Methodology

The unit engine

All calculators share one model. Every amount of data is converted to bits, every duration to seconds, and every rate to bits per second. Results are converted from those canonical values into whatever unit you choose. Full precision is kept throughout; rounding happens only when a number is displayed, according to the precision you pick (Auto, 2, 4 or 6 decimal places on the converters).

value in bits    = value × unit factor
result in unit B = value in bits ÷ factor of B
rate (bit/s)     = data in bits ÷ time in seconds

Decimal and binary prefixes

1 byte (B) = 8 bits (b). Decimal (SI) prefixes are powers of 1,000: kilo (k) = 1,000, mega (M) = 1,000,000, giga (G) = 10⁹, tera (T) = 10¹², peta (P) = 10¹⁵. Binary (IEC) prefixes are powers of 1,024: kibi (Ki) = 1,024, mebi (Mi) = 1,048,576, gibi (Gi) = 1,073,741,824, tebi (Ti) = 1,024⁴, pebi (Pi) = 1,024⁵.

• Network speeds are always decimal: 1 Mbps = 1,000,000 bit/s.
• 1 MB/s = 8 Mbps; 1 GB/s = 8 Gbps = 8,000 Mbps; 1 MiB/s = 8.388608 Mbps.
• Decimal and binary units are never mixed silently: GB and GiB are separate choices in every calculator.

Transfer time, data transferred and throughput

transfer time (s) = size in bits ÷ (rate in bit/s × efficiency)

Efficiency is optional and off by default (efficiency = 1). When you switch on the real-world option in the download time calculator or its upload and file transfer versions, it starts at 90% and can be edited. Example: 1 GB at 100 Mbps = 8,000,000,000 ÷ 100,000,000 = 80 s; 10 GB = 800 s = 13 min 20 s. The file transfer calculator's connection presets use nominal signalling rates (USB 2.0 480 Mbps, USB 3.2 Gen 1 5 Gbps, USB 3.2 Gen 2 10 Gbps, Gigabit Ethernet 1 Gbps, 2.5GBASE-T 2.5 Gbps, 10GBASE-T 10 Gbps, Thunderbolt 3/4 40 Gbps), which real transfers never reach.

data transferred (bits) = rate in bit/s × time in seconds
100 Mbps for 2 hours = 100,000,000 × 7,200 = 720,000,000,000 bits = 90 GB

throughput (bit/s) = data in bits ÷ elapsed seconds
utilisation        = throughput ÷ link speed
2.5 GB in 30 s = 666.7 Mbps = 66.7% of a 1 Gbps link

Volume per month and website bandwidth

Converting an amount per day, week or month into a sustained rate divides by the length of the period. A month is the average Gregorian month, 365.2425 ÷ 12 = 30.436875 days = 2,629,746 seconds:

sustained rate = amount in bits ÷ period in seconds
1 TB per month = 8,000,000,000,000 ÷ 2,629,746 ≈ 3.04 Mbps

The bandwidth calculator applies the same month to website traffic:

monthly transfer = visitors × pages per visit × average page size
average Mbps     = monthly transfer in bits ÷ 2,629,746 s ÷ 1,000,000
peak Mbps        = average Mbps × peak factor

Example: 100,000 visitors × 3 pages × 2 MB = 600 GB a month ≈ 1.83 Mbps on average, ≈ 5.5 Mbps at a peak factor of 3. The peak factor (default 3) is an assumption you can change; real traffic peaks depend on the site.

Per-activity rates

Each activity has a download and an upload rate in Mbps per simultaneous use. The full table, with notes and GB per hour, is in internet speed by activity.

Household speed calculator

In the internet speed calculator, the number of simultaneous uses of each activity is multiplied by its rate. Download and upload are summed separately, optional targets are added, and headroom (30% by default, adjustable) is applied:

needed = Σ (count × Mbps per use) × (1 + headroom)

A "download X GB in Y minutes" target adds X × 8,000 ÷ (Y × 60) Mbps to download; an "upload X GB in Y hours" target adds X × 8,000 ÷ (Y × 3,600) Mbps to upload. The suggested plan is the first of these tiers at or above the download figure: 25, 50, 100, 200, 300, 500, 1000 and 2000 Mbps. Above 2000 Mbps no tier is suggested. Example: the Family of 4 (WFH) preset (2 browsing, one 4K and one 1080p stream, two 1080p calls, one online gamer, 10 idle devices) is 38.6 Mbps down and 7.7 Mbps up at peak, or 50.2 and 10.0 Mbps with 30% headroom.

The latency target comes from the most demanding activity you add: cloud gaming first (under 80 ms, NVIDIA), then online gaming (under 50 ms, our guidance), then calls and live streams (one-way delay under 150 ms, ITU-T G.114).

What can my speed handle

Usable capacity is the plan speed times a usable share, 85% by default, to allow for overhead and other traffic. For each activity, the maximum number at once is the smaller of the download and upload limits:

usable = plan × 0.85
max    = min( floor(usable down ÷ down per use), floor(usable up ÷ up per use) )

Browsing, music and idle devices are left out of this table because they are too small to give a useful answer. Download times use the usable speed. Household presets are checked with the household formula above at 30% headroom.

Speed test checker

Your measured speed is divided by your plan speed and graded against thresholds that depend on how you tested. These are our heuristics, not an industry standard:

A wired result of 850 to 960 Mbps on a plan of 900 Mbps or more is flagged as the likely limit of a gigabit Ethernet port, and ping above 100 ms is flagged. Why about 940 Mbps: a standard 1,500-byte Ethernet packet carries 1,448 bytes of TCP data (after IP and TCP headers with timestamps) but takes 1,538 bytes of time on the wire (adding the Ethernet header, checksum, preamble and inter-frame gap), so the most a 1,000 Mbps link can deliver is 1,000 × 1,448 ÷ 1,538 ≈ 941 Mbps.

Data usage and upload calculators

GB per hour  = (down + up) × 3,600 ÷ 8 ÷ 1,000 = (down + up) × 0.45
GB per month = GB per hour × hours per day × 30.4 days

This is an upper bound: streaming services and call apps use adaptive bitrate and often send less than their recommended speed. The cap comparison defaults to 1,200 GB.

upload needed = (stream bitrate + calls × per-call upload + cameras × 2
                 + devices × 0.05 + backup GB × 8,000 ÷ seconds) × (1 + headroom)

The upload calculator compares the result with plan uploads of 10, 20, 35, 50, 100, 300 and 1000 Mbps and shows upload times assuming 90% of each plan's upload is usable.

What is our estimate

Browsing, music, online-gaming traffic, cloud cameras, idle devices, the upload side of cloud gaming, the download side of live streaming, the 85% usable share, the 90% efficiency option, the default 30% headroom, the peak factor of 3, the speed-checker thresholds and the 50 ms gaming target. These are judgement calls, labelled wherever they appear.

Limitations

Services change their recommendations, and real traffic varies with the title, the screen and the app. The calculators don't measure your connection; for that, use a speed test and compare it with the speed test checker. If you find a figure that is out of date, please tell us.

Sources

All checked 26 September 2026.

• Netflix Help Center: Internet connection speed recommendations
• YouTube Help: System requirements
• Zoom Support: Bandwidth requirements
• NVIDIA GeForce NOW: System requirements
• Twitch Broadcasting Guidelines
• ITU-T Recommendation G.114
• FCC: FCC increases broadband speed benchmark
• NIST: SI prefixes and prefixes for binary multiples