35 vs 20 vs 5 Percent Tint at Night.
Lower Number, Less Light.
What each shade lets through, what changes after dark, and which windows each one can go on in Illinois, front and rear.
35 vs 20 tint comes down to light. 35 percent film lets through 35 percent of the visible light that reaches the glass, 20 percent film 20 and 5 percent film 5. After dark the film takes the same share out of far less light, so 35 leaves you the most to see by and 5 the least. On an Illinois registered car without the medical exemption, 35 is also the only one of the three allowed on the front doors, and only when no window behind the driver is darker.
The law is 625 ILCS 5/12-503; the letters in parentheses are its subsections.
What does the tint percentage measure?
The percentage is VLT, visible light transmission: the share of visible light that gets through. Lower is darker. 35 percent is about a third, 20 percent a fifth and 5 percent a twentieth, so 35 passes seven times the light of 5.
VLT measures visible light only. Infrared rejection is set mostly by the film, so if heat is why you want 5, choose the film first.
What changes after dark?
Only the amount of light outside. At night the road is lit by headlights, streetlights and signs, with dark gaps between, and the film takes the same share out of that. Headlights and lit signs still show through all three. Dim things fade: an unlit curb, a post behind the car, a person in dark clothes.
Which window matters too: you check the side mirrors and blind spots through the front doors, and the rearview mirror looks through the back glass. Those front doors and the windshield are the windows Illinois keeps lightest.
Film quality shows at night too: ceramic stays optically clear, where cheap film can haze. The ceramic window tint page compares S5 and S9.
35 percent at night
35 percent is the lightest of the three and the darkest shade that can go all around. Under (a-5)(2), the front doors may carry nonreflective film of 35 percent or lighter when no window behind the driver’s seat is darker than 35. So 35 on every side window and the back glass is legal on an Illinois registered car with a side mirror on each side, and after dark it keeps the most light of the three. Tint Starz installs 35 in Carbon, S5 and S9.
20 percent at night
Outside the medical exemption, 20 percent never goes on the front doors of an Illinois registered car: the darkest front figure in the statute is 35. The rear has no minimum, but any treated rear window requires a side mirror on each side under (b-5).
With 20 on any rear window, darker than 30, (a-5) leaves the front doors with no film. At night your mirror checks through the front doors stay as they were, and the difference shows over your shoulder and in the rearview mirror. Tint Starz installs 20 in S5 and S9.
5 percent at night
5 percent, limo tint, follows the same rule: on an Illinois registered car outside the medical exemption, it goes on the rear only, and the front doors then take no film. It passes a seventh of the light 35 does, the least of any shade the shop installs, so after dark the side mirrors do more of the work. Tint Starz installs 5 in Carbon, S5 and S9.
The three shades side by side
| Shade | Light through | Films | On the front doors | On the rear, then the front doors take |
|---|---|---|---|---|
| 35 percent | About a third | Carbon, S5, S9 | Yes, when no rear window is darker than 35 | 35 percent or lighter |
| 20 percent | A fifth | S5, S9 | No | No film |
| 5 percent | A twentieth | Carbon, S5, S9 | No | No film |
The two right columns are for Illinois registered cars without the medical exemption. Any treated rear window needs a side mirror on each side.
Can you keep film on the front doors and go darker in back?
Yes, within limits. With 30 percent film on the rear, (a-5)(1) allows 50 percent or lighter on the front doors, and Tint Starz installs 30 in S5. With rear glass tinted at the factory, (a-5)(4) allows 50 or lighter on the front. On an Illinois registered car without the medical exemption, aftermarket rear film darker than 30 means no front film.
What about the windshield?
On an Illinois registered car without the medical exemption, none of the three goes below the top of the windshield. Subsection (a) allows nonreflective film along the top only, no more than 6 inches down, and sets no darkness figure for that strip. Full windshield film is for cars registered in another state or with the medical exemption.
A sunstrip, a band of film across the top of the windshield, starts at $60. On an Illinois registered car without the medical exemption, the law allows it only if it is nonreflective and reaches no more than 6 inches down from the top.
The two exceptions
Under (f)(2), a car properly registered in another state is exempt from the windshield, front side, rear and mirror rules. Under (g), the windshield and front side rules are lifted for a car with distinctive plates or a sticker under Section 3-412(k), driven by its owner or carrying someone who lives at the owner’s address, when that person has a disease that requires shielding from direct sun and a physician licensed in Illinois certifies it every 4 years. The Illinois window tint law page has every rule with its subsection.
See the three shades before you pick
The shade picker on the window tint shades page shows every shade Tint Starz stocks, 70 down to 5, with its films, sedan starting price and Illinois note. It is a simulation on one sedan photo, not a photo of each shade, and it does not show night.
Shade does not change the price: 35 and 5 cost the same in the same film. On a sedan, S5 starts at $330 and S9 at $400. Call with the year, make and model and the shades you are weighing, or send them through the quote form, and the shop calls you back with an exact price within minutes during shop hours.
Every car is tinted in the shop on Oakton Street in Elk Grove Village. From Hoffman Estates Village Hall it is about 19 minutes outside rush hour: see window tint in Hoffman Estates.
What tint percentage is best for night driving?
Of 35, 20 and 5 percent, 35 lets the most light through after dark, about a third. On an Illinois registered car without the medical exemption, it is also the only one of the three allowed on the front doors, and only when no rear window is darker than 35.
Lighter still, Tint Starz stocks 50 percent in S5 and S9 and 70 in S9; both are legal on the front doors unless rear film is darker than 30.
Can you see out of 5 percent tint at night?
Yes, but less than through any other shade Tint Starz installs: headlights and lit signs show, and dim things fade. 5 percent film passes a twentieth of the light, a seventh of what 35 passes. On an Illinois registered car without the medical exemption it goes on the rear only, with a side mirror on each side.
With 5 percent on the rear, the front doors take no film. Cars registered in another state are exempt from both rules.
Can I get 20 percent tint in the back and 35 in the front?
Not on an Illinois registered car without the medical exemption. Rear film darker than 30 percent leaves the front doors with no film. For 35 on the front, every rear window must be 35 or lighter, or left clear. With 30 on the rear, the front doors can take 50 or lighter. Cars registered in another state are exempt.
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