Mini, C7, C9 or festoon: choosing the bulb format first
Format decides the look before brand or colour does. Published spacing, draw per bulb, and the job each one is genuinely built for.
By Sawyer V. · Published
Almost every lighting decision people agonise over — warm or cool, this brand or that one — sits downstream of a decision they made without noticing: which bulb format they were buying. Format sets the spacing, the spacing sets the look, and nothing you choose afterwards changes it.
There are four formats that matter on a house, they are easy to tell apart, and the published figures separate them cleanly. Pick the format first and the rest of the category gets much smaller.
Wreath & Watt earns a commission on qualifying purchases made through the Amazon links on this page. It costs you nothing and it does not change the order of the picks — here is exactly how we are funded.
The four formats, side by side
| Format | Typical spacing | Draw per bulb | Reads as |
|---|---|---|---|
| LED mini | 4 in | About 0.05 W | A continuous line of glow |
| C7 | 12 in typical | 5 W incandescent | Defined points, smaller lamp |
| C9 | 12 in | 7 W incandescent, about 1 W LED | Defined points, seen from the street |
| Festoon / G-series | 19.7 in | Not published per bulb | Cafe string, overhead |
Draw per bulb for mini strings is the 5 W per 100-count LED string divided by 100 — our arithmetic. C7 and C9 figures are the standard published lamp ratings; the tag on your own set governs.
Source: Watts = volts x amps at 120 V. The 80 percent ceiling is the standard continuous-load convention for a load running three hours or more. Per-string and per-bulb wattages are the published ratings for those bulb types; the tag on your own set governs.
The arithmetic
- LED mini: 100 bulbs at 4 in spacing = 400 in = 33 ft lighted length
- C9: 25 bulbs at 12 in spacing = 300 in = 25 ft lighted length
- Festoon: 20 bulbs over 32.8 ft = 393.6 in / 20 = 19.7 in spacing
- Same 25 ft of roofline: 25 C9 bulbs, or about 75 mini bulbs
Covering identical distance takes three times the bulb count in mini as in C9 — which is why they read as completely different lighting.
What each format is actually for
C9 is roofline lighting. Twelve-inch spacing produces evenly punctuated points of light that hold their shape from the street, which is the distance a roofline is looked at from. The Wintergreen C9 publishes 25 bulbs over 25 feet on an 18 AWG commercial stringer with drained sockets — the reference specification for this format, and the reason it leads our C9 comparison.
C7 is the same idea one size down. A smaller lamp on the same kind of stringer, drawing about 5 W per incandescent bulb against 7 W for C9. It suits porch rails, door surrounds and anywhere the viewing distance is shorter. It is also the format where clip fitment matters most, because a clip that holds C9 does not automatically hold C7 — the fitment table is on our light clip page.
Mini is for wrapping, not outlining. At 4-inch spacing a 100-count string gives 33 feet of continuous glow, which is exactly what a trunk, a column or a shrub wants and exactly what a roofline does not. The wrapping arithmetic is on wrapping trees and columns.
Festoon is overhead lighting that stays up. The Twinkly Festoon spaces 20 bulbs over 32.8 feet, which computes to 19.7 inches — the widest spacing here and the reason it reads as a cafe string rather than a Christmas set. It is patio hardware that happens to work in December, and the run-length arithmetic is on patio string lights.
The two specialty formats
Icicle and net sets are not really bulb formats at all — they are mini strings arranged in a fixed geometry, sold for a placement rather than a look. An icicle set with 60 drops over 32.8 feet is eave-line hardware and nothing else; a net is hedge hardware. Both are covered on icicle lights and net lights.
The point worth taking from them here is that buying a geometry commits you to a placement. A mini string can become anything; an icicle set can only ever be an eave.
Format changes the load more than colour does
The formats do not draw the same power for the same visual result, and on a large display that decides how many circuits you need.
The arithmetic
- 100 ft of roofline in C9 incandescent: 100 bulbs at 7 W = 700 W
- 100 ft of roofline in C9 LED: 100 bulbs at about 1 W = 100 W
- 100 ft wrapped in LED mini: about 300 bulbs at 0.05 W = 15 W
- 15 A continuous budget = 1,440 W
The same 100 ft costs 700 W in C9 incandescent and 15 W in LED mini. Format and bulb technology together, not colour, decide the circuit.
The incandescent mini string is the outlier worth naming: 100 bulbs over just 20 feet at about 40 W per string, which is roughly eight times the LED equivalent for a shorter lighted length. It exists for people who specifically want the old warm glow, and the full costing is on LED vs incandescent and what lights cost to run.
Choosing, in one pass
- Roofline seen from the street — C9.
