Many stations across the country have electronic left-luggage lockers, which cost around €4 for 24 hours. The majority, inconveniently, are bank-card operated; Amsterdam’s Centraal Station lockers are still coin operated, however.

Classes

The longest train journey in the Netherlands (Maastricht–Groningen) takes about 4½ hours, but the majority of trips are far shorter. Trains have 1st-class sections, but these are often little different from the 2nd-class areas and, given the short journeys

 

Amsterdam Amstel Station

Indeed the map has two levels, (I had not seen that due to working on a small screen,) and the lockers are indeed located on the entry level, pfff had seen that right.
The icon is a suitcase in a safe, on the map as well as in the station itself.

 

 

At Schiphol

Dimensions: 43x34x80cm, small (S): EUR 6

Dimensions: 58x34x80cm, medium (M): EUR 7

Dimensions: 58x50x80cm, medium plus (M+): EUR 8

Dimensions: 90x51x80cm, large (L): EUR 9.50

Dimensions: 120x50x80cm, extra large (XL): EUR 11.50

Baggage can be stored in the designated lockers for a maximum of 168 hours (7 days). You will find baggage lockers throughout the Terminal: at Departure Lounges 1, 2 and 3, the Departure Lounge at Pier D, Arrival Hall 3 and the Baggage Basement Square at level -1 between Arrival Halls 1 and 2.
The storage fee is to be paid by debit or creditcard. Please note that in Europe, credit cards with chips need to be verified by a PIN code. Baggage storage in de Baggage Depot (between Arrival Halls 1 and 2) can be paid for in cash.

 

More info here

 

 

Keukenhof

I have also enquired Keukenhof on leaving luggages at the main entrance, but the lockers are probably not big enough. Here is the specs from their reply: 85 cm high, 40 cm broad, 50 cm deep, hope they fit yours.

 

Amsterdam Centraal

Amsterdam Centraal has luggage lockers in two sizes, €4.90 for the first 24 hours for a small locker (90cm x 45cm x 40cm), €7.60 for a large locker (90cm x 60cm x 40cm).  You can pay by Maestro or by Visa credit card, but not coins.  The locker area is open 24 hours a day.  Maximum deposit 72 hours. 

Rotterdam, Utrecht, Den Haag have similar lockers to Amsterdam, at similar prices, all accepting Maestro or Visa cards.

 

Rotterdam Centraal Station

The left luggage lockers (left) are located near to platform 17, come in two sizes (5-8 Euros for 24 hours) and require a credit or debit card – no cash. The key is a flimsy card a shade bigger than a credit card. The lockers open when it is inserted. Once open it cannot be relocked without payment.

 

Rotterdam Airport

The airport has left luggage lockers located in the transit hall.

 

Maastricht Station

 

 

Eindhoven Airport

Baggage lockers are available near the AKO bookstore.

 

Utrecht Station

Left luggage lockers are near the exit to Jaar Beusplein at the West end of station.

 

Luchthaven Schiphol

You can store your luggage in a luggage locker for up to 168 hours (7 days).

 

 

f times the weight exceeds the standard size.