivalent metal plating that the listing says helps with corrosion resistance and easier removal over time. The Champion example lists a copper core center electrode that the maker says allows accurate control of heat range for longer life, plus a TinTac and ULTRASEAL shell for corrosion protection.
The NGK bullets mention electrode technology across copper, iridium and platinum as a brand range. That wording describes the brand range, not this listing: the title and the spec table put this listing on the copper side, with copper as the core material. Read the brand-range wording as background and the title and spec table as the listing facts.
Thread, gap and fit
Thread size decides physical fit; the gap is a separate setting to check against the engine manual. The NGK example states a 14mm thread and a 0.03 inch gap. The Champion example states a 14mm x 1.25mm thread and leaves the gap unstated, so a buyer matching that plug needs the gap figure from the old plug or the engine manual.
Fit wording needs care on each listing. The NGK title lists part numbers it replaces and the listing says to verify compatibility before purchase, while its spec table lists vehicle type as Car, Truck. The Champion title names a small engine plug while its spec table also lists Car, Truck. Match by part number and thread, and treat the vehicle-type line as the weaker guide on each listing.
For the wider upkeep routine around a riding mower, see our riding mower maintenance guide.
Pack size and weight
Pack size is where the listings differ. The NGK example comes as a 2 pack, with 2 Count in the spec table and an item weight of 2.4 ounces. The Champion title lists a box of 6 plugs while its spec table lists 1 Count, so the title is trusted over the spec table here and the pack reads as a box of 6, with an item weight of 10.56 ounces.
Do not compare the item weights plug for plug: the weights describe different pack counts, and neither listing states a per-plug weight. Read the NGK weight as the weight of its 2 pack listing and the Champion weight as the weight of its box listing, and judge spares by the pack, not by the scale.
The two examples
Acreage and terrain fit
NGK BPMR7A
Champion RC12YC
Matching It to Your Property
- Store spare plugs in a dry shed spot with the rest of the upkeep kit, so a plug change never waits on a trip to town.
- Match the part number on the old plug before buying: the NGK example lists BPMR7A and the Champion example lists 71.
- On rough ground with obstacles, check the plug when the mower already sits in the shed for seasonal upkeep, and keep the old plug for matching.
- Keep the box the plugs came in: the Champion title lists a box of 6, so spares stay together for later changes.
The Acre Score explained
The Acre Score weighs performance (spark, fit and stated mileage figure), build quality (core, shell and plating), value (pack size and what comes in the box), safety (features the listing states) and warranty (a stated term). A factor the listing does not state earns no points, which is why warranty and safety sit empty for each example. How we pick explains the weights.
| Product | Acre Score | Perf. /35 | Build /25 | Value /25 | Safety /10 | Warranty /5 |
|---|---|---|---|---|---|---|
| NGK BPMR7A | 9.6 | 28 | 20 | 20 | n/a | 0 |
| Champion RC12YC | 9.5 | 27 | 19 | 21 | 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.
Keep spare plugs with the rest of the upkeep kit in the shed, and see our mower maintenance pages for the wider seasonal routine.
Read the manual, keep children and pets out of the yard while you work, wear eye and hearing protection and sturdy footwear, and never exceed the slope rating of your machine. Refuel only with the engine off and cool. See CPSC lawn mower safety. Read our Safety Disclaimer.
FAQ: mowing large lots
Which side fits a small engine?
The Champion example is titled as a small engine plug, so it is the clearer small-engine match of the examples here. The NGK example lists part numbers it replaces and says to verify compatibility before purchase, so match those numbers against the old plug. Neither listing here is an iridium plug, so the iridium side has no scored example in this article.
What separates copper from iridium in this comparison?
In this article, only the copper side has listings to score: each example states a copper core, a 14mm thread and a stated pack. The iridium side has no listing here, so this article scores no iridium plug and claims no iridium figure. Match part number, thread and gap on any iridium listing before buying, using the same fit details the copper examples state.
Do the examples share a thread size?
Each example states a 14mm thread. The NGK example states 14mm with no pitch figure, while the Champion example states 14mm x 1.25mm. Thread size alone does not settle fit: match the part number too, and check the gap against the engine manual.
What does the gap figure mean?
The gap is the distance between the plug electrodes, across which the spark jumps at the firing tip. The NGK example states a gap of 0.03 inches. The Champion example leaves the gap unstated, so check the old plug or the engine manual for that figure before buying.
Why does the Champion listing show a different pack count in its spec table?
The title lists a box of 6 plugs while the spec table lists 1 Count. The title is trusted over the spec table, so read the pack as a box of 6. When a listing disagrees with itself, the title and bullets win over the spec table.
