Flats on First

Starting at $3,427

21 Charles St

Cambridge, MA 02141 East Cambridge Neighborhood
Studio-3 Beds
1-2 Baths
439+ Sq Ft

About Flats on First

Flats on First embodies the best of boutique living, combining the luxuries of a modern apartment community with the comforts of a close-knit neighborhood. Come home to a place of sophistication and serenity in East Cambridge.

Listing Provided By

Pricing and Floor Plans

The total monthly price shown includes only the required fees. Additional fees may still apply to your rent. Use the rental calculator to estimate all potential associated costs.

Studio

S1

$3,427-$4,464 total monthly price

Studio, 1 Bath, 439 Sq Ft

https://imagescdn.homes.com/i2/5pZEcq-cXfc0Eb2QrvjkqDqRuaCCYPz3cLPZBMyA0Ls/116/flats-on-first-cambridge-ma-4.jpg?p=1
S1 Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
316B $3,427 440 Dec 5

1 Bedroom

A1

$3,600-$4,913 total monthly price

1 Bed, 1 Bath, 699 Sq Ft

https://imagescdn.homes.com/i2/VSAoMxWfzQqGnMAb0yFo_U72GU_--M3YktBAYMysTnM/116/flats-on-first-cambridge-ma.jpg?p=1
A1 Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
303C $3,600 699 Now

A7H

$3,645-$4,933 total monthly price

1 Bed, 1 Bath, 767 Sq Ft

https://imagescdn.homes.com/i2/ASWxLfvoUgbEDQk0dZ-LDl9Vt-wKAjhFZQXAlf2NXNI/116/flats-on-first-cambridge-ma-2.jpg?p=1
A7H Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
420B $3,645 767 Now

A4H

$4,078-$5,059 total monthly price

1 Bed, 1 Bath, 896 Sq Ft

https://imagescdn.homes.com/i2/FkKL2C3Mhd8dDi6fcS0a944Q8tSx8yVNNKyxfKtdRgQ/116/flats-on-first-cambridge-ma-5.jpg?p=1
A4H Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
102C $4,078 896 Dec 14

A9

$4,603-$6,039 total monthly price

1 Bed, 1 Bath, 914 Sq Ft

https://imagescdn.homes.com/i2/eIF8Z8iap6E_s1IQAPQ57Db2OfDzTrmvLApIPtB7I1M/116/flats-on-first-cambridge-ma-3.jpg?p=1
A9 Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
213B $4,603 914 Nov 10

2 Bedrooms

B8

2 Beds, 2 Baths, 1,221 Sq Ft

https://imagescdn.homes.com/i2/Cg4CL8mGIouMPSMk_iEWMXDIaWITJpiggFLzzziIZUc/116/flats-on-first-cambridge-ma-6.jpg?p=1
B8 Floor Plan
1 Available Unit
Unit Price Sq Ft Availability
514B -- 1,221 Jan 10, 2026

Fees and Policies

The fees below are based on community-supplied data and may exclude additional fees and utilities. Use the Rent Estimate Calculator to determine your monthly and one-time costs based on your requirements.

Utilities And Essentials

Monthly Electric/Gas Fee
You may be required to obtain applicable utilities independently
Personal Liability Insurance
Obtain independent policy or use recommended insurer
Monthly Sewer Fee
Monthly Water Fee
Monthly Water Fee
Monthly Water Fee
Monthly Electric/Gas Fee
Varies
Personal Liability Insurance
Varies
Monthly Sewer Fee
Varies
Monthly Water Fee
Varies

One-Time Basics

Due at Move In
Security Deposit
Or up to 1 months rent based on application screening results
Due at Move In
Security Deposit
$500

Parking

Garage Rental
Garage Rent
Garage Rental
$175 / mo

Pets

Pet Rent
$60 per cat. $85 per dog. 2 pet maximum.
Pet Rent
$50 - $170 / mo

Personal Add-Ons

Personal Liability Renters Insurance
Recommended insurer if not submitting independent policy.
Personal Liability Renters Insurance
$18.75 / mo

Situational

Month-to-Month Fee
Month-to-Month Fee
Late Fee
Applied to rent over 30 days past due
NSF Fee
Returned check or rejected electronic payment fee
Key Fob Replacement
Key Fob Replacement
Additional Security Deposit
Up to 1 months rent based on application screening results
Lease Buy Out Fee
Lease Buy Out Fee
Automatic Renters Insurance (If coverage lapses)
Personal liability renters insurance applied if previously obtained coverage lapses.
Court Fee
Legal/Eviction Fee
Legal/Eviction Fee
Legal/Eviction Fee
Move Out Fob Fee
Key fob unreturned/lost at move-out.
Move Out Cleaning Fee
Unit returned unclean at move-out
Move Out Damage Fee
Fee for damages found at move-out
Month-to-Month Fee
$700 / occurance
Late Fee
Varies
NSF Fee
$50 / occurance
Key Fob Replacement
$5 - $50 / occurance
Additional Security Deposit
Varies
Lease Buy Out Fee
Varies
Automatic Renters Insurance (If coverage lapses)
$15 / mo
Court Fee
Varies
Legal/Eviction Fee
Varies
Move Out Fob Fee
$50 / occurance
Move Out Cleaning Fee
Varies
Move Out Damage Fee
Varies

Property Fee Disclaimer: Standard Security Deposit subject to change based on screening results; total security deposit(s) will not exceed any legal maximum. Resident may be responsible for maintaining insurance pursuant to the Lease. Some fees may not apply to apartment homes subject to an affordable program. Resident is responsible for damages that exceed ordinary wear and tear. Some items may be taxed under applicable law. This form does not modify the lease. Additional fees may apply in specific situations as detailed in the application and/or lease agreement, which can be requested prior to the application process. All fees are subject to the terms of the application and/or lease. Residents may be responsible for activating and maintaining utility services, including but not limited to electricity, water, gas, and internet, as specified in the lease agreement.

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