- Porch rail, door surround, shorter viewing distance — C7.
- Trunks, columns, shrubs, railings — LED mini.
- Overhead across a porch or patio, all year — festoon.
- An eave line you want to read as icicles — an icicle set.
- A hedge or a long bush run — a net.
Once the format is settled, the count is arithmetic: the lights calculator converts your measured lengths into strings at the spacing you have chosen.
Our picks for this
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 | No imageWintergreen Lighting C9 OptiCore LED, 25 bulbs / 25 ft, warm white18 AWG SPT-1 stringer, 12 in spacing | Rooflines you want to look the same in year five | 8.3/ 10 | Check price #ad · Disclosure |
| 2 | No imageNorthlight LED mini lights, 100 count, 33 ft, green wire100 LEDs, 4 in spacing, 33 ft lighted length | Trees, shrubs and wrapping — the workhorse string | 6.3/ 10 | Check price #ad · Disclosure |
| 3 | No imageTwinkly Festoon, 20 AWW bulbs, 32.8 ft20 tunable-white bulbs over 32.8 ft | Patios and pergolas that stay lit past Christmas | 7.8/ 10 | Check price #ad · Disclosure |
| 4 | No imageIcicle lights, 300 LED over 32.8 ft, 60 drops60 drops over 32.8 ft — one drop every 6.6 in | A full eave line of icicles | 7.0/ 10 | Check price #ad · Disclosure |
| 5 | No imageIncandescent mini lights, 100 count, 20 ft, green wire, UL listed120 V incandescent — roughly 40 W per 100-count stringSkip this | People who genuinely want the old warm glow | 5.3/ 10 | Check price #ad · Disclosure |
Scores are our own weighting of published manufacturer specifications, explained in full on how we research. They are not test results. We have not tested these products.
The picks, in detail
#1 — Rooflines you want to look the same in year five
Wintergreen Lighting C9 OptiCore LED, 25 bulbs / 25 ft, warm white
18 AWG SPT-1 stringer, 12 in spacing
8.3
/ 10
The C9 set built like an installer's stock: heavy stringer, replaceable bulbs, drained sockets. Buy it once for the roofline you re-hang every year.
Published specifications
- Bulb
- C9 OptiCore LED, faceted, replaceable
- Stringer
- 18 AWG SPT-1 commercial wire, green
- Spacing
- 12 in — 25 bulbs over 25 ft
- Socket drainage
- Weep holes for wet-weather use
- Rated wattage per string
- Not published by the manufacturer
Our scoring
- Build
- 9 / 10
- Weather tolerance
- 9 / 10
- Serviceability
- 9 / 10
- Published specs
- 6 / 10
Good
- Commercial 18 AWG stringer instead of the 22 AWG most retail sets use
- Bulbs unscrew individually, so one dead bulb is a bulb, not a string
- Weep-holed sockets are the detail that decides whether a set survives an ice storm
Watch out
- Costs meaningfully more per foot than a big-box set
- Wattage per string is not published, so you cannot pre-compute load from the listing alone
Specs from the Wintergreen Lighting Amazon listing (ASIN B0776ZCHFX), retrieved 2026-09-04.
#2 — Trees, shrubs and wrapping — the workhorse string
Northlight LED mini lights, 100 count, 33 ft, green wire
100 LEDs, 4 in spacing, 33 ft lighted length
6.3
/ 10
The default mini string. Buy the count you need for the tree, not the count that was on sale.
Published specifications
- Count
- 100 LED mini bulbs
- Spacing
- 4 in
- Lighted length
- 33 ft
- Wire
- Green
- Rated wattage per string
- Not published by the manufacturer
Our scoring
- Build
- 7 / 10
- Weather tolerance
- 7 / 10
- Serviceability
- 5 / 10
- Published specs
- 6 / 10
Good
- 4-inch spacing over 33 feet is the density most tree-wrapping guidance assumes
- Green wire disappears into evergreen far better than white
- LED draw means you can run many strings on one circuit — see our amp guide
Watch out
- Wattage is not printed on the listing, so you have to read the tag on the string itself
Specs from the Amazon listing (ASIN B073WJBKPX), retrieved 2026-09-04.
#3 — Patios and pergolas that stay lit past Christmas
Twinkly Festoon, 20 AWW bulbs, 32.8 ft
20 tunable-white bulbs over 32.8 ft
7.8
/ 10
The one set here that has a job in July. Buy it as patio lighting that also does December.
Published specifications
- Bulbs
- 20 AWW (warm to cool white)
- Length
- 32.8 ft
- Cable
- Black
- Use
- Indoor and outdoor
Our scoring
- Published specs
- 8 / 10
- Weather tolerance
- 7 / 10
- Control
- 9 / 10
- Serviceability
- 7 / 10
Good
- Reads as patio lighting in January rather than as leftover Christmas lights
- Tunable white covers both the party setting and the quiet setting
Watch out
- 20 bulbs over 33 feet is sparse if you wanted a dense canopy
Specs from the Twinkly Amazon listing (ASIN B09SHKS6Z2), retrieved 2026-09-04.
#4 — A full eave line of icicles
Icicle lights, 300 LED over 32.8 ft, 60 drops
60 drops over 32.8 ft — one drop every 6.6 in
7.0
/ 10
The icicle set that tells you its drop count. That is the number that decides how it looks, and almost nobody publishes it.
Published specifications
- LEDs
- 300
- Length
- 32.8 ft
- Drops
- 60
- Modes
- 8
- Connectable
- Up to 3 sets end to end
Our scoring
- Published specs
- 9 / 10
- Coverage
- 8 / 10
- Weather tolerance
- 6 / 10
- Serviceability
- 5 / 10
Good
- Drop count and length are both published, so drop spacing is computable before you buy
- Three-set connectability covers about 98 feet from one outlet
Watch out
- Drop lengths vary within the set by design, which reads as untidy on a straight fascia
Specs from the Amazon listing (ASIN B08JQ6G4R8), retrieved 2026-09-04.
#5 — skip this
Incandescent mini lights, 100 count, 20 ft, green wire, UL listed
120 V incandescent — roughly 40 W per 100-count string
5.3
/ 10
Skip this unless the incandescent glow is specifically what you are buying. On a 15 A circuit it costs you three quarters of your strings.
Published specifications
- Count
- 100 incandescent mini bulbs
- Lighted length
- 20 ft
- Voltage
- 120 V, UL certified
- Twinkle
- No twinkle function
- Typical draw
- About 40 W / 0.33 A per string (industry convention for a 100-count mini set)
Our scoring
- Build
- 5 / 10
- Weather tolerance
- 5 / 10
- Serviceability
- 4 / 10
- Published specs
- 7 / 10
Good
- The color rendering LEDs still approximate rather than match
- Cheap enough to treat as consumable
Watch out
- Draws roughly ten times the watts of an equivalent LED string, which caps a 15 A circuit at about 36 strings
- Bulb failures cascade in series sections
Count, length and voltage from the Amazon listing (ASIN B08BJW25WK), retrieved 2026-09-04. The 40 W figure is the standard published draw for a 100-count incandescent mini string and is the same figure used in our load arithmetic.
Questions
›What is the difference between C7 and C9 bulbs?
Size, and therefore draw and viewing distance. C9 is the larger lamp at about 7 W incandescent per bulb; C7 is smaller at about 5 W. Both are typically spaced around 12 inches. C9 holds up better at street distance; C7 suits porch rails and door surrounds.
›Should I use mini lights on my roofline?
Usually not. At 4-inch spacing they read as a continuous glow rather than defined points, which looks vague from the street. Mini strings are wrapping hardware; C9 or C7 is outlining hardware.
›How many mini lights equal a C9 set for the same length?
About three times as many bulbs. A 25 ft run takes 25 C9 bulbs at 12-inch spacing or roughly 75 mini bulbs at 4-inch spacing.
›Can I mix bulb types on one house?
Yes, and most displays that look deliberate do. Use C9 or C7 for outlining and mini for wrapping. Check the load across the whole display rather than per format, since they draw very differently.
Sources
- Wintergreen Lighting C9 OptiCore listing (ASIN B0776ZCHFX) — 25 bulbs over 25 ft, 12 in spacing
- Northlight LED mini listing (ASIN B073WJBKPX) — 100 LEDs, 4 in spacing, 33 ft
- Twinkly Festoon listing (ASIN B09SHKS6Z2) — 20 bulbs over 32.8 ft
- Icicle light listing (ASIN B08JQ6G4R8) — 300 LEDs, 60 drops, 32.8 ft
- Incandescent mini listing (ASIN B08BJW25WK) — 100 bulbs over 20 ft, 120 V UL certified
- Spacing and load arithmetic — Watts = volts x amps at 120 V. The 80 percent ceiling is the standard continuous-load convention for a load running three hours or more. Per-string and per-bulb wattages are the published ratings for those bulb types; the tag on your own set governs.
We have not tested these products. Every figure above comes from a published manufacturer specification or from arithmetic shown on this page, and anything a maker does not publish is printed as unavailable rather than estimated. How that works, and what we will not claim, is set out on how we research.