Carbon Calculator

Estimate the carbon impact of travel decisions using transparent assumptions and documented emission factors. Start with the live calculators below. New tools are released in stages.

Available calculators

New: Madrid ↔ Barcelona — Train vs Flight (flagship comparison)

Hotel Transportation Carbon Calculator

Estimate transport (CO₂e)

Live

Train vs Flight

Compare rail vs air…

Full Trip Carbon

Estimate full trip…

🚆 ✈️ Travel Decision Tool

Answer a few questions to find your best travel option

1 Is there a direct train under 2.5 hours?

2 Do I need to work or want to relax?

3 Am I going to islands or northern Spain?

4 Booking last minute on a budget?

5 Carrying lots of luggage?

🚆 RECOMMENDATION: Take the TRAIN

Based on your answers, the train is your best option!

Why train wins:

Flights are often banned for short distances
Better for work or relaxation
Train stations are easier with luggage

✈️ RECOMMENDATION: FLY without second-guessing

Based on your destination, flying is the clear choice!

Why flying wins:

Islands and northern Spain are better reached by air
Often faster for remote destinations

🔍 RECOMMENDATION: Check BOTH options

For last-minute budget bookings, compare train and flight prices.

What to do:

Check budget airlines for last-minute sales
Compare with train ticket prices
Sometimes flight sales beat last-minute train prices

🤔 RECOMMENDATION: Consider both options

Compare train and flight options based on these factors:

Factors to consider:

Environmental impact (train is greener)
Total door-to-door travel time
Current prices for both options
Personal preference for comfort

📋 Quick Decision Guide

🚆 TRAIN when:

Direct train < 2.5 hours
Need to work/relax
Carrying lots of luggage
Want less stress

✈️ FLY when:

Going to islands/northern Spain
Long distances
Time is critical

🔍 CHECK BOTH when:

Booking last minute on budget
Prices are fluctuating
Flexible on timing