Driving Calculations & Formulas for Sweden's Theory Test (Körkort)

Reaction distance is how far you travel from the moment you see a hazard until you begin braking. The theory test usually assumes a reaction time of about 1 second for an alert driver, although it can easily rise to 1.5–2 seconds if you are tired, distracted, or driving in the dark.

Examples

• 50 km/h → (50 ÷ 10) × 3 = 15 m
• 90 km/h → (90 ÷ 10) × 3 = 27 m
• 110 km/h → (110 ÷ 10) × 3 = 33 m

Braking distance is the distance from the instant you press the brake until the car stops. It depends heavily on speed, tyres, brakes, road surface, and weather. For the theory test, you can use a simple rule-of-thumb that's surprisingly accurate on dry asphalt.

Examples (dry road)

• 70 km/h → (7² × 0.4) = 19.6 m (≈ 20 m)
• 90 km/h → (9² × 0.4) = 32.4 m (≈ 32 m)
• 110 km/h → (11² × 0.4) = 48.4 m (≈ 48 m)

Multipliers often used in theory questions: wet road ×2, snow/ice ×4–10. Winter tyres help, but physics still wins—low grip means long braking.

Stopping distance combines the two parts above. First you roll during the reaction time, then you brake to a standstill. The total is what really matters when you judge gaps, follow distances, and safe speeds.

Example at 90 km/h (dry road)

• Reaction ≈ 27 m
• Braking ≈ 32 m
• Total ≈ 59 m

In normal conditions, keep at least **two seconds** behind the vehicle ahead. In darkness, rain, or heavy traffic, increase to **three or four seconds**. The "seconds" method works at any speed and is easy to judge: pick a roadside marker, count "one-one-thousand, two-one-thousand"—if you pass the marker before you finish counting, you're too close.

Examples (2 seconds)

• 50 km/h → (50 ÷ 3.6) × 2 ≈ 28 m
• 90 km/h → (90 ÷ 3.6) × 2 ≈ 50 m
• 110 km/h → (110 ÷ 3.6) × 2 ≈ 61 m

Sweden has strict rules around alcohol and driving. Even low levels slow reaction times and impair judgement—bad news for stopping distances. For the theory test you should know the legal thresholds:

Kinetic energy grows with the square of speed. That's why a crash at 100 km/h is far more serious than one at 70 km/h, even if the difference "only" seems like 30 km/h. For stopping, this shows up as the four-times longer braking distance when speed doubles.

Licence categories affect what you can legally tow. The numbers below are the **typical exam facts** you'll be asked to recognise. Always check your registration papers for the exact permitted weights for your specific vehicle and trailer.

Sweden's weather can stretch stopping distances dramatically. The theory test expects you to know how conditions change braking and following distances—even if the formulas stay the same.

• Wet asphalt: plan roughly double braking distance.
• Snow or ice: 4–10× longer. Even ABS can't create grip on polished ice.
• Winter tyres (1 Dec–31 Mar when required): better in cold, but not magic—keep speeds low.
• Studded tyres: improve grip on ice; follow local restrictions and environmental rules.

Do I need to memorise exact decimals? No. Use the rules of thumb here. The theory test focuses on understanding and safe choices, not scientific precision.

What if my reaction time is longer than 1 s? Increase reaction distance proportionally. For example, at 90 km/h with 2 s reaction time you travel about 50 m before braking starts.

Can I rely on ABS to shorten braking? ABS helps you steer while braking, but it does not bend physics. On ice, even ABS can't create grip that isn't there—drop your speed early.

If you can recall those five lines in the exam, you'll handle almost every calculation they throw at you. Combine them with defensive driving—slow early, watch the conditions, and leave generous space—and you'll be both a safer driver and a confident theory-test candidate.

Note: This page summarises common rule-of-thumb values used in Swedish theory training. Always follow current Swedish law and your vehicle's registration data.