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DefinitionsBIT: abbreviated to a small b (Kbps), unit of measurement in a computer representing a 1 or a 0BYTE: abbreviated to a capital B (KBps), another unit of measurement in a computer, 8 bits are in asingle byte. Other lengths are possible like 16, 32, 64, etc but network communications is based on 8 bitlengths.

Kbps: kilobits per second, or 1000 bits per second

Mbps: Megabits

per second or 1,000,000 bits per second

Is It Bytes or Bits? The small b in Kbps lets us know the unit of measurement is bits. Acapital B would let us know the measurement is in Bytes.

Even though the metric system uses a small k for kilo, the computer industry has chosen to use a capital K in mostcases.

Definition Examples:56Kbps 56 X 1000 bits per second = 56,000 ones and zero's128Kbps 128 X 1000 bits per second = 128,000 ones or zero's460Kbps 460 X 1,000 bits per second = 460,000 ones or zero's1Mbps 1 X 1,000,000 bits per second = 1 million one's or zero's10Mbps 10 X 1,000,000 bits per second = 10 million one's or zero's

Use:

So far so good it would appear that you have enough information to start figuring out howlong it takes to transfer files but you have to remember that these speeds are in BITS not

BYTES. When we look at a file size we look at the number of BYTES not the number ofbits. Using this information we can build the chart below.

Theoretical Maximum Speeds

Common Name Used With Bits per Second Bytes per Second

28.8Kbps Modems 28,800 3,600

56.6Kbps Modems 56,600 7,200

128Kbps ISDN 128,000 16,000

460Kbps Cable Modem 460,000 57,500

1Mbps Home PNA 1.0 1,000,000 125,000

1.6Mbps HomeRF 1,600,000 200,000

10Mbps Ethernet 10,000,000 1,250,000

100Mbps Fast Ethernet 100,000,000 12,500,000

Aprox Theoretical Transfer Times:

CommonName

Used WithTime to Transfer 1Megabyte

Time to transfer 50Megabytes

28.8Kbps Modems 4.5 Min 3.8 Hrs56.6Kbps Modems 2.3 Min 2 Hrs

128Kbps ISDN 1 Min 50 Min

460Kbps Some Cable Modems 17 Sec 14.5 Min

1MbpsHome PNA 1.0, CableModes

8 Sec 6.5 Min

1.6Mbps HomeRF 5 Sec 4 Min

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10Mbps Ethernet 1 Sec 40 Sec

100Mbps Fast Ethernet 1 Sec 4 Sec

Theoretical vs Real times:So many factors go into real transfer times that it is very difficult to wrap blanket numbers

around them. Once you get over ISDN speeds, network latency, protocol overhead, driverefficiency, and all kinds of other technical things get in the way. In general, expect transfer

speeds of 40 to 80% of the maximum speed.

Aprox Real Transfer Times:

Common

NameUsed With

Time to Transfer 1

Megabyte

Time to transfer 50

Megabytes

28.8Kbps Modems 6-12 Min 4.8-9.6 Hrs

56.6Kbps Modems 3-6 Min 2.4-4.8 Hrs

128Kbps ISDN 1-3 Min 1-2.1 hrs

460Kbps Some Cable Modems 22-43 Sec 18-36 Min

1MbpsHomePNA 1.0**, Some Cable

Modes10-20 Sec 8-16 Min

1.6Mbps HomeRF** 6-13 Sec 5-10 Min

10Mbps Ethernet, HomePNA 2.0** 1-2 Sec 50-100 Sec

100Mbps Fast Ethernet 1 Sec 5-10 Sec*