The TSK 25K Kolkata is one of the only races in India at this distance. Not a half marathon. Not a marathon. Twenty-five kilometres through the Maidan, past Victoria Memorial, in the cool of a December morning. The unusual distance is the gift and the trap. Half-marathon plans leave you under-prepared. Marathon plans leave you over-trained. Pacing the Kolkata 25K well means understanding that twenty-five is neither, and asks for its own strategy.
Why 25K is its own animal
Twenty-five kilometres is roughly four kilometres longer than a half marathon and seventeen kilometres shorter than a marathon. The difference matters more than it sounds. Most runners can race a half on raw fitness. Most runners cannot race a 25K without paying for the last four kilometres if they paced it like a half.
The trick is to think of the Kolkata 25K as a long half marathon, not a short marathon. Your fueling, your pacing, and your effort distribution should look more like a 21.1K race plan extended, than a 42.2K plan trimmed.
The Maidan and the Memorial
The course winds through the Maidan, Kolkata's vast central green, and past the Victoria Memorial. The setting is unlike any other Indian race. Wide tree-lined avenues. Colonial-era architecture. A city that wakes up to runners in the soft December light.
The course is mostly flat. The atmosphere is calm. The temperature in December is one of the most forgiving in India. None of this means the race is easy. It means the race is honest. The pace you can sustain is the pace you have trained for.
The pacing strategy in three blocks
I find it useful to think of 25K races in three blocks. The first eight. The middle ten. The last seven.
The first eight: hold back
Your goal in the first eight kilometres is to be insulted by how easy it feels. The first kilometre will be slower than your target average. That is fine. The second through the eighth should sit at goal pace or 2-3 seconds slower.
Banking time in a 25K is a mistake. The last seven kilometres are where the time is made or lost, and banking 30 seconds per kilometre in the first eight costs you 60-90 seconds in the final third. The maths is unforgiving.
The middle ten: settle
The middle ten kilometres are the work. The crowd thins. The first wave of adrenaline has faded. Your watch shows you a steady pace. Your body asks if you can hold it. Your answer is what training is for.
Stay on schedule with nutrition. A gel every 30-40 minutes. Sip at every aid station. Cadence over stride length. Drop your shoulders. Keep your eyes 10-15 metres ahead, not at your feet.
The last seven: cash the cheque
The last seven kilometres are where pacing pays. If you have run the first eighteen by effort, your legs will respond when you ask them to. If you have not, they will refuse.
Pick targets ahead. Reel them in slowly. The Maidan opens up at this stage, with longer sightlines and fewer turns, and the runners who paced honestly arrive here with kick in their stride. The runners who did not arrive here with their hands on their knees.
December weather and December pacing
Kolkata in December is mild. Morning temperatures are some of the most pleasant in the country. The humidity is moderate. The sun comes up gently. None of this means hydration does not matter.
Drink at every aid station. 100-150 ml. Small sips. Cooler weather makes runners drink less than they should. Take your nutrition on a clock schedule, not by feeling. December cold dulls appetite the way humidity dulls thirst.
What to wear
A singlet or breathable short-sleeve top. Light shorts. A cap if it is sunny. Arm sleeves for the first kilometre if it feels cold, which you can roll down and discard at the first aid station. Do not overdress for a December morning that will warm by kilometre five.
For broader principles on running in Indian conditions, our guide on Indian heat and monsoon covers the underlying ideas; even December's mild conditions follow the same logic of breathable fabric, anti-chafe coverage, and hydration on a clock.
Training for a 25K
Most plans available online treat 25K as either a long half or a short marathon. Neither is right. A 25K plan should look like a half marathon plan with extended long runs.
The long run progression
Your peak long run for a 25K should be in the 28-32 kilometre range, not 21 and not 36. Build this progressively over a 12-16 week cycle. Two long runs in the final block should include the last 6-8 kilometres at goal race pace, which simulates the demand of the final block of the race.
The middle session
A weekly tempo or threshold session is the cornerstone of 25K training. The middle ten kilometres of the race are run at threshold-adjacent effort, and you build that capacity through deliberate, repeated practice.
Our structured half marathon training plans are a strong starting point for a 25K runner, extended with longer long runs in the final block. If you want a plan tuned to your weekly schedule, use the STRIDD plan generator. For sanity checks on your pace targets, run our calculators.
Race-week logistics
Travel to Kolkata at least two days before the race. Bib collection is straightforward but can take time if you arrive on Saturday afternoon. The hotels near the Maidan fill up early; book in advance.
Kolkata is a food city. The street food is among India's best. None of it should appear on your plate in the 48 hours before the race. Save the kati roll and the puchka for celebration. Race-week food is familiar food.
A small story
The first 25K I ran, I treated it like a marathon and finished with energy I could not spend. The second 25K I ran, I treated it like a half and crashed at kilometre 22. The third one, I treated it like its own distance, paced the first eight conservatively, ran the middle ten by effort, and arrived at kilometre 18 with legs that responded. The race shape matters as much as the race fitness.
What to do this week
Write your block plan on paper. The first eight, the middle ten, the last seven. Pin it where you will see it. Practise the cadence-over-stride form on your next long run. Run a goal-pace block of 6-8 kilometres at the end of one of your long runs in the next fortnight. Visit the TSK 25K Kolkata event page for registration and logistics. Browse Running Lab for more 25K-specific writing.
Kolkata is a city built for runners who pay attention. The Maidan, the Memorial, the December cool, the unusual distance. Respect the 25K. Pace the blocks. Finish with the city around you and the sun just up over the trees